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  • 1. Order onlineBuy this publication >>
    Abedini, Fereshteh
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    2D and 3D Halftoning for Appearance Reproduction2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The appearance of an object is determined by its chromatic and geometric qualities in its surrounding environment using four optical parameters: color, gloss, translucency, and surface texture. Reconstructing the appearance of objects is of great importance in many applications, including creative industries, packaging, fine-art reproduction, medical simulation, and prosthesis-making. Printers are reproduction devices capable of replicating objects’ appearance in 2D and 3D forms. With the introduction of new printing technologies, new inks and materials, and demands for innovative applications, creating accurate reproduction of the desired visual appearance has become challenging. Thus, the appearance reproduction workflow requires improvements and adaptations. 

    Accurate color reproduction is a critical quality measure in reproducing the desired appearance in any printing process. However, printers are devices with a limited number of inks that can either print a dot or leave it blank at a specific position on a substrate; hence, to reproduce different colors, optimal placement of the available inks is needed. Halftoning is a technique that deals with this challenge by generating a spatial distribution of the available inks that creates an illusion of the target color when viewed from a sufficiently large distance. Halftoning is a fundamental part of the color reproduction task in any full-color printing pipeline, and it is an effective technique to increase the potential of printing realistic and complex appearances. Although halftoning has been used in 2D printing for many decades, it still requires improvements in reproducing fine details and structures of images. Moreover, the emergence of new technologies in 3D printing introduces a higher degree of freedom and more parameters to the field of appearance reproduction. Therefore, there is a critical need for extensive studies to revisit existing halftoning algorithms and develop novel approaches to produce high quality prints that match the target appearance faithfully. This thesis aims at developing halftoning algorithms to improve appearance reproduction in 2D and 3D printing. 

    Contributions of this thesis in the 2D domain is a dynamic sharpness-enhancing halftoning approach, which adaptively varies the local sharpness of the halftone image based on different textures in the original image for realistic appearance printing. The results show improvements in halftone quality in terms of sharpness, preserving structural similarity, and decreasing color reproduction error. The main contribution of this thesis in 3D printing is extending a high quality 2D halftoning algorithm to the 3D domain. The proposed method is then integrated with a multi-layer printing approach, where ink is deposited at variable depths to improve the reproduction of tones and fine details. Results demonstrate that the proposed method accurately reproduces tones and details of the target appearance. Another contribution of this thesis is studying the effect of halftoning on the perceived appearance of 3D printed surfaces. According to the results, changing the dot placement based on the elevation variation of the underlying geometry can potentially control the perception of the 3D printed appearance. It implies that the choice of halftone may prove helpful in eliminating unwanted artifacts, enhancing the object’s geometric features, and producing a more accurate 3D appearance. The proposed methods in this thesis have been evaluated using different printing techniques.    

    List of papers
    1. 3D Halftoning based on Iterative Method Controlling Dot Placement
    Open this publication in new window or tab >>3D Halftoning based on Iterative Method Controlling Dot Placement
    2020 (English)Conference paper, Oral presentation with published abstract (Refereed)
    Abstract [en]

    Realistic appearance reproduction is of great importance in 3D printing’s applications. Halftoning as a necessary process in printing has a great impact on creating visually pleasant appearance. In this article, we study the aspects of adapting and applying Iterative Method Controlling Dot Placement (IMCDP) to halftone three-dimensional surfaces. Our main goal is to extend the 2D algorithm to a 3D halftoning approach with minor modifications. The results show high-quality reproduction for all gray tones. The 3D halftoning algorithm is not only free of undesirable artifacts, it also produces fully symmetric and wellformed halftone structures even in highlight and shadow regions.

    Keywords
    3D printing, 3D halftoning, Surface reproduction
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-171744 (URN)10.2352/ISSN.2169-4451.2020.36.69 (DOI)
    Conference
    Printing for Fabrication, Online 2020, October 19-21
    Available from: 2020-12-01 Created: 2020-12-01 Last updated: 2023-09-26Bibliographically approved
    2. 3D Surface Structures and 3D Halftoning
    Open this publication in new window or tab >>3D Surface Structures and 3D Halftoning
    2020 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    As 3D printing is becoming increasingly popular, the demand for high quality surface reproduction is also increasing. Like in 2D printing, halftoning plays an important role in the quality of the surface reproduction. Developing advanced 3D halftoning methods for 3D printing and adapting them to the structure of the surface is therefore essential for improving surface reproduction quality. In this paper, an extension of an iterative 2D halftoning method to 3D is used to apply different halftone structures on 3D surfaces. The results show that using different halftones based on the 3D geometrical structure of the surface and/or the viewing angle in combination with the structure of the texture being mapped on the surface can potentially improve the quality of the appearance of 3D surfaces.

    Place, publisher, year, edition, pages
    The Society for Imaging Science and Technology, 2020
    Keywords
    3D halftoning, Hybrid halftoning, 3D surface structures
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-170797 (URN)10.2352/ISSN.2169-4451.2020.36.75 (DOI)
    Conference
    Printing for Fabrication 2020
    Available from: 2020-10-22 Created: 2020-10-22 Last updated: 2024-01-02Bibliographically approved
    3. The Effect of Halftoning on the Appearance of 3D Printed Surfaces
    Open this publication in new window or tab >>The Effect of Halftoning on the Appearance of 3D Printed Surfaces
    2021 (English)Conference paper, Published paper (Refereed)
    Abstract [en]

    Managing the final appearance of 3D surfaces is an interesting and essential topic in 3D printing applications. Knowledge about the parameters which influence the 3D surface reproduction quality enables engineers to achieve the final appearance as accurately as designed. Many studies have been conducted to explore numerous parameters that affect the quality of 3D surface reproduction. This work contributes to verifying the role of halftoning in increasing the 3D surface visual quality and the control over the surface appearance of a 3D printed object. The results show that applying different halftones according to the geometrical characteristics of the 3D surface could emphasize or diminish the perceived 3D geometrical structures of a shape. The experimental results are in line with the simulated outputs reported in previous work. Our findings might introduce a new approach towards having more control over 3D appearance reproduction without changing the material or printer settings.

    Keywords
    3D printing, Halftoning, Surface appearance
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-180696 (URN)
    Conference
    47th Annual Conference of Iarigai
    Available from: 2021-10-29 Created: 2021-10-29 Last updated: 2023-09-26Bibliographically approved
    4. Structure-Aware Halftoning Using the Iterative Method Controlling the Dot Placement
    Open this publication in new window or tab >>Structure-Aware Halftoning Using the Iterative Method Controlling the Dot Placement
    2021 (English)In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 65, no 6Article in journal (Refereed) Published
    Abstract [en]

    Many image reproduction devices, such as printers, are limited to only a few numbers of printing inks. Halftoning, which is the process to convert a continuous-tone image into a binary one, is, therefore, an essential part of printing. An iterative halftoning method, called Iterative Halftoning Method Controlling the Dot Placement (IMCDP), which has already been studied by research scholars, generally results in halftones of good quality. In this paper, we propose a structure-based alternative to this algorithm that improves the halftone image quality in terms of sharpness, structural similarity, and tone preservation. By employing appropriate symmetrical and non-symmetrical Gaussian filters inside the proposed halftoning method, it is possible to adaptively change the degree of sharpening in different parts of the continuous-tone image. This is done by identifying a dominant line in the neighborhood of each pixel in the original image, utilizing the Hough Transform, and aligning the dots along the dominant line. The objective and subjective quality assessments verify that the proposed structure-based method not only results in sharper halftones, giving more three-dimensional impression, but also improves the structural similarity and tone preservation. The adaptive nature of the proposed halftoning method makes it an appropriate algorithm to be further developed to a 3D halftoning method, which could be adapted to different parts of a 3D object by exploiting both the structure of the images being mapped and the 3D geometrical structure of the underlying printed surface.

