MATLAB: How to compute Correlation of red- and green-channel pixel values of skin lesion area

correlationenergyfeatures extractionimage processingImage Processing Toolboxlesionrgb

I need to compute six correlation coefficients (red-green, green-blue, blue-red, red-grey, green-grey, and blue-grey) for both the whole sub-image and the lesion area respectively,one example shall do it for the 6 as of the same logic shall be applied,as well as calculating the Energy based on color extraction not texture or regionprops one(R,G,B,Gray) but one color space example shall do.. thanks

Best Answer

Did you try corr()?

coeff = corr(redChannel(:), greenChannel(:));

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MATLAB: I am doing work on detection of malarial parasite. red blood cell extraction is the part of this project.

Try this:

% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
redMask = redChannel >= 170;
greenMask = greenChannel >= 150 & greenChannel <= 201;
blueMask = blueChannel >= 160 & blueChannel <= 220;
mask = redMask & greenMask & blueMask;
% Mask channels
redChannel(~mask) = 255;
greenChannel(~mask) = 255;
blueChannel(~mask) = 255;
% Recombine separate masked color channels into a single, true color RGB image.
maskedRgbImage = cat(3, redChannel, greenChannel, blueChannel);
% maskedRgbImage is what the paper calls "g"

This code won't work unless your color gamut is the same as what they have. In other words if the color temperature (white balance) of your lighting and the exposure (brightness) don't match their values, then you'd need to use different threshold numbers. I usually don't like color segmentation in RGB space because of those reasons, unless you know that you will have very reproducible/stable lighting and subject.

MATLAB: How to extract RGB information from an segmented image excluded white background.

Get a mask of where white is, then extract pixels from where it's not white

% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
whiteMask = redChannel == 255 & greenChannel  == 255 & blueChannel == 255;
redValues = redChannel(~whiteMask);
greenValues = greenChannel(~whiteMask);
blueValues = blueChannel(~whiteMask);

Best Answer

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MATLAB: I am doing work on detection of malarial parasite. red blood cell extraction is the part of this project.

MATLAB: How to extract RGB information from an segmented image excluded white background.

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