MATLAB: What should I do so that only gray image converts into binary , not the black backgroung while moving the threshold.

Image Processing Toolboxthresholdthresholding a gray image and converting into binary

Dear Image analyst , I have a gray image ( a selected ROI) displayed in a black background screen. I am trying to use your adjustable threshold method to convert this gray image into binary.while moving the threshold cursor to convert this gray image into binary image , the black background is also changing from black to white and is including into total pixel calculations and in histogram. But I want only my ROI to convert from gray to binary not the background.

Best Answer

Just change your thresholds. Instead of going from 0 to 150, go from 150 to 255. If that's not right, post a screenshot and describe it in more detail.

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MATLAB: I exactly want to do same thing explained in “what should I do so that only gray image converts into binary , not the black backgroung while moving the threshold.” question. But when I count white and black pixels in ROI I am getting 0.

I don't understand the question you quoted (due to bad grammar), and don't understand yours either. But I think you want this:

numWhitePixels = sum(filledBinaryImage(:));
numBlackPixels = numel(filledBinaryImage) - numWhitePixels ;

MATLAB: How to change white background to black and black foreground to white

The logical not operator is ~ (or you can use not):

invertedI = ~BW
%or
invertedI = not(BW)

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Related Solutions

MATLAB: I exactly want to do same thing explained in “what should I do so that only gray image converts into binary , not the black backgroung while moving the threshold.” question. But when I count white and black pixels in ROI I am getting 0.

MATLAB: How to change white background to black and black foreground to white

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