Cropping area of interest

I want to analyze cells that I express both green and red on apical and basal membrane. Therefore, I try to load a red-green-blue merged image, crop the area of interest based on green and red, then split into three channels by using cropped area for subsequent analysis. Could you help me how to do it?
Thanks. I attach my image for your information.


You could define the region of interest (ROI) by either (a) using IdentifyObjectManually to define the ROI by hand, or (b) adding the red and green channels followed by IdentifyPrimaryObjects to automatically define the ROI. This ROI can be used as a mask by MaskImage for the red, green and blue channels; the individual channels can be obtained by the ColorToGray module.