Ristretto
Ristretto is an image viewer for the Xfce desktop environment. Free and open source program
KGeoTag
KGeoTag is a photo geotagging program. Free and open source
CorePaint
CorePaint is a simple bitmap painting program to create very simple graphics. Free and open source program
Pix
Pix is an image manager and image viewer. Free and open source program
vipsdisp
vipsdisp is a free and open source program for viewing very large images
XnRetro
XnRetro is a free and open source, multiplatform program for creating images with various effects
XnSketch
XnSketch is a free and open source program for turning photos into cartoon or sketch images
Oh My SVG
Oh My SVG is a free and open source software for convert unoptimize SVG files into smaller versions
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