How Can we extract the green channel matrix alone from colour image? Is there any formula apart from matlab extraction

How Can we extract the green channel matrix alone from colour image

Answer 1

[Guillaume]

greenchannel = rgbimage(:, :, 2);

The first page of an rgb image is the red channel, the 2nd is the green channel and the 3rd is the blue channel, hence the name rgb.

Answer 2

[Walter Roberson]

If you need to do it by mathematical formula, then you can use a Projection Matrix

[r, c, p] = size(YourRGBArray);
GreenPlane = reshape(reshape(YourRGBArray,[], 3) * [0; 1; 0], r, c);

I do not recommend this for practical use; matrix indexing is faster and clearer.