    Place, publisher, year, edition, pages
    I S & T-SOC IMAGING SCIENCE TECHNOLOGY, 2021
    Keywords
    Halftoning, Structure-Aware Halftoning, Hough Transform, Image Quality Evaluation
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-181613 (URN)10.2352/j.imagingsci.technol.2021.65.6.060404 (DOI)000734009600011 ()
    Note

    Funding: ApPEARS (Appearance Printing European Advanced Research School); European Unions Horizon 2020 programme under the Marie Skodowska-Curie [814158]

    Available from: 2021-12-04 Created: 2021-12-04 Last updated: 2023-09-26Bibliographically approved
    5. Structure-Aware Color Halftoning with Adaptive Sharpness Control
    Open this publication in new window or tab >>Structure-Aware Color Halftoning with Adaptive Sharpness Control
    2022 (English)In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 66, no 6, article id 060404Article in journal (Refereed) Published
    Abstract [en]

    Structure-aware halftoning algorithms aim at improving their non-structure-aware version by preserving high-frequency details, structures, and tones and by employing additional information from the input image content. The recently proposed achromatic structure-aware Iterative Method Controlling the Dot Placement (IMCDP) halftoning algorithm uses the angle of the dominant line in each pixels neighborhood as supplementary information to align halftone structures with the dominant orientation in each region and results in sharper halftones, gives a more three-dimensional impression, and improves the structural similarity and tone preservation. However, this method is developed only for monochrome halftoning, the degree of sharpness enhancement is constant for the entire image, and the algorithm is prohibitively expensive for large images. In this paper, we present a faster and more flexible approach for representing the image structure using a Gabor-based orientation extraction technique which improves the computational performance of the structure-aware IMCDP by an order of magnitude while improving the visual qualities. In addition, we extended the method to color halftoning and studied the impact of orientation information in different color channels on improving sharpness enhancement, preserving structural similarity, and decreasing color reproduction error. Furthermore, we propose a dynamic sharpness enhancement approach, which adaptively varies the local sharpness of the halftone image based on different textures across the image. Our contributions in the present work enable the algorithm to adaptively work on large images with multiple regions and different textures. (C) 2022 Society for Imaging Science and Technology.

    Place, publisher, year, edition, pages
    I S & T-SOC IMAGING SCIENCE TECHNOLOGY, 2022
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-192705 (URN)10.2352/J.ImagingSci.Technol.2022.66.6.060404 (DOI)000939908300011 ()
    Note

    Funding Agencies|ApPEARS (Appearance Printing European Advanced Research School); European Unions Horizon 2020 programme under the Marie Sklodowska-Curie grant [814158]

    Available from: 2023-03-31 Created: 2023-03-31 Last updated: 2023-09-26
    6. Effect of halftones on printing iridescent colors
    Open this publication in new window or tab >>Effect of halftones on printing iridescent colors
    2023 (English)In: IS&T Electronic Imaging: Color Imaging XXVIII: Displaying, Processng, Hardcopy, and Applications, The Society for Imaging Science and Technology, 2023, Vol. 35, p. 1-6Conference paper, Published paper (Refereed)
    Abstract [en]

    The iridescent effect produced by structural color is difficult (if not impossible) to capture and print using traditional CMYK pigments. The so called RGB reflective pigments, nonetheless, generate angle-dependent colors by light interference. A layered surface structure generated by the pigments’ particles on a substrate reflects light waves of different wavelengths at different viewing angles according to the optical principle known as the Bragg Law. In this work, we have studied the influence of different halftone structures on printed images, produced with RGB reflective inks via screen printing. The main goal was to enhance the iridescence of a printed reproduction by studying the performance of different halftone algorithms on a screen printing process. We investigated the influence of different halftone structures in creating different spatial combinations of inks on a print to reproduce the image of an iridescent feathered headdress. We applied first-order, second-order, and structure-aware FM halftones to compare how they influence the reproduction of the material appearance of the object represented in the original image. The results show that the structure-ware halftones improve the representation of the image structures and details. Therefore, it could better convey the 3D surface features that produce iridescence in real feathers.

    Place, publisher, year, edition, pages
    The Society for Imaging Science and Technology, 2023
    National Category
    Media Engineering
    Identifiers
    urn:nbn:se:liu:diva-197992 (URN)
    Conference
    IS&T Electronic Imaging
    Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-09-26
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  • 2.
    Abedini, Fereshteh
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Effect of halftones on printing iridescent colors2023In: IS&T Electronic Imaging: Color Imaging XXVIII: Displaying, Processng, Hardcopy, and Applications, The Society for Imaging Science and Technology, 2023, Vol. 35, p. 1-6Conference paper (Refereed)
    Abstract [en]

    The iridescent effect produced by structural color is difficult (if not impossible) to capture and print using traditional CMYK pigments. The so called RGB reflective pigments, nonetheless, generate angle-dependent colors by light interference. A layered surface structure generated by the pigments’ particles on a substrate reflects light waves of different wavelengths at different viewing angles according to the optical principle known as the Bragg Law. In this work, we have studied the influence of different halftone structures on printed images, produced with RGB reflective inks via screen printing. The main goal was to enhance the iridescence of a printed reproduction by studying the performance of different halftone algorithms on a screen printing process. We investigated the influence of different halftone structures in creating different spatial combinations of inks on a print to reproduce the image of an iridescent feathered headdress. We applied first-order, second-order, and structure-aware FM halftones to compare how they influence the reproduction of the material appearance of the object represented in the original image. The results show that the structure-ware halftones improve the representation of the image structures and details. Therefore, it could better convey the 3D surface features that produce iridescence in real feathers.

  • 3.
    Abedini, Fereshteh
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Structure-Aware Color Halftoning with Adaptive Sharpness Control2022In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 66, no 6, article id 060404Article in journal (Refereed)
    Abstract [en]

    Structure-aware halftoning algorithms aim at improving their non-structure-aware version by preserving high-frequency details, structures, and tones and by employing additional information from the input image content. The recently proposed achromatic structure-aware Iterative Method Controlling the Dot Placement (IMCDP) halftoning algorithm uses the angle of the dominant line in each pixels neighborhood as supplementary information to align halftone structures with the dominant orientation in each region and results in sharper halftones, gives a more three-dimensional impression, and improves the structural similarity and tone preservation. However, this method is developed only for monochrome halftoning, the degree of sharpness enhancement is constant for the entire image, and the algorithm is prohibitively expensive for large images. In this paper, we present a faster and more flexible approach for representing the image structure using a Gabor-based orientation extraction technique which improves the computational performance of the structure-aware IMCDP by an order of magnitude while improving the visual qualities. In addition, we extended the method to color halftoning and studied the impact of orientation information in different color channels on improving sharpness enhancement, preserving structural similarity, and decreasing color reproduction error. Furthermore, we propose a dynamic sharpness enhancement approach, which adaptively varies the local sharpness of the halftone image based on different textures across the image. Our contributions in the present work enable the algorithm to adaptively work on large images with multiple regions and different textures. (C) 2022 Society for Imaging Science and Technology.

  • 4.
    Abedini, Fereshteh
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kitanovski, Vlado
    Norwegian University of Science and Technology, Faculty of Information Technology and Electrical Engineering, Department of Computer Science, Gjøvik, Norway.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Structure-Aware Halftoning Using the Iterative Method Controlling the Dot Placement2021In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 65, no 6Article in journal (Refereed)
    Abstract [en]

    Many image reproduction devices, such as printers, are limited to only a few numbers of printing inks. Halftoning, which is the process to convert a continuous-tone image into a binary one, is, therefore, an essential part of printing. An iterative halftoning method, called Iterative Halftoning Method Controlling the Dot Placement (IMCDP), which has already been studied by research scholars, generally results in halftones of good quality. In this paper, we propose a structure-based alternative to this algorithm that improves the halftone image quality in terms of sharpness, structural similarity, and tone preservation. By employing appropriate symmetrical and non-symmetrical Gaussian filters inside the proposed halftoning method, it is possible to adaptively change the degree of sharpening in different parts of the continuous-tone image. This is done by identifying a dominant line in the neighborhood of each pixel in the original image, utilizing the Hough Transform, and aligning the dots along the dominant line. The objective and subjective quality assessments verify that the proposed structure-based method not only results in sharper halftones, giving more three-dimensional impression, but also improves the structural similarity and tone preservation. The adaptive nature of the proposed halftoning method makes it an appropriate algorithm to be further developed to a 3D halftoning method, which could be adapted to different parts of a 3D object by exploiting both the structure of the images being mapped and the 3D geometrical structure of the underlying printed surface.

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    preview image
  • 5.
    Abedini, Fereshteh
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    3D Halftoning based on Iterative Method Controlling Dot Placement2020Conference paper (Refereed)
    Abstract [en]

    Realistic appearance reproduction is of great importance in 3D printing’s applications. Halftoning as a necessary process in printing has a great impact on creating visually pleasant appearance. In this article, we study the aspects of adapting and applying Iterative Method Controlling Dot Placement (IMCDP) to halftone three-dimensional surfaces. Our main goal is to extend the 2D algorithm to a 3D halftoning approach with minor modifications. The results show high-quality reproduction for all gray tones. The 3D halftoning algorithm is not only free of undesirable artifacts, it also produces fully symmetric and wellformed halftone structures even in highlight and shadow regions.

