Greyscale an image via replacing pixels

Question

Anna 2013-8-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/84115-greyscale-an-image-via-replacing-pixels

I have an image that I want to greyscale. It contains only blue and white pixels and I want to use a method whereby I identify the blue pixels and make them grey. How can I do that?

So far I have got:

fit = imread('RGB.jpg');
size(fit)
imshow(fit);

So I haven't got very far. I have created a function to test if a pixel is blue. Is there any way to use this? An example of using pixels to replace would be much appreciated.

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Ashish Uthama 2013-8-6

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Answer 1

Ashish Uthama 2013-8-6

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/84115-greyscale-an-image-via-replacing-pixels#answer_93692

在 MATLAB Online 中打开

 % air code (untested) 
 red   = fit(:,:,1); 
 green = fit(:,:,2);
 blue  = fit(:,:,3);
 isblue = blue>250;
 % Use logical indexing to set the red and green channels to be the same value as the blue channel. (When R==G==B, then the color is 'gray')
 red(isblue)   = blue(isblue);
 green(isblue) = blue(isblue);
 % reassemble
 fitout = cat(3, red, green, blue)