how to get adaptive contrast enhancement transformation of the gray image ?

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kalaivaani 2013-8-29

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https://ww2.mathworks.cn/matlabcentral/answers/85886-how-to-get-adaptive-contrast-enhancement-transformation-of-the-gray-image

can this be done without using adapthisteq()?

the local variation of the lesions obtained by

g=255((sigmoid(color)-sigmoid(graymin))/(sigmoid(graymax) - sigmoid(graymin)) where # * sigmoid(color) = 1/(1+exp((mean - colorimage)/variance) # * sigmoid(graymin) is the min sigmoid value of the grayimage # * sigmoid(graymax) is the max sigmoid value of the grayimage

how can i get colorimage subtracted from meanimage which is grayscale

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Image Analyst 2013-8-29

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Sure, you can do almost whatever you want if you write it yourself. You can make a color image out of a grayscale image and then subtract:

grayImage3D = cat(3, grayImage, grayImage, grayImage);
% Cast to float to avoid clipping at 0.
newImage = double(rgbImage) - double(grayImage3D);  % It's floating point now.

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kalaivaani 2013-8-30

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Gmax is the maximum intensity value of greenchannel image(1*700) varianceimage &meanimage are greenchannel images (605*700)

??? Undefined function or method 'exp' for input arguments of type
'uint8'.
Error in ==> Untitled2 at 30
fmax = 1./(1+exp((uint8(meanimage)
-uint8(Gmax)))./uint8(varianceimage));