    Download (png)
    preview image
  • 6.
    Abedini, Fereshteh
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Nyström, Daniel
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    The Effect of Halftoning on the Appearance of 3D Printed Surfaces2021Conference paper (Refereed)
    Abstract [en]

    Managing the final appearance of 3D surfaces is an interesting and essential topic in 3D printing applications. Knowledge about the parameters which influence the 3D surface reproduction quality enables engineers to achieve the final appearance as accurately as designed. Many studies have been conducted to explore numerous parameters that affect the quality of 3D surface reproduction. This work contributes to verifying the role of halftoning in increasing the 3D surface visual quality and the control over the surface appearance of a 3D printed object. The results show that applying different halftones according to the geometrical characteristics of the 3D surface could emphasize or diminish the perceived 3D geometrical structures of a shape. The experimental results are in line with the simulated outputs reported in previous work. Our findings might introduce a new approach towards having more control over 3D appearance reproduction without changing the material or printer settings.

    Download (png)
    preview image
  • 7. Ahmad, Tausif
    et al.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Hybrid Color Halftoning2010Conference paper (Refereed)
  • 8.
    Aigner, Wolfgang
    et al.
    St Polten Univ Appl Sci, Austria.
    Enge, Kajetan
    St Polten Univ Appl Sci, Austria; Univ Mus & Performing Arts Graz, Austria.
    Iber, Michael
    St Polten Univ Appl Sci, Austria.
    Rind, Alexander
    St Polten Univ Appl Sci, Austria.
    Elmqvist, Niklas
    University of Maryland, College Park, United States.
    Hoeldrich, Robert
    Univ Mus & Performing Arts Graz, Austria.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Univ Maryland, DC USA.
    Walker, Bruce N.
    Georgia Inst Technol, GA USA.
    Workshop on Audio-Visual Analytics2022In: PROCEEDINGS OF THE WORKING CONFERENCE ON ADVANCED VISUAL INTERFACES AVI 2022, ASSOC COMPUTING MACHINERY , 2022Conference paper (Refereed)
    Abstract [en]

    In their daily lives, people use more than one sense to perceive and interpret their environment. Likewise, audio-visual interfaces can support human data analysts better than interfaces relying on just one sense. While the research communities of sonification and visualization have both carried out extensive research on the auditory and visual representation of data, comparatively little is known about their systematic and complementary combination for data analysis. After two workshops at Audio Mostly 2021 and IEEE VIS, this 3rd workshop on audio-visual analytics continues building a community of researchers interested in combining visualization and sonification.

  • 9.
    Arvidsson, Filip
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Bertilson, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology.
    Deep Learning for the prediction of RASER-MRI profiles2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Magnetic resonance imaging (MRI) is a critical diagnostic tool in medical practice, enabling non-invasive visualization of anatomy and physiological processes. Nonetheless, MRI has inherent spatial resolution limitations, which may limit its diagnostic capabilities. Recently, a new technology employing Radio-frequency Amplification by Stimulated emission of Radiation (RASER) has emerged to improve MRI resolution. Similar to a laser, RASER-MRI signals spontaneously emerge without the need for a radio frequency pulse(RF), which additionally enhances the safety of the process. However, RASER-MRI images frequently exhibit a significant presence of image artifacts due to the nonlinear behavior between image slices. This master’s thesis aims to determine whether image artifacts can be eliminated using deep artificial neural networks. The neural networks were trained on purely synthetic data, due to the complexity of real RASER experiments. The implementation was split into three phases. The first phase focused on the reconstruction of 1D RASER profiles. The test done during this phase showed that the reconstruction was preferably made with a Convolutional Neural Network (CNN). The CNN does not require knowledge of the total population inversion, and the ideal input was the most volatile RASER spectrum. The second phase was dedicated to reconstructing simulated RASER-MRI images. This phase started with the creation of a random RASER-MRI image generator which was used to generate the training and testing data. The reconstruction was successful and was further enhanced with an image-to-image Unet. The entire deep learning pipeline did not suffice for real data, which sparked the third phase. The third phase focused on simulating more realistic RASER data. The new data improved the result, however, the reconstruction did not suffice. Further research needs to be done into ways to make the simulation more realistic to improve the reconstruction of the real RASER-MRI image. However, this project concludes that simulated RASER-spectra can be reconstructed using deep learning.

    Download full text (pdf)
    fulltext
  • 10.
    Bao, Chunxiong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Yuan, Zhongcheng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Univ Oxford, England.
    Niu, Wenxiao
    Nanjing Univ, Peoples R China.
    Yang, Jie
    Nanjing Tech Univ, Peoples R China; Nanjing Tech Univ, Peoples R China.
    Wang, Zijian
    Nanjing Univ, Peoples R China.
    Yu, Tao
    Nanjing Univ, Peoples R China.
    Wang, Jianpu
    Nanjing Tech Univ, Peoples R China; Nanjing Tech Univ, Peoples R China; Changzhou Univ, Peoples R China; Changzhou Univ, Peoples R China.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Westlake Univ, Peoples R China; Westlake Univ, Peoples R China.
    A multifunctional display based on photo-responsive perovskite light-emitting diodes2024In: NATURE ELECTRONICS, ISSN 2520-1131Article in journal (Refereed)
    Abstract [en]

    Current display screens are typically only used for information display, but can have a range of different sensors integrated into them for functions such as touch control, ambient light sensing and fingerprint sensing. Photo-responsive light-emitting diodes (LEDs), which can display information and respond to light excitation, could be used to develop future ultra-thin and large screen-to-body ratio screens. However, photo-response is difficult to achieve with conventional display technologies. Here, we report a multifunctional display that uses photo-responsive metal halide perovskite LEDs as pixels. The perovskite LED display can be simultaneously used as a touch screen, ambient light sensor and image sensor (including for fingerprint drawing) without integrating any additional sensors. The light-to-electricity conversion efficiency of the pixels also allow the display to act as a photovoltaic device that can charge the equipment. Photo-responsive metal halide perovskite light-emitting diodes can be used to create a multifunctional display that can function as a touch screen, ambient light sensor and image sensor.

  • 11.
    Berkesand, Peter
    Linköping University, University Library.
    Teknisk utvärdering av elektroniska publiceringsplattformar2003Report (Other academic)
    Abstract [sv]

    I samband med universitetets utredning Universitetets informationsförsörjning tillsattes resursgrupper. En av dessa grupper var tekniska gruppen som fick i uppgift att se över vilka publiceringssystem som finns.

    Gruppen har undersökt vilka publiceringsplattformar tillgängliga för elektronisk publicering av vetenskapliga publikationer som kan vara intressanta för E-press. Inom gruppen har diskussioner förts kring de olika plattformarna.

    Vid studiebesök och egna tester framstår för närvarande DiVA som det mest genomarbetade systemet för elektronisk publicering. Vi får ett helt igenom färdigt publiceringssystem som går att använda efter några justeringar för att anpassa det till våra behov.

    Både EPrints och DSpace bör utvärderas mer. I synnerhet DSpace som inte ännu används i Sverige. Eventuellt kommer både DSpace och EPrints att installeras och utvärderas närmare under hösten 2003.

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    Teknisk utvärdering av elektroniska publiceringsplattformar
  • 12.
    Broman, Emma
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Faherty, Jacqueline
    Amer Museum Nat Hist, NY USA.
    Kreidberg, Laura
    Max Planck Inst Astron, Germany.
    Zieba, Sebastian
    Max Planck Inst Astron, Germany.
    Hansen, Charles
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Univ Utah, UT USA.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Bock, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    ExoplanetExplorer: Contextual Visualization of Exoplanet Systems2023In: 2023 IEEE VISUALIZATION AND VISUAL ANALYTICS, VIS, IEEE COMPUTER SOC , 2023, p. 81-85Conference paper (Refereed)
    Abstract [en]

    An exoplanet is a planet outside of our solar system. Researchers study known exoplanets and gather data about them through observations and derived data. Ongoing efforts involve finding planets with an environment that supports life, which likely exists in what is known as the habitable zone around a star. Through a participatory design process, we developed a tool that enables the exploration of exoplanet attribute data and provides contextual visual information in a 3D spatial view that seamlessly presents

  • 13.
    Bruckner, Stefan
    et al.
    Department of Informatics, University of Bergen, Bergen, Norway.
    Isenberg, Tobias
    AVIZ, INRIA, Saclay, France.
    Ropinski, Timo
    Institute of Media Informatics / Visual Computing Research Group, Ulm University, Ulm, Germany.
    Wiebel, Alexander
    Department of Computer Science, Hochschule Worms, 52788 Worms, Germany.
    A Model of Spatial Directness in Interactive Visualization2018In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506Article in journal (Refereed)
    Abstract [en]

    We discuss the concept of directness in the context of spatial interaction with visualization. In particular, we propose a model that allows practitioners to analyze and describe the spatial directness of interaction techniques, ultimately to be able to better understand interaction issues that may affect usability. To reach these goals, we distinguish between different types of directness. Each type of directness depends on a particular mapping between different spaces, for which we consider the data space, the visualization space, the output space, the user space, the manipulation space, and the interaction space. In addition to the introduction of the model itself, we also show how to apply it to several real-world interaction scenarios in visualization, and thus discuss the resulting types of spatial directness, without recommending either more direct or more indirect interaction techniques. In particular, we will demonstrate descriptive and evaluative usage of the proposed model, and also briefly discuss its generative usage.

