How to substract an image?

rgbImage = imread(fullFileName);

I want to only get the top 20% of the image. How can I do it?

For example, for this image

I only want to get

Thanks!

Answer 1

[Guillaume]

This is simple matrix indexing:

croppedimage = rgbimage(1:round(size(rgbimage, 1)*0.2), :, :)

Alternatively, use imcrop