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

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Leow Bin 2017-7-22

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https://ww2.mathworks.cn/matlabcentral/answers/349840-how-to-extract-rgb-information-from-an-segmented-image-excluded-white-background

评论： Image Analyst 2017-7-22

Hi, I am working on project about image processing. I would like to know about how to extract the RGB information from an segmented image excluded the white background. I only need the RGB value for my region of interest, and I don't want the white pixels RGB value to exist in my data file. Thank you.

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Answer 1

Image Analyst 2017-7-22

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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);

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Leow Bin 2017-7-22

Thanks for your kindly help~that's the exactly what I needed.

Image Analyst 2017-7-22

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Note, if white is just bright areas, then you don't have to use just pure 255, it can be any values above some intensity that you consider "white", so for example you can do:

whiteMask = redChannel >= 200 & greenChannel >= 225 & blueChannel >= 230;

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Answer 2

KALYAN ACHARJYA 2017-7-22

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https://ww2.mathworks.cn/matlabcentral/answers/349840-how-to-extract-rgb-information-from-an-segmented-image-excluded-white-background#answer_275137

编辑：KALYAN ACHARJYA 2017-7-22

You can directly calculate the R G B from the image, Apply If R=255, G=255, B=255, then ignore the region else ...do your program. Similar Image is needed for more clarification.

Please note: I am beginner in Matlab