  • 14.
    Bång, Magnus
    et al.
    Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Ragnemalm, Eva L.Linköping University, Department of Computer and Information Science. Linköping University, The Institute of Technology.
    Persuasive Technology: Design for Health and Safety: 7th International Conference on Persuasive Technology, PERSUASIVE 2012, Linköping, Sweden, June 6-8, 2012. Proceedings2012Conference proceedings (editor) (Refereed)
    Abstract [en]

    This book constitutes the proceedings of the 7th International Conference on Persuasive Technology, PERSUASIVE 2012, held in Linköping, Sweden, in June 2012. The 21 full papers presented together with 5 short papers were carefully reviewed and selected from numerous submissions. In addition three keynote papers are included in this volume. The papers cover the typical fields of persuasive technology, such as health, safety and education.

  • 15.
    Chien, Trinh Van
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering. Sungkyunkwan University, South Korea.
    Dinh, Khanh Quoc
    ungkyunkwan Univ, Sch Elect & Comp Engn, Seoul, South Korea.
    Jeon, Byeungwoo
    Sungkyunkwan Univ, Sch Elect & Comp Engn, Seoul, South Korea.
    Burger, Martin
    University of Munster, Germany.
    Block compressive sensing of image and video with nonlocal Lagrangian multiplier and patch-based sparse representation2017In: Signal processing. Image communication, ISSN 0923-5965, E-ISSN 1879-2677, Vol. 54, p. 93-106Article in journal (Refereed)
    Abstract [en]

    Although block compressive sensing (BCS) makes it tractable to sense large-sized images and video, its recovery performance has yet to be significantly improved because its recovered images or video usually suffer from blurred edges, loss of details, and high-frequency oscillatory artifacts, especially at a low subrate. This paper addresses these problems by designing a modified total variation technique that employs multi-block gradient processing, a denoised Lagrangian multiplier, and patch-based sparse representation. In the case of video, the proposed recovery method is able to exploit both spatial and temporal similarities. Simulation results confirm the improved performance of the proposed method for compressive sensing of images and video in terms of both objective and subjective qualities.

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  • 16.
    Chow, Joyce A
    et al.
    RISE Interactive Institute, Norrköping, Sweden.
    Törnros, Martin E
    Interaktiva Rum Sverige, Gothenburg, Sweden.
    Waltersson, Marie
    Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Richard, Helen
    Region Östergötland, Center for Diagnostics, Clinical pathology.
    Kusoffsky, Madeleine
    RISE Interactive Institute, Norrköping, Sweden.
    Lundström, Claes
    Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Sectra AB, Linköping, Sweden.
    Kurti, Arianit
    RISE Interactive Institute, Norrköping, Sweden.
    A Design Study Investigating Augmented Reality and Photograph Annotation in a Digitalized Grossing Workstation2017In: Journal of Pathology Informatics, ISSN 2229-5089, E-ISSN 2153-3539, Vol. 8, no 31Article in journal (Refereed)
    Abstract [en]

    Context: Within digital pathology, digitalization of the grossing procedure has been relatively underexplored in comparison to digitalization of pathology slides. 

    Aims: Our investigation focuses on the interaction design of an augmented reality gross pathology workstation and refining the interface so that information and visualizations are easily recorded and displayed in a thoughtful view. 

    Settings and Design: The work in this project occurred in two phases: the first phase focused on implementation of an augmented reality grossing workstation prototype while the second phase focused on the implementation of an incremental prototype in parallel with a deeper design study. 

    Subjects and Methods: Our research institute focused on an experimental and “designerly” approach to create a digital gross pathology prototype as opposed to focusing on developing a system for immediate clinical deployment. 

    Statistical Analysis Used: Evaluation has not been limited to user tests and interviews, but rather key insights were uncovered through design methods such as “rapid ethnography” and “conversation with materials”. 

    Results: We developed an augmented reality enhanced digital grossing station prototype to assist pathology technicians in capturing data during examination. The prototype uses a magnetically tracked scalpel to annotate planned cuts and dimensions onto photographs taken of the work surface. This article focuses on the use of qualitative design methods to evaluate and refine the prototype. Our aims were to build on the strengths of the prototype's technology, improve the ergonomics of the digital/physical workstation by considering numerous alternative design directions, and to consider the effects of digitalization on personnel and the pathology diagnostics information flow from a wider perspective. A proposed interface design allows the pathology technician to place images in relation to its orientation, annotate directly on the image, and create linked information. 

    Conclusions: The augmented reality magnetically tracked scalpel reduces tool switching though limitations in today's augmented reality technology fall short of creating an ideal immersive workflow by requiring the use of a monitor. While this technology catches up, we recommend focusing efforts on enabling the easy creation of layered, complex reports, linking, and viewing information across systems. Reflecting upon our results, we argue for digitalization to focus not only on how to record increasing amounts of data but also how these data can be accessed in a more thoughtful way that draws upon the expertise and creativity of pathology professionals using the systems.

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  • 17.
    Christoffersson, Anton
    Linköping University, Department of Electrical Engineering, Information Coding.
    Real-time Depth of Field with Realistic Bokeh: with a Focus on Computer Games2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Depth of field is a naturally occurring effect in lenses describing the distance between theclosest and furthest object that appears in focus. The effect is commonly used in film andphotography to direct a viewers focus, give a scene more complexity, or to improve aes-thetics. In computer graphics, the same effect is possible, but since there are no naturaloccurrences of lenses in the virtual world, other ways are needed to achieve it. There aremany different approaches to simulate depth of field, but not all are suited for real-time usein computer games. In this thesis, multiple methods are explored and compared to achievedepth of field in real-time with a focus on computer games. The aspect of bokeh is alsocrucial when considering depth of field, so during the thesis, a method to simulate a bokeheffect similar to reality is explored. Three different methods based on the same approachwas implemented to research this subject, and their time and memory complexity weremeasured. A questionnaire was performed to measure the quality of the different meth-ods. The result is three similar methods, but with noticeable differences in both quality andperformance. The results give the reader an overview of different methods and directionsfor implementing it on their own, based on which requirements suits them.

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  • 18.
    Eilertsen, Gabriel
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kronander, Joel
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Denes, Gyorgy
    University of Cambridge, England.
    Mantiuk, Rafal K.
    University of Cambridge, England.
    Unger, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    HDR image reconstruction from a single exposure using deep CNNs2017In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, Vol. 36, no 6, article id 178Article in journal (Refereed)
    Abstract [en]

    Camera sensors can only capture a limited range of luminance simultaneously, and in order to create high dynamic range (HDR) images a set of different exposures are typically combined. In this paper we address the problem of predicting information that have been lost in saturated image areas, in order to enable HDR reconstruction from a single exposure. We show that this problem is well-suited for deep learning algorithms, and propose a deep convolutional neural network (CNN) that is specifically designed taking into account the challenges in predicting HDR values. To train the CNN we gather a large dataset of HDR images, which we augment by simulating sensor saturation for a range of cameras. To further boost robustness, we pre-train the CNN on a simulated HDR dataset created from a subset of the MIT Places database. We demonstrate that our approach can reconstruct high-resolution visually convincing HDR results in a wide range of situations, and that it generalizes well to reconstruction of images captured with arbitrary and low-end cameras that use unknown camera response functions and post-processing. Furthermore, we compare to existing methods for HDR expansion, and show high quality results also for image based lighting. Finally, we evaluate the results in a subjective experiment performed on an HDR display. This shows that the reconstructed HDR images are visually convincing, with large improvements as compared to existing methods.

  • 19.
    Eilertsen, Gabriel
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Mantiuk, Rafal
    University of Cambridge.
    Unger, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Real-time noise-aware tone mapping2015In: ACM Transactions on Graphics, ISSN 0730-0301, E-ISSN 1557-7368, ISSN 0730-0301, Vol. 34, no 6, p. 198:1-198:15, article id 198Article in journal (Refereed)
    Abstract [en]

    Real-time high quality video tone mapping is needed for manyapplications, such as digital viewfinders in cameras, displayalgorithms which adapt to ambient light, in-camera processing,rendering engines for video games and video post-processing. We propose a viable solution for these applications by designing a videotone-mapping operator that controls the visibility of the noise,adapts to display and viewing environment, minimizes contrastdistortions, preserves or enhances image details, and can be run inreal-time on an incoming sequence without any preprocessing. To ourknowledge, no existing solution offers all these features. Our novelcontributions are: a fast procedure for computing local display-adaptivetone-curves which minimize contrast distortions, a fast method for detailenhancement free from ringing artifacts, and an integrated videotone-mapping solution combining all the above features.

