[FYI] Do this…

Start with directories if you are changing them for the web server first, this will change files too:

$> find images -type d -exec chmod 755 {} +

Then run it again to change files, with the different switch:

$> find images -type f -exec chmod 644 {} +

I recommend adding a recursive (-R) switch along with a verbose output (-v):

$> find images -type f -exec chmod -Rv 644 {} +

You may need to use super permissions to action this. Be warned, this can lock you out.