I want a desktop entry like MimeType=image/ETC to create a context menu action in Dolphin (File Manager in Linux Mint KDE) that would appear only for images.To the question Is there a generic mime-type for all image files the answer seems to be no.On the other hand, for my limited purpose of editing a .desktop file in Linux Mint KDE to create an 'Action' context-menu entry in Dolphin File Manager that would be shown only for image files, there is a solution that was indicated in a comment to the linked question. I am creating this question to make that solution available here.
MimeType Desktop entry for all image files
images;mime types
There are indications, that the entry MimeType=image/* would do the trick:[Desktop Entry]Name=ConvertExec=convert.shMimeType=image/*;