  • 20.
    Elmquist, Elias
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Bock, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Lundberg, Jonas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    SonAir: the design of a sonification of radar data for air traffic control2023In: Journal on Multimodal User Interfaces, ISSN 1783-7677, E-ISSN 1783-8738, Vol. 17, no 3, p. 137-149Article in journal (Refereed)
    Abstract [en]

    Along with the increase of digitalization and automation, a new kind of working environment is emerging in the field of air traffic control. Instead of situating the control tower at the airport, it is now possible to remotely control the airport at any given location, i.e. in a remote tower center (RTC). However, by controlling the airport remotely, the situational awareness and sense of presence might be compromised. By using directional sound, a higher situational awareness could potentially be achieved while also offloading the visual perception which is heavily used in air traffic control. Suitable use cases for sonification in air traffic control were found through workshops with air traffic controllers. A sonification design named SonAir was developed based on the outcome of the workshops, and was integrated with an RTC simulator for evaluating to what degree SonAir could support air traffic controllers in their work. The results suggest that certain aspects of SonAir could be useful for air traffic controllers. A continuous sonification where the spatial positioning of aircraft were conveyed was experienced to be partially useful, but the intrusiveness of SonAir should be further considered to fit the air traffic controllers’ needs. An earcon that conveyed when an aircraft enters the airspace and from which direction was considered useful to support situational awareness.

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  • 21.
    Elmquist, Elias
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ejdbo, Malin
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Bock, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    OpenSpace Sonification: Complementing Visualization of the Solar System with Sound2021In: Proceedings of the 26th International Conference on Auditory Display (ICAD 2021) / [ed] Areti Andreopoulou, Milena Droumeva, Joseph W. Newbold, Kyla McMullen and Paul Vickers, The International Community for Auditory Display , 2021, p. 135-142Conference paper (Refereed)
    Abstract [en]

    Data visualization software is commonly used to explore outer space in a planetarium environment, where the visuals of the software is typically accompanied with a narrator and supplementary background music. By letting sound take a bigger role in these kinds of presentations, a more informative and immersive experience can be achieved. The aim of the present study was to explore how sonification can be used as a complement to the visualization software OpenSpace to convey information about the Solar System, as well as increasing the perceived immersiveness for the audience in a planetarium environment. This was investigated by implementing a sonification that conveyed planetary properties, such as the size and orbital period of a planet, by mapping this data to sonification parameters. With a user-centered approach, the sonification was designed iteratively and evaluated in both an online and planetarium environment. The results of the evaluations show that the participants found the sonification informative and interesting, which suggest that sonification can be beneficially used as a complement to visualization in a planetarium environment.

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  • 22.
    Elmquist, Elias
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Enge, Kajetan
    St. Pölten University of Applied Sciences, St. Pölten, Austria; University of Music and Performing Arts Graz, Graz, Austria.
    Rind, Alexander
    t. Pölten University of Applied Sciences, St. Pölten, Austria.
    Navarra, Carlo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Höldrich, Robert
    University of Music and Performing Arts Graz, Graz, Austria.
    Iber, Michael
    St. Pölten University of Applied Sciences, St. Pölten, Austria.
    Bock, Alexander
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Aigner, Wolfgang
    St. Pölten University of Applied Sciences, St. Pölten, Austria.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Parallel Chords: an audio-visual analytics design for parallel coordinates2024In: Personal and Ubiquitous Computing, ISSN 1617-4909, E-ISSN 1617-4917Article in journal (Refereed)
    Abstract [en]

    One of the commonly used visualization techniques for multivariate data is the parallel coordinates plot. It provides users with a visual overview of multivariate data and the possibility to interactively explore it. While pattern recognition is a strength of the human visual system, it is also a strength of the auditory system. Inspired by the integration of the visual and auditory perception in everyday life, we introduce an audio-visual analytics design named Parallel Chords combining both visual and auditory displays. Parallel Chords lets users explore multivariate data using both visualization and sonification through the interaction with the axes of a parallel coordinates plot. To illustrate the potential of the design, we present (1) prototypical data patterns where the sonification helps with the identification of correlations, clusters, and outliers, (2) a usage scenario showing the sonification of data from non-adjacent axes, and (3) a controlled experiment on the sensitivity thresholds of participants when distinguishing the strength of correlations. During this controlled experiment, 35 participants used three different display types, the visualization, the sonification, and the combination of these, to identify the strongest out of three correlations. The results show that all three display types enabled the participants to identify the strongest correlation — with visualization resulting in the best sensitivity. The sonification resulted in sensitivities that were independent from the type of displayed correlation, and the combination resulted in increased enjoyability during usage.

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  • 23.
    Enge, Kajetan
    et al.
    St Poelten Univ Appl Sci, Austria; Univ Mus & Performing Arts Graz, Austria.
    Elmquist, Elias
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Caiola, Valentina
    City Univ Hong Kong, Peoples R China.
    Rönnberg, Niklas
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Rind, Alexander
    St Poelten Univ Appl Sci, Austria.
    Iber, Michael
    St Poelten Univ Appl Sci, Austria.
    Lenzi, Sara
    Ikerbasque, Spain; Univ Deusto, Spain.
    Lan, Fangfei
    Univ Utah, UT USA.
    Höldrich, Robert
    Univ Mus & Performing Arts Graz, Austria.
    Aigner, W.
    St Poelten Univ Appl Sci, Austria.
    Open Your Ears and Take a Look: A State‐of‐the‐Art Report on the Integration of Sonification and Visualization2024In: Computer graphics forum (Print), ISSN 0167-7055, E-ISSN 1467-8659, Vol. 43, no 3, article id e15114Article in journal (Refereed)
    Abstract [en]

    The research communities studying visualization and sonification for data display and analysis share exceptionally similar goals, essentially making data of any kind interpretable to humans. One community does so by using visual representations of data, and the other community employs auditory (non-speech) representations of data. While the two communities have a lot in common, they developed mostly in parallel over the course of the last few decades. With this STAR, we discuss a collection of work that bridges the borders of the two communities, hence a collection of work that aims to integrate the two techniques into one form of audiovisual display, which we argue to be “more than the sum of the two.” We introduce and motivate a classification system applicable to such audiovisual displays and categorize a corpus of 57 academic publications that appeared between 2011 and 2023 in categories such as reading level, dataset type, or evaluation system, to mention a few. The corpus also enables a meta-analysis of the field, including regularly occurring design patterns such as type of visualization and sonification techniques, or the use of visual and auditory channels, showing an overall diverse field with different designs. An analysis of a co-author network of the field shows individual teams without many interconnections. The body of work covered in this STAR also relates to three adjacent topics: audiovisual monitoring, accessibility, and audiovisual data art. These three topics are discussed individually in addition to the systematically conducted part of this research. The findings of this report may be used by researchers from both fields to understand the potentials and challenges of such integrated designs while hopefully inspiring them to collaborate with experts from the respective other field.

  • 24.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Physical Model of the Slide Guitar: An Approach Based on Contact Forces2012In: Proceedings of Audio Engineering Society Convention 132, 2012Conference paper (Refereed)
    Abstract [en]

    In this paper we approach the synthesis of the slide guitar, which is a particular play mode of the guitar where continuous tuning of the tones is achieved by sliding a metal orglass piece, the bottleneck, along thestrings on the guitar neck side. The bottleneck constitues a unilateral constraint for the string vibration.Dynamics is subject to friction, scraping, textured displacement and collisions. The presented model is physically inspired and is based on a dynamic model of friction, together with a geometrical model of the textured displacements and a model for collisions of the string with the bottlenck. These models are suitablefor implementation in a digital waveguide computational scheme for the 3D vibration of the string, where continuous pitch bending is achieved by allpass filters to approximate fractional delays, friction is captured by nonlinear state-space systems in the slide junction and textured displacements by signal injection at avariable point in the waveguide.

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  • 25.
    Evangelista, Gianpaolo
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Physical Model of the String-Fret Interaction2011In: Proc. of Digital Audio Effect Conf., 2011, p. 345-351.Conference paper (Refereed)
    Abstract [en]

    In this paper, a model for the interaction of the strings with the frets in a guitar or other fretted string instruments is introduced. In the two-polarization representation of the string oscillations it is observed that the string interacts with the fret in different ways. While the vertical oscillation is governed by perfect or imperfect clamping of the string on the fret, the horizontal oscillation is subject to friction of the string over the surface of the fret. The proposed model allows, in particular, for the accurate evaluation of the elongation of the string in the two modes, which gives rise to audible dynamic detuning. The realization of this model into a structurally passive system for use in digital waveguide synthesis is detailed. By changing the friction parameters, the model can be employed in fretless instruments too, where the string directly interacts with the neck surface.

