Image names appear in the Title Bar of the image window. You can change the image name by clicking on the image to make it the active or front image, then clicking on the Name! button. This presents a dialog to change the name. You can change the name to whatever you want, but it is a good idea to keep the names unique and relatively short.
Besides using the Name! button, image names can be changed also while saving to a file. The dialog will ask you for a file name, giving the current image name as the default.
Image names can be long and tedious to type. To cut and paste an image name