How to convert the green pixels to white?

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charuleelaa vanilavarasu 2016-3-20

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https://ww2.mathworks.cn/matlabcentral/answers/274568-how-to-convert-the-green-pixels-to-white

评论： Image Analyst 2016-3-21

Screenshot 2016-03-21 00.21.47.png

I have this image labelled dark green(In the image attached). I want to turn all of the pixels that are not black to white. How do i do that?

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Walter Roberson 2016-3-20

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Answer 1

Walter Roberson 2016-3-20

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https://ww2.mathworks.cn/matlabcentral/answers/274568-how-to-convert-the-green-pixels-to-white#answer_214355

在 MATLAB Online 中打开

%black pixels have 0 for all 3 components, R, G, B. So a non-black pixel has at least one non-0 component
mask = any(YourRGBImage,3);     %true if any component is non-zero
%now that we know which ones are non-black, make those pixels white
%ah, short-cut: since logical true is 1 and white is 1, and logical false is 0 and black is 0
%we can just use the mask itself as the black / white image
maskedImage  = double(repmat(mask, 1, 1, 3));

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charuleelaa vanilavarasu 2016-3-21

syntax error. fixed it! thank you!

charuleelaa vanilavarasu 2016-3-21

编辑：charuleelaa vanilavarasu 2016-3-21

How do i do the reverse? i.e Turn all the black pixels white? would imcomplement work?

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Answer 2

Image Analyst 2016-3-21

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I hve several color segmentation demos in my File Exchange. http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 Adapt one of them to find pixels that you consider to be of a roughly or exactly "green" color. This will give you a mask of what pixels are green.

If you really want to "I want to turn all of the pixels that are not black to white." then it really doesn't matter if they're green or purple or yellow or any other color to start with, does it? In that case, use Walter's code to turn non-pure-black pixels to white.

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charuleelaa vanilavarasu 2016-3-21

编辑：Walter Roberson 2016-3-21

在 MATLAB Online 中打开

Image1=im2double(filt);% filt is the filtered image 
[row column page] = size(Image1)
mask = Image1(:,:,2) > Image1(:,:,1) & Image1(:,:,2) > Image1(:,:,3);
Image2 = Image1 .* mask(:,:,[1 1 1]);
figure,imshow(Image2);
title('light green');
mask = Image2(:,:,2) + 50 > Image2(:,:,1) & Image2(:,:,2) + 50 > 
Image2(:,:,3);
Image3 = Image2 .* mask(:,:,[1 1 1]);
figure,imshow(Image3);
title('dark green');