GIMP is a free program for such photo retouching, image composition and image authoring. Essentially it's the closest thing to Photoshop you can get for free.
Fast and compact image viewer/converter trying to be simple for beginners and powerful for professionals. Many supported file formats and features. Features included: multi-language support, Thumbnail option, Painting, slideshow, toolbar skins, fast directory browsing, batch...
Glimpse is an open source image editor based on the GNU Image Manipulation Program. The goal is to experiment with new ideas and expand the use of free software.Discontinued
The Glimpse editor has been discontinuedSource: https://glimpse-editor.org/posts/a-project-on-hiatus/
Seashore is an open source image editor for Mac OS. It features gradients, textures and anti-aliasing for both text and brush strokes. It supports multiple layers and alpha channel editing. It is based around the GIMPs technology and uses the same native file format.
XGimp is an adaptation for iPhone and iPad of the app GIMP (GNU Image Manipulation), which is a freely distributed program for tasks as photo retouching, image composition and image authoringThis app doesn't have any features at the moment.
A new image viewer that has nice features like identifying and generating colors from image, changing colors of image with color adjustment and color matrix tools, crop & split image for Instagram, TIF/GIF Animated extractor, batch functions.Discontinued
The last update is from 2019.
RealWorld Photos is an free portable photo editor for Windows. Retouch photographs and batch process images in an easy-to-use editor. Perform lossless retouching, watermarking and other operations on .jpg images.
WidsMob Retoucher is an excellent photo retouching program, which is able to reduce image noise, portrait retoucher, film pack, adjust effects, fish eye effects, vignetting and more other features to photos with ease.
Photo Toolbox is an utility software that allows you to edit, retouch and fix your digital photo. It combines many easy to use and very powerful features which can make your photo much better than before.This app doesn't have any features at the moment.