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  • 26.
    Evangelista, Gianpaolo
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Smith III, Julius Orion
    CCRMA, Stanford University, California, USA.
    Structurally Passive Scattering Element for Modeling Guitar Pluck Action2010In: Proc. of Digital Audio Effect Conf., Graz, Austria, 2010, p. 10-17Conference paper (Refereed)
    Abstract [en]

    In this paper we propose new models for the plucking interaction of the player with the string for use with digital waveguide simulation of guitar. Unlike the previously presented models, the new models are based on structurally passive scattering junctions,which have the main advantage of being properly scaled for use infixed-point waveguide implementations and of guaranteeing stability independently of the plucking excitation. In a first model we start from the Cuzzucoli-Lombardo equa-tions [1], within the Evangelista-Eckerholm [2] propagation formulation, in order to derive the passive scattering junction by means of bilinear transformation. In a second model we start from equations properly modeling the finger compliance by means of a spring. In a third model we formalize the interaction in terms ofdriving impedances. The model is also extended using nonlinear (feathering) compliance models.

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  • 27.
    Falk, Martin
    et al.
    VISUS – Visualization Research Center, Universität Stuttgart.
    Seizinger, A.
    VISUS – Visualization Research Center, Universität Stuttgart.
    Sadlo, F.
    VISUS – Visualization Research Center, Universität Stuttgart.
    Üffinger, M.
    VISUS – Visualization Research Center, Universität Stuttgart.
    Weiskopf, D.
    VISUS – Visualization Research Center, Universität Stuttgart.
    Trajectory-Augmented Visualization of Lagrangian Coherent Structures in Unsteady Flow2010In: International Symposium on Flow Visualization (ISFV14), 2010Conference paper (Other academic)
    Abstract [en]

    The finite-time Lyapunov exponent (FTLE) field can be used for many purposes, from the analysis of the predictability in dynamical systems to the topological analysis of timedependent vector fields. In the topological context, the topic of this work, FTLE ridges represent Lagrangian coherent structures (LCS), a counterpart to separatrices in vector field topology. Since the explicit vector field behavior cannot be deduced from these representations, they may be augmented by line integral convolution patterns, a computational flow visualization counterpart to the surface oil flow method. This is, however, strictly meaningful only in stationary vector fields. Here, we propose an augmentation that visualizes the LCS-inducing flow behavior by means of complete trajectories but avoids occlusion and visual clutter. For this we exploit the FTLE for both the selection of significant trajectories as well as their individual representation. This results in 3D line representations for 2D vector fields by treating 2D time-dependent vector fields in 3D space-time. We present two variants of the approach, one easing the choice of the finite advection time for FTLE analysis and one for investigating the flow once the time is chosen.

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  • 28.
    Fernstad, Sara Johansson
    et al.
    Newcastle Univ, England.
    Johansson Westberg, Jimmy
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    To Explore What Isnt There-Glyph-Based Visualization for Analysis of Missing Values2022In: IEEE Transactions on Visualization and Computer Graphics, ISSN 1077-2626, E-ISSN 1941-0506, Vol. 28, no 10, p. 3513-3529Article in journal (Refereed)
    Abstract [en]

    This article contributes a novel visualization method, Missingness Glyph, for analysis and exploration of missing values in data. Missing values are a common challenge in most data generating domains and may cause a range of analysis issues. Missingness in data may indicate potential problems in data collection and pre-processing, or highlight important data characteristics. While the development and improvement of statistical methods for dealing with missing data is a research area in its own right, mainly focussing on replacing missing values with estimated values, considerably less focus has been put on visualization of missing values. Nonetheless, visualization and explorative analysis has great potential to support understanding of missingness in data, and to enable gaining of novel insights into patterns of missingness in a way that statistical methods are unable to. The Missingness Glyph supports identification of relevant missingness patterns in data, and is evaluated and compared to two other visualization methods in context of the missingness patterns. The results are promising and confirms that the Missingness Glyph in several cases perform better than the alternative visualization methods.

  • 29.
    Flinck Lindström, Sebastian
    et al.
    Linköping University, Department of Computer and Information Science.
    Wetterberg, Markus
    Linköping University, Department of Computer and Information Science.
    Cloud Gaming: A QoE Study of Fast-paced Single-player and Multiplayer Games2020Independent thesis Basic level (degree of Bachelor), 10,5 credits / 16 HE creditsStudent thesis
    Abstract [en]

    Cloud computing is a way to deliver high-performance services to clients who would not usually be able to handle the computations on their own. They rely on computers in the cloud performing the calculations and therefore ease the load on the client-side. The goal of this thesis is to find what factors affect the players' experience and how they affect the player. To handle this, we have done a user-based study on cloud gaming. The users get to play a fast-paced single-player game and a fast-paced multiplayer game against each other, while we collect data about their experiences. During the tests, we manipulated the players' network conditions, and afterward, they answered questions regarding their quality of experience.

    From the data collected, we can see that the frame age is the most important measurement for determining the players' in-game performance as well as the quality of experience. We are also able to see that from the quality of service measurements manipulated, the latency is the one affecting the player the most.

    Results from the multiplayer test would indicate that we can equalize the skill difference between the players without affecting the players quality of experience too much. These results are based on the advantage in ping time as well as frame age.

    From a developers perspective, this thesis emphasized the need to take frame age into account, and to try to manipulate the different parts of the frame age. The goal would be to ultimately lower the frame age and make the gaming experience more enjoyable for the player.

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  • 30.
    Flinck Lindström, Sebastian
    et al.
    Linköping University.
    Wetterberg, Markus
    Linköping University.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Cloud Gaming: A QoE Study of Fast-paced Single-player and Multiplayer Gaming2020In: 2020 IEEE/ACM 13TH INTERNATIONAL CONFERENCE ON UTILITY AND CLOUD COMPUTING (UCC 2020), Institute of Electrical and Electronics Engineers (IEEE), 2020, p. 34-45Conference paper (Refereed)
    Abstract [en]

    Cloud computing offers an attractive solution for modern computer games. By moving the increasingly demanding graphical calculations (e.g., generation of realtime video streams) to the cloud, consumers can play games using small, cheap devices. While cloud gaming has many advantages and is increasingly deployed, not much work has been done to understand the underlying factors impacting players user experience when moving the processing to the cloud. In this paper, we study the impact of the quality of service (QoS) factors most affecting the players quality of experience (QoE) and in-game performance. In particular, these relationships are studied from multiple perspectives using complementing analysis methods applied on the data collected via instrumented user tests. During the tests, we manipulated the players network conditions and collected low-level QoS metrics and in-game performance, and after each game, the users answered questions capturing their QoE. New insights are provided using different correlation/auto-correlation/cross-correlation statistics, regression models, and a thorough break-down of the QoS metric most strongly correlated with the users QoE. We find that the frame age is the most important QoS metric for predicting in-game performance and QoE, and that spikes in the frame age caused by large frame transfers can have extended negative impact as they can cause processing backlogs. The study emphasizes the need to carefully consider and optimize the parts making up the frame age, including dependencies between the processing steps. By lowering the frame age, more enjoyable gaming experiences can be provided.

  • 31.
    Flinke, Johan
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Utvärdering och testning av ett bildbehandlingsprogram för volymberäkning av mat i nutritionsforskning2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vid ett forskningsarbete som bedrivs om barnfetma finns det ett intresse av att säkerställa den mängd mat som deltagarna konsumerar. För att komma runt problematiken med felbedömningar kring det faktiska födointaget har det tagits fram ett program som med hjälp av stereoskopisk bildbehandling ska kunna göra volymberäkningar baserade på fotografier av deltagarnas måltider. På så sätt elimineras den felmarginal som den mänskliga faktorn kan stå för genom att låta en dator ta fram den exakta mängden föda som konsumerats och det ger även en ökad möjlighet att lagra den insamlade datamängden för framtida studier.

    Det här arbetet syftar till att evaluera programmet FoodIQ som tagits fram speciellt för detta ändamål. Även om programmet har levererats och tagits i bruk, så har det ännu inte gjorts några omfattande tester som kan verifiera att programmet klarar av att mäta volymer korrekt. Huvuddelen av det här arbetet har bestått i att genomföra ett stort antal volymberäkningar för att på så sätt kunna få en uppfattning om programmets grad av noggrannhet.

    De slutsatser som kunde dras var att även om programmet visar upp en stor potential så lider det av några allvarliga brister som gör att det i dagsläget inte fungerar som det är tänkt. I den här rapporten kommer det att redogöras en del kring programmets användarvänlighet samt funktionalitet . Det kommer även att presenteras resultatet av de tester som genomfördes där syftet var att försöka ta reda på vilka faktorer som avgör huruvida en volymmätning fungerar som det är tänkt eller inte.   

