Automatic Exposure Correction And Local Contrast Setting For Diagnostic Viewing of Medical X-ray Images
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
To properly display digital X-ray images for visual diagnosis, a proper display range needs to be identified. This can be difficult when the image contains collimators or large background areas which can dominate the histograms. Also, when there are both underexposed and overexposed areas in the image it is difficult to display these properly at the same time. The purpose of this thesis is to find a way to solve these problems. A few different approaches are evaluated to find their strengths and weaknesses. Based on Local Histogram Equalization, a new method is developed to put various constraints on the mapping. These include alternative ways to perform the histogram calculations and how to define the local histograms. The new method also includes collimator detection and background suppression to keep irrelevant parts of the image out of the calculations. Results show that the new method enables proper display of both underexposed and overexposed areas in the image simultaneously while maintaining the natural look of the image. More testing is required to find appropriate parameters for various image types.
Place, publisher, year, edition, pages
2010. , 53 p.
image processing, weight, histogram equalization, digital X-ray image, contrast setting, local
Medical Laboratory and Measurements Technologies
IdentifiersURN: urn:nbn:se:liu:diva-56630ISRN: LiTH-IMT/MI30-A-EX--10/491--SEOAI: oai:DiVA.org:liu-56630DiVA: diva2:320764
Subject / course
Andersson, MatsSpies, Hagen
Knutsson, Hans, Professor