Blender
www.blender.org/
Blender is a professional free and open-source 3D computer graphics software product used for creating animated films, visual effects, art, 3D printed models, interactive 3D applications and video games. Blender’s features include 3D modeling, UV unwrapping, texturing,raster graphics editing, rigging and skinning, fluid and smoke simulation, particle simulation, soft body simulation, sculpting, animating,match moving, camera tracking, rendering, video editing and compositing. Alongside the modeling features it also has an integratedgame engine
IrfanView
www.irfanview.com/
IrfanView is a freeware/shareware image viewer for Microsoft Windows that can view, edit, and convert image files and play video/audio files. It is noted for its small size, speed, ease of use, and ability to handle a wide variety of graphic file formats, and has some image creation and painting capabilities. The software was first released in 1996. IrfanView is free for non-commercial use; commercial use requires paid registration.
The Gimp
www.gimp.org/
GIMP is an acronym for GNU Image Manipulation Program. It is a freely distributed program for such tasks as photo retouching, image composition and image authoring.
It has many capabilities. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, an image format converter, etc.
GIMP is expandable and extensible. It is designed to be augmented with plug-ins and extensions to do just about anything. The advanced scripting interface allows everything from the simplest task to the most complex image manipulation procedures to be easily scripted.
VectorMagic
vectormagic.com/home
Automatically convert bitmap images likeJPEGs, GIFs and PNGs to the crisp, clean,scalable vector art of EPS, SVG, and PDF with the world’s best auto-tracing software.