Matlab - How to hide a three-dimensional image using a binary image

Question

I have an image with a red, green, blue channel and a binary version of the image.

What I want to do is combine these 2 images so that the binary image works like a mask for a regular image.

I want to select only pixels from a color image that are 1 in binary format.

I know this should work with cat or even repmat , but since I'm pretty new to Matlab, I can't figure out how to do this even after reading the function docs.

Answer 1

If you have a three-dimensional image I and a binary mask M , you can mask the non-essential bits by zero or by multiplying the image by the mask:

 I = bsxfun(@times, I, M); 

or by logical indexing:

 I(~mask(:, :, ones(1, size(I, 3)))) = 0; 

Answer 2

I am not 100% sure, I understand your problem, but here comes one suggestion:

Suppose rgbIm is your RGB image and bwIm is your binary image;

You can try to “deploy” your binary image to “3D” (so that its size matches the original RGB image) with the following line of code:

 bwImAux = bwIm(:,:,[1 1 1]); 

And then do a simple multiplication to “eliminate” all the pixels that are not in the binary image:

 rgbImNew = rgbIm.*bwImAux; 

Hope this helps.

Answer 3

You can use a binary image as a logical index in a 3dim image. To reset all pixels in an image that are zero in the binary mask , you can use the following code for each dimension: image(~mask)=0;