This page only refers the Geeqie thumbnail caching mechanism, the shared thumbnail cache mechanism is described in Thumbnail Standards .
Thumbnails are stored in PNG image format. The thumbnail name is the name of the source image with “.png” appended.
The modification time (mtime) of the thumbnail is set to match the source file. Thumbnails are regenerated when the timestamps of the thumbnail and source file do not match.
Thumbnails are stored in a location specified in Thumbnail Preferences .
The directory structure of the thumbnail cache duplicates that of the location of the source files.
Geeqie allows the following sizes for thumbnails:
24x24, 32x32, 48x48, 64x64, 96x72, 96x96, 129x96, 128x128, 160x120, 160x160, 192x144, 192x192, 256x192, 256x256
The thumbnail is scaled to fit within the preferred size maintaining the aspect ratio. Thumbnails are not cached for images that are equal to or smaller than the preferred thumbnail size.
When a cached thumbnail's width and height do not match the preferred size, the thumbnail is regenerated.