Use this tag for questions related to the changing/combining of files containing pictures or other images. (Dumps of filesystems are often called images, but handling those is not called image-manipulation)
Image-manipulation, also called image-editing and photo-manipulation (although not restricted to photographic image files), is the changing of image files (TIFF, PNG, GIF, JPEG) using some tool. Changes can be interactive (e.g. with GIMP, or with non-interactive commandline programs (such as ImageMagick, or GIMP in batch mode).
image-manipulation is restricted to graphical images in a file, although a dump of a filesystem or partition is often called an image, handling such files is not considered image-manipulation