Heavy-duty image processing is not what web (i.e. http) was designed for. But that's not to say it couldn't be done. You could show a checkbox by each image, and somewhere on the page (probably the top) have a menu of functions to be applied to the selected images. There could be a couple text inputs as well, for those functions which require parameters. File renaming, if necessary, and such things, could be "smart", done by the server program (your cgi) with little or no input from the user.