LibGuides: Free Software: Photo / Image

Image editing

GIMP
A free alternative to Photoshop. You can also find documentation and tutorials on this site. It looks like it has most, if not all of the features of Photoshop but Photoshop users might find the interface a little hard to use at first. A novice, though, might find it to be just fine since they don't know any better.
Paint.NET
(Windows only) A cross between MS Paint and Photoshop, Paint.NET is a free image and photo editing software. It features an intuitive and innovative user interface with support for layers, unlimited undo, special effects and a wide variety of useful and powerful tools. An active and growing online community provides friendly help, tutorials and plugins that add many more Photoshop-like features.
Paint.NET - online community
Paint.NET - tutorials
Paint.NET - plugins
PicMonkey
a web-based photo-editing tool that offers free basic editing options, and advanced editing with a paid membership
Ballpoint
This free, web-based tool allows you to create vector graphics. A simplified alternative to Illustrator

CloudConvert
free web-based tool that allows you to convert from a massive range of file types (videos, photos, audio, documents, etc.) to an equally wide range of formats

New Old Stock - vintage photos
Freerange Stock
Photos can be used for personal and commercial projects. Just required to sign up for a (free) membership
Stockvault
A photo-sharing site where photographers and designers can share their images for free. Images are free for personal and non-commercial use.
Burst
Photos on this site have a Creative Commons Zero license, meaning that they are completely royalty-free.

CameraSim
Created by photographer Jon Arnold, this free web tool allows users to simulate capturing photos with a DSLR camera. This tool can help users gain a visual understanding of basic camera settings.