th in pixels (default is 10).
 
    Changes since version 1:
        1. Now accepts directories as input.
        2. Improved input checks and comments.
        3. Handles transparency in .png files.
        4. Just prior to saving version 1, I added the APPEND option.
 
    Example:
        <a href="crop.html">crop</a>('C:\MATLAB7\toolbox\matlab\demos\html\cruller_01.png',1)
 
    See also: IMREAD, IMWRITE
    See crop_license.m for the license details.
    Written by Andy Bliss Sept 8th, 2006. Revised May