ParaPara
ParaPara is a free and open source, lightweight image viewer with three display modes: single, spread, and continuous
YOGA Image Optimizer
YOGA Image Optimizer is a free and open source graphical tool for converting and optimizing images in JPEG, PNG and WebP format
Colorway
Colorway is a free and open source program for generate color pairings
Emulsion
Emulsion is a free and open source simple program for storing and editing palettes
Image Roll
Image Roll is a free and open source, simple and fast image viewer with basic image manipulation tools
Image Optimizer
Image Optimizer is a free and open source simple program for compressing images without loss of quality using JpegOptim and OptiPNG
Koko
Koko is a free and open source image viewer designed for desktop and touch devices
gThumb
gThumb is a free and open source program for viewing and organizing images in Linux
CoreImage
CoreImage is a free and open source, lightweight and easy to use image viewer for Linux
Color Palette
Color Palette – free and open source tool for viewing the GNOME color palette