can iStopMotion 3 edit a frame with gimp?

I see how to edit with Preview. Editing with Preview shows a filename like 0x79e78760_1135.png but entering that filename in OS X Spotlight doesn’t find anything.

How can I edit individual frames with Gimp?

You have to setup GIMP (or e.g. Adobe PhotoShop) as your Graphical Helper Application (“Preview” is just the default). To do so: open the iStopMotion Preferences, select the “Helpers” tab and choose your GIMP app in the “Image Editor” option.

Now you can open frames directly from iStopMotion: select the frame in question in the timeline and right-click on it to get the context menu for this frame. Select the “Edit in GIMP” menu item.

GIMP will start and open the frame. Do your editing. When you are finished with your editing please use the “Overwrite istopmotion_xxxxxx.png” menu item in the files menu, otherwise iStopMotion will miss your changes. After that close your image without saving!

Now go back to iStopMotion. iStopMotion will see the changes you made and automatically import your image back into the project.