Recently, I needed to change 210 image filenames to be lowercase. I needed a quick way to do this other than one-by-one. Found this handy little script.
Open terminal, navigate to the directory with your images and paste this in the terminal window:
for f in *; do mv "$f" "$f.tmp"; mv "$f.tmp" "`echo $f | tr "[:upper:]" "[:lower:]"`"; done
Thanks to this solution on Stack Overflow – http://stackoverflow.com/questions/7787029/how-do-i-rename-all-files-to-lowercase