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Skin Lesion Surface Area and Erythema Intensity Calculation for PASI Determination using Stereo Vision

Jonker, L.M. (2019) Skin Lesion Surface Area and Erythema Intensity Calculation for PASI Determination using Stereo Vision.

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Abstract:There are several tools to determine the severity of psoriasis and to track the effect of treatment, one of which is Psoriasis Area and Severity Index (PASI). PASI score calculation needs an accurate lesion area to total skin area ratio. To accurately determine these areas, 3D reconstruction from stereo vision has been used. Disparity maps and consecutively point clouds of the object of interest were made from stereo pictures. The object for testing this method has been the arm. Transforming the colour space from red, green and blue (RGB) to YCbCr (Y:luminance; Cb: chrominance-blue; Cr: chrominance-red) and inspecting the point clouds of each separate component, provides detection of red and lighter lesions. A point cloud of these lesions can then be made. Using Delaunay triangulation on the point clouds results in a mesh of which the area can be calculated. Tests have been conducted on light and dark skin shades, with red and pink lesions. It has also been tested for multiple lesions placed a few centimetres apart. The test results showed that the formulated method works on both light and dark shade skin for red lesions, and detection of multiple lesions can be done as well. The method does not perform as well on lighter, pink lesions. The calculated lesion areas differed to the actual areas with an average factor of +37.45%.
Item Type:Essay (Bachelor)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:50 technical science in general
Programme:Electrical Engineering BSc (56953)
Link to this item:http://purl.utwente.nl/essays/78992
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