That picture has more resolution than 64x48.
To get a mask for the green encircled regions in your starting image, you can do
[rows, columns, numberOfColorChannels] = size(rgbImage)
[r, g, b] = imsplit(rgbImage);
greenMask = r == 0 & g == 255 & b == 0;
% Fill to make solid
greenMask = imfill(greenMask, 'holes');
% Get mean values inside mask
meanR = mean(r(greenMask))
meanG = mean(g(greenMask))
meanB = mean(b(greenMask))
% Get mean values outside mask
meanRout = mean(r(~greenMask))
meanGout = mean(g(~greenMask))
meanBout = mean(b(~greenMask))
We don't know what to do next because what you said you want to do is so vague. Like exactly what does " take all that matrix value from that area out" mean? Do you want to crop the bounding box out to a new image? Do you want the mean R, G, and B in the regions? Do you want to mask the original image, blackening inside the green outlines? Do you want to measure areas or perimeters? Something else? I have no idea.
Please read
and clarify your request.