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  • 32.
    Fransson, Sarah
    et al.
    Linköping University, Faculty of Medicine and Health Sciences.
    Corrow, Sherryse
    Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada; Bethel Univ, MN 55112 USA.
    Yeung, Shanna
    Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada.
    Schaefer, Heidi
    Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada.
    Barton, Jason J. S.
    Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada; Univ British Columbia, Canada.
    Effects of Faces and Voices on the Encoding of Biographic Information2022In: Brain Sciences, ISSN 2076-3425, E-ISSN 2076-3425, Vol. 12, no 12, article id 1716Article in journal (Refereed)
    Abstract [en]

    There are multiple forms of knowledge about people. Whether diverse person-related data interact is of interest regarding the more general issue of integration of multi-source information about the world. Our goal was to examine whether perception of a persons face or voice enhanced the encoding of their biographic data. We performed three experiments. In the first experiment, subjects learned the biographic data of a character with or without a video clip of their face. In the second experiment, they learned the characters data with an audio clip of either a generic narrators voice or the characters voice relating the same biographic information. In the third experiment, an audiovisual clip of both the face and voice of either a generic narrator or the character accompanied the learning of biographic data. After learning, a test phase presented biographic data alone, and subjects were tested first for familiarity and second for matching of biographic data to the name. The results showed equivalent learning of biographic data across all three experiments, and none showed evidence that a characters face or voice enhanced the learning of biographic information. We conclude that the simultaneous processing of perceptual representations of people may not modulate the encoding of biographic data.

  • 33.
    Fritz, Jenny
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Utveckling av ett verktyg för produktkataloggenerering2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today, product catalogs are published and distributed by a large share of retail companies.However, the process of catalog production can be both time consuming and resource heavy.The purpose of this thesis has been to find a solution to that problem. This was done byresearching different needs and demands regarding catalog production which was then followedby implementation of a software tool that could accomodate those needs. The goal was toautomatically produce a product catalog in PDF format out of an existing product database.A pilot study showed that despite differences in existing catalog layouts, there still aresome common elements such as product image and price. This was used as a basis during theimplementation in which it was assumed that a product database, no matter the type of datasource, always contains specific information elements to be published. To allow for differentlayouts of a product catalog, a separate template handler was implemented. The purposeof this was to give the user an opportunity to configure for instance text field placements,image dimensions and which background images to use - all in favor of individual needs andoppinions.To reach the goals the scope of the project was extended and during spring 2013 it wasfinalized with the desired functionalities. Despite this, a whole lot of possibilities regardingfurther development can be seen, especially since the need of a more efficient process of catalogproduction seems to exist.

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  • 34.
    Fujiwara, Takanori
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Kuo, Yun-Hsin
    Univ Calif Davis, CA USA.
    Ynnerman, Anders
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Ma, Kwan-Liu
    Univ Calif Davis, CA USA.
    Feature Learning for Nonlinear Dimensionality Reduction toward Maximal Extraction of Hidden Patterns2023In: 2023 IEEE 16TH PACIFIC VISUALIZATION SYMPOSIUM, PACIFICVIS, IEEE COMPUTER SOC , 2023, p. 122-131Conference paper (Refereed)
    Abstract [en]

    Dimensionality reduction (DR) plays a vital role in the visual analysis of high-dimensional data. One main aim of DR is to reveal hidden patterns that lie on intrinsic low-dimensional manifolds. However, DR often overlooks important patterns when the manifolds are distorted or masked by certain influential data attributes. This paper presents a feature learning framework, FEALM, designed to generate a set of optimized data projections for nonlinear DR in order to capture important patterns in the hidden manifolds. These projections produce maximally different nearest-neighbor graphs so that resultant DR outcomes are significantly different. To achieve such a capability, we design an optimization algorithm as well as introduce a new graph dissimilarity measure, named neighbor-shape dissimilarity. Additionally, we develop interactive visualizations to assist comparison of obtained DR results and interpretation of each DR result. We demonstrate FEALMs effectiveness through experiments and case studies using synthetic and real-world datasets.

  • 35.
    Glansberg, Sven
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, The Institute of Technology.
    Presentation av reservdelskatalog med modellbaserat konstruktionsunderlag: En fallstudie av Saabs konceptutveckling för teknikinformation till stridsflygplanet Gripen NG2012Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the military aerospace industry, product data management in the product lifecycle, and development of logistics support are key areas that affect management of requirements and costs. The most recent strategy for these challenges is model-based definition (MBD). The discipline of technical communication has yet to explore and exploit the potential of MBD. Expected benefits include better ways of presenting illustrations and more efficient methodologies for production.

    This problem was investigated through a case study of the concept development of technical communication for Saab's fighter aircraft Gripen NG. The study focused on the illustrated parts catalog and its use. This work contributes with a model that describes four design levels for information systems, where presentation is the one in focus. In addition, comparable practices for management of MBD data were investigated in the case.

    The study found that the technical communication department is facing a transition from document-based management to development of information systems. Furthermore, three proposals for the next generation of parts catalogs are discussed. Two conclusions were reached. First, a lack of knowledge regarding the use of the parts catalog makes it difficult to assess new ways of presentation. And second, the improvements made in methodology and presentation in other MBD applications of the product life cycle are not immediately transferable to the parts catalog. Hence, suggestions for future research and work are presented.

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  • 36.
    Gooran, Sasan
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    A Comprehensive Halftone Image Quality Evaluation of First- and Second-order FM Halftones2022In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 66, no 1, article id 010506Article in journal (Refereed)
    Abstract [en]

    Halftoning is a crucial part of image reproduction in print. For large format prints, especially at higher resolutions, it is important to have very fast and computationally feasible halftoning methods of good quality. The authors have already introduced an approach to obtain image-independent threshold matrices generating both first- and second-order frequency modulated (FM) halftones with different clustered dot sizes. Predetermined and image-independent threshold matrices make the proposed halftoning method a point-by-point process and thereby very fast. In this article, they report a comprehensive quality evaluation of first- and second-order FM halftones generated by this technique and compare them with each other, employing several quality metrics. These generated halftones are also compared with error diffusion (ED) halftones employing two different error filters. The results indicate that the second-order FM halftoning with small clustered dot size performs best in almost all studied quality aspects than the first- and second-order FM halftoning with larger clustered dot size. It is also shown that the first- and second-order FM halftones with small clustered dot sizes are of almost the same quality as ED halftones using Floyd–Steinberg error filter and of higher quality than halftones generated by ED employing Jarvis, Judice, and Ninke error filter.

  • 37.
    Gooran, Sasan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Context Dependent Color Halftoning in Digital Printing2000In: IS&Ts PICS Conference 2000, The Society for Imaging Science and Technology , 2000, p. 242-246Conference paper (Other academic)
  • 38.
    Gooran, Sasan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Context Dependent Color Halftoning with Color Matching2001In: Proceedings of the Technical Association of the Graphic Arts, TAGA, 2001, Technical Association of the Graphic Arts , 2001, p. 304-317Conference paper (Other academic)
  • 39.
    Gooran, Sasan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Halftoning and Color Noise2001In: Ninth Color Imaging Conference: Color Science and Engineering: Systems, Technologies, and Applications, The Society for Imaging Science and Technology , 2001, p. 148-188Conference paper (Other academic)
    Abstract [en]

    A frequency modulated color halftoning algorithm is presented in this paper.Unlike the normal approach of halftoning a color image,in which the color separations of the original image are halftoned independently,the original color image is halftoned in a context dependent manner.The strategy to reduce color noise and gain control over color gamut is to prevent dot-on-dot printing as much as possible. The color shifts that might occur because of this dot-off-dot printing strategy have to be compensated before halftoning. This transformation uses some data for the printer with which the halftoned color image is supposed to be printed. The experiments verify that the color noise is notably smaller in the images that are halftoned by the proposed method compared to the images halftoned using the normal approach of halftoning color images.The method also offers the possibility of treating the color separations of the original image differently if needed.For example,the yellow separation should be treated differently from the other separations, because the yellow dots are less visible than the other color dots when they are printed on a white paper.Two criteria for objectively measuring the quality of the produced results are also discussed.

  • 40.
    Gooran, Sasan
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Hybrid Halftoning in Flexography2003In: Proceedings of the Technical Association of the Graphic Arts, TAGA, Technical Association of the Graphic Arts , 2003Conference paper (Other academic)
  • 41.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Abedini, Fereshteh
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    3D Surface Structures and 3D Halftoning2020Conference paper (Refereed)
    Abstract [en]

    As 3D printing is becoming increasingly popular, the demand for high quality surface reproduction is also increasing. Like in 2D printing, halftoning plays an important role in the quality of the surface reproduction. Developing advanced 3D halftoning methods for 3D printing and adapting them to the structure of the surface is therefore essential for improving surface reproduction quality. In this paper, an extension of an iterative 2D halftoning method to 3D is used to apply different halftone structures on 3D surfaces. The results show that using different halftones based on the 3D geometrical structure of the surface and/or the viewing angle in combination with the structure of the texture being mapped on the surface can potentially improve the quality of the appearance of 3D surfaces.

