FreeImage is a library project for developers who would like to support popular graphics image formats (PNG, JPEG, TIFF, BMP and others). Some highlights are: extremely simple in use, not limited to the local PC (unique FreeImageIO) and Plugin driven!
Display a simple graphical dialog box to add or edit Exif UserComment contained into images. Supports Unicode UTF-8 characters.
Originally developed as a plugin for Geeqie image viwer.
It requires Python GTK+ and exiv2 tool.