How to find the intensity of each pixel of an image?

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shimul 2013-9-6

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https://ww2.mathworks.cn/matlabcentral/answers/86484-how-to-find-the-intensity-of-each-pixel-of-an-image

编辑： Image Analyst 2018-4-2

Consider an image sample.jpg Now I want to count the number of pixels on that image have intensity value larger than 200(white pixels).

If the image contain such pixels above 75% then I want to reject the image. How can I accomplish this in matlab?

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Doug Hull 2013-9-6

What format is the image in? RGB or greyscale? If it is just a greyscale image, it is really just a matrix and you can do any calculations on it like you would any matrix in MATLAB.

shimul 2013-9-13

Yap I have done this. However thanks

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Image Analyst 2013-9-6

2
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/86484-how-to-find-the-intensity-of-each-pixel-of-an-image#answer_96026

编辑：Image Analyst 2013-9-6

在 MATLAB Online 中打开

If it's a color image, first convert to a gray image

[rows, columns, numberofColorChannels] = size(originalImage);
if numberofColorChannels > 1
  grayImage = rgb2gray(originalImage);
else
  grayImage  = originalImage;
end

otherwise if it's already gray, you don't need to call rgb2gray(). Then threshold

binaryImage = grayImage >= 200;

Then count

numberOfWhitePixels = sum(binaryImage(:));

Note: MATLAB uses the American spelling of gray, not the English spelling of grey.