Rename 'jpg' to "JPG" dengan Paksa

find /path/to/images -name '*.JPG' -exec bash -c 'mv "$1" "${1/%.JPG/.jpg}"' -- {} \;

 use bash git in windows or linux to use thats script.

source: http://www.commandlinefu.com/commands/view/4471/rename-.jpg-to-.jpg-recursively