using the attached color image and ROI mask and how can I remove the background from the image and retain only the approximate ROI.

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the color image must have the dark background in the output image.

Accepted Answer

Matt Gaidica
Matt Gaidica on 12 Dec 2021
IM = imread('ROI.png');
mask = logical(imread('mask.png'));
rmMask = bsxfun(@times, IM, cast(mask, 'like', IM));
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Nosipho Majola
Nosipho Majola on 12 Dec 2021
Edited: Nosipho Majola on 12 Dec 2021
Thank you Matt. Would you please help me out with a code that does not use built-in functon but still does the same thing? i.e. not using bsxfun()

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More Answers (1)

Image Analyst
Image Analyst on 12 Dec 2021
Edited: Image Analyst on 12 Dec 2021
Looks like you've accepted Matt's answer so you probably don't need this but
rgbImage = imread('ROI.png');
mask = logical(imread('mask.png'));
% Make mask 3-D
mask = cat(3, mask, mask, mask);
rgbImage(~mask) = 0;
I haven't tested it but that will probably work. If it's not your homework, try that.
If it's your homework then you may not be able to use imread(), cat(), logical(), imshow(), etc. so see this link:
and of course you wouldn't be able to use our code either - that would be even worse than using built-in functions and you could face disciplinary action.
Image Analyst
Image Analyst on 12 Dec 2021
OK, well if you run my demo with images called image1 and image2, it should look identical to the screenshot I posted in my last comment. If you alter it (like to handle your image names, or display things somewhat differently) and it doesn't work, then post your screenshot, two original images with the paperclip icon, and your code and I'll fix it.

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