Apps with 'Editing photos' feature
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.
The standard in professional image editing and compositing for creative design work.
Paint.net is a free and very capable image editing software for Windows. Great alternative to Photoshop for people that do not need all the stuff PS offers.
Professional image editing software for desktop and iPad.
darktable is a virtual lighttable and darkroom for photographers: it manages your digital negatives in a database and lets you view them through a zoomable lighttable.
Online photo editor, which can work with PSD, XCF and Sketch files (Photoshop, Gimp and Sketch App). Convert between PSD, XCF, JPG, PNG and many other formats. .
JPEGView is a lean, fast and highly configurable viewer/editor for JPEG, BMP, PNG, WEBP, TGA, GIF and TIFF images with a minimal GUI.
You can use the Photos app to view or edit photos and videos in your Pictures library and on OneDrive, and to import photos and videos.
A full-featured home-hosted Cloud Drive & Personal Assistant. Convert files, create archives, scan for viruses, perform OCR on images or documents, stream media, edit images and more! Compatible with HRC2 Apps!.
Photo editor and manipulator.
ProCam 4 offers unparalleled control and quality with DSLR-like camera functionality and full featured photo / video editing capabilities.
Moments is a complete album design package aimed for both professional and amateur photographers. Create beautifull album page layouts with a fast, easy to learn, clean, drag and drop interface.