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  • 42.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Abedini, Fereshteh
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Three-Dimensional Adaptive Digital Halftoning2022In: Journal of Imaging Science and Technology, ISSN 1062-3701, E-ISSN 1943-3522, Vol. 66, no 6, article id 060403Article in journal (Refereed)
    Abstract [en]

    Two-and-a-half and 3D printing are becoming increasingly popular, and consequently the demand for high quality surface reproduction is also increasing. Halftoning plays an important role in the quality of the surface reproduction. Three dimensional halftoning methods, that adapt the halftone structures to the geometrical structure of 3D surfaces or to the viewing direction, could further improve surface reproduction quality. In this paper, a 3D adaptive halftoning method is proposed, that incorporates different halftone structures on the same 3D surface. The halftone structures are firstly adapted to the 3D geometrical structure of the surface. Secondly, the halftone structures are adapted based on the normal vector to the surface at a specific voxel. Two simple approaches to approximate the normal vector are also proposed. The problem of edge artefacts that might occur in the previously proposed 3D Iterative Method Controlling the Dot Placement (IMCDP) halftoning method is discussed and a solution to reduce these artefacts is given. The results show that the proposed adaptive halftoning can combine different halftone structures on the same 3D surface with no transition artefacts between different halftone structures. It is also shown that using second-order frequency modulation (FM) halftone, in comparison to first-order FM, can result in more homogeneous appearance of 3D surfaces with undesirable structures on them. (C) 2022 Society for Imaging Science and Technology.

  • 43.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering.
    Hauck, Shahram
    Dept. of Informatics and Media, Beuth Hochschule Berlin University of Applied Sciences, Berlin, Germany,.
    A novel spectral trapping model for color halftones2018In: Journal of Print and Media Technology Research, ISSN 2223-8905, E-ISSN 2414-6250, Vol. 7, no 3, p. 107-113Article in journal (Refereed)
    Abstract [en]

    The amount of trapping has a great impact on the gray balance and color reproduction of printed products. The conventional trapping models are print density based and give percentage values to estimate the effect of trapping. In an earlier paper (Hauck and Gooran, 2011), a spectral trapping model was proposed, that defines the trapping effect as the DE* ab colorimetric differences between the real ink overlap (measurements) and the ideal ink overlap. All the trapping models proposed so far, however, only calculate the trapping value for full-tone (solid) ink overlap. As the trapping value for full-tone ink overlap could be overestimating the actual ink trapping effect for halftones, it is important to be able to also approximate the trapping value of color halftones. Furthermore, for a detailed gray balance shift analysis, there is a need to estimate the trapping effect for specific color halftones.

    In the present paper, we propose a novel spectral trapping model that delivers the trapping value as DE* ab color difference for color halftones taking into account secondary and tertiary ink overlap.

    The results of the experiments show that the trapping value for color halftones are much smaller than their corresponding trapping value at full-tone, but trapping value of halftones, besides other common quality parameters, should still be considered if some quality inaccuracy, such as gray balance shift, occurs in a print production.

  • 44.
    Gooran, Sasan
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Kruse, Björn
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Color Halftoning in Digital Printing1999Conference paper (Other academic)
  • 45.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Kruse, Björn
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    High-speed first- and second-order frequency modulated halftoning2015In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 24, no 2Article in journal (Refereed)
    Abstract [en]

    Halftoning is a crucial part of image reproduction in print. First-order FM halftones, in which the single dots are stochastically distributed, is widely used in printing technologies, such as inkjet, that are able to stably print isolated dispersed dots. Printers, such as laser printers, that utilize electrophotographic technology are not able to stably print the isolated dots and therefore use clustered-dot halftones. Periodic clustered-dot, i.e. AM, halftones are commonly used in this type of printers but they suffer from undesired periodic interference pattern called moiré. An alternative solution is to use second-order FM halftones in which the clustered dots are stochastically distributed. The iterative halftoning techniques, that usually result in well-formed halftones, are operating on the whole input image and require extensive computations and thereby are very slow when the input image is large. In this paper, we introduce a method to generate image independent threshold matrices for first and second-order FM halftoning. The first-order threshold matrix generates well-formed halftone patterns and the second-order FM threshold matrix can be adjusted to produce clustered-dots of different size, shape and alignment. Using predetermined and image independent threshold matrices makes the proposed halftoning method a point-by-point process and thereby very fast.

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  • 46.
    Gooran, Sasan
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Kruse, Björn
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Near-optimal model-based halftoning technique with dot gain1998In: SPIE Volume 3308 - Very High Resolution and Quality Imaging III, SPIE - International Society for Optical Engineering, 1998Conference paper (Other academic)
    Abstract [en]

    We present a novel halftoning technique for transformation of continuous tone images into binary halftoned separations. The algorithm is based on a successive assessment of the near optimum sequence of positions to render. The impact of each rendered point is fed back to the process as a distribution function thereby influencing the following evaluations. The distribution function is not constant over the density range. In order to be able to separate the dots adequately in the highlights the 'width or radius' of the distribution has to be made larger than in the mid-tones. The human visual system and the effect of dot gain are also taken into account in this algorithm. The notion of incremental dot gain is introduced. Since the series of positions to render are not known in advance the final necessary dot gain compensation is impossible to assess. However the incremental dot gain can be computed in advance for each configuration of dots and taken into account in the process of generating the output. Some aspects of the process have certain resemblance with error distribution based algorithms. However the raster scanning sequence of rendering the output points in usual error diffusion algorithms is completely different from the image dependent traversal described in this paper.

  • 47.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Yang, Li
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Basics of tone reproduction2015In: Handbook of Digital Imaging / [ed] Michael Kriss, Wiley , 2015Chapter in book (Refereed)
    Abstract [en]

     There is no doubt that printing has been one of the most important technological inventions for

    human civilization. Books, magazines, news papers, and so on have been printed for different

    purposes such as distributing knowledge, thoughts, and news and commercializing products.

    Tone reproduction for images has been one of the challenging parts of the printing technology

    because the printing devices are restricted to a few color inks, whereas the original image

    may consist of millions of color tones. In this chapter, the basics of the tone reproduction

    are introduced. We begin with a brief history of halftoning and a short introduction of digitalization.

    It is followed by the description on visual acuity of human visual system and its

    relationship with the screen resolution. Then the basic and general concepts of tone reproduction,

    such as screen frequency, print resolution, screen angle and Moiré pattern, and dot gain

    are described and illustrated. Dot gain is only briefl y described and illustrated in this chapter as

    it is thoroughly discussed in Physical Evaluation of the Quality of Color Halftone . Finally,

    technologies for color reproduction and color halftoning are discussed.

  • 48.
    Gooran, Sasan
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Yang, Li
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Frequency Modulated Halftoning and Dot Gain2004In: Proceedings of the Technical Association of the Graphic Arts, TAGA, Technical Association of the Graphic Arts , 2004Conference paper (Other academic)
  • 49.
    Gooran, Sasan
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Österberg, Mats
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Kruse, Björn
    Linköping University, Department of Electrical Engineering. Linköping University, The Institute of Technology.
    Hybrid Halftoning: A novel Algorithm for Using Multiple Halftoning Technologies1996Conference paper (Refereed)
    Abstract [en]

    The rendering quality in halftoning is a critical issue. The quality aspects are more important in some images than in others. The quality of skin tone rendering of halftoned images generated by frequency modulated (FM) halftoning techniques differs from those generated by conventional halftoning techniques. Some judge the conventional halftoning techniques as superior in smoothly varying tones whereas frequency modulated halftoning techniques excel in heavily textured images. This paper describes an algorithm that can incorporate both technologies simultaneously. The technique is an iterative optimization of the binary halftone image with respect to the differences between the original and the halftoned images. The performance of the algorithm can be controlled by the nature of the original state of the iteration. The algorithm can in effect accommodate any type of halftone that can be described by a threshold matrix.

  • 50.
    Guo, Jun
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.
    Further development of shaders for realistic materials and global illumination effects2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Shader programming is important for realistic material and global illumination real-time rendering, especially in 3D industrial fields nowadays, more and more customers of Visual Components Oy, a Finnish 3D software company have been found to be no longer only content with the correct simulation result, but also the result of realistic real-time rendering. This thesis project will provide a deep research on real world material classification, property definition and global illumination techniques in industrial fields. On the other hand, the Shader program for different materials and global illumination techniques are also created according to the classification and definition in this thesis work. Moreover, an external rendering tool Redway3D is evaluated as the reference and regarded as the considerable solution in the future development work.

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