Image Preprocessing

Image Preprocessing

Multiple test cases gave much trouble due to various issues with the quality of the picture taken. The most notorious issue was that of nonuniform and poor lighting.

Image Lighting Adjustment

The method used to adjust lighting was through a morphological opening. This generates a image which makes obvious which regions of the image are darker than others (higher gray level) and from that, we can 'subtract' excess gray levels in the images. It was found to be of little use; the lighting is simply too uneven sometimes, and the method assumes the only variation in darkness (gray level) in the image is due to the lighting.




 A example of the built in matlab demo; works perfectly to demonstrate the concept.

Final Black and White Output

Using the given operation on our poorly lit sample. Not particularly helpful.

 

Final Black and White Output

Final algoithm

We did not use any lighting adjustments at the end due to the fact that grayscale image take away much of the information of the skin that we are interested. We could have used some of the noise filter such as Weiner adaptive low-pass filter to get better results here.