CROP(FILENAME,APPEND,MARGIN) is the full calling form. APPEND and MARGIN are optional inputs.
CROP('filename.ext') crops the image in the file and saves it using the original filename, overwriting the old image. The extension (ext) can be anything IMREAD supports.
CROP(directory) crops all images in a directory.
If APPEND is 1, CROP saves the cropped image as 'filename_crop.ext' in the same directory as the original.
MARGIN sets the margin width in pixels (default is 10).
Requirements: your FIND must allow the 'last' option (version 7+?)