O Gimp de fato tem um modo em lote :
GIMP comes with a so-called batch mode that allows you to do image processing from the command line. It also makes it easy to apply the same set of operations to a number of images. We have got a lot of questions on the mailing-lists on how to use the batch mode and this small page tries to explain the basics to you.
(A criação de scripts é feita na linguagem Lisp extremamente assustadora, se isso for um turn-off, no entanto.)
Então, o Photoshop :
The Batch command runs an action on a folder of files. If you have a digital camera or a scanner with a document feeder, you can also import and process multiple images with a single action. Your scanner or digital camera may need an acquire plug-in module that supports actions.