Add the three channels in a image to obtain a color image MATLAB

Question

I am modifying images in matlab and I have a problem.

I need to separate the 3 channels of color and modify them separately.

I use this to obtain the three chann

Answer 1

You are adding the values of the three layers instead of concatenating them in a 3D array.

Try this:

A= cat(3, a(:,:,1), a(:,:,2), a(:,:,3));

I should also note that you can edit the layers simply by indexing, say you want to switch the red and green components:

I1 = imread('http://i.stack.imgur.com/1KyJA.jpg');
I2=I1;
I2(:,:,1)=I1(:,:,2);
I2(:,:,2)=I1(:,:,1);
imshowpair(I1,I2, 'montage');

Now if I take your title literally, let's say you do want to add the three layers and display the result with a colormap, you can do:

A=a(:,:,1)+a(:,:,2)+a(:,:,3)
imagesc(A); axis image; 
colorbar;

Results: