TextureLab
Material Maker
Substance Designer
PixaFlux
Filter Forge
Substance Alchemist
TextureWorks
TexGraph
kdiff3
Beyond Compare
WinMerge
Meld
Araxis Merge
DiffMerge
P4Merge
Devart Code Compare
TextureLab
kdiff3Material Maker - Cross-platform, procedural texture generation tool.
Beyond Compare - Beyond Compare allows you to compare files and folders.
Substance Designer - Substance Designer is a node-based non-destructive application for material authoring.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.
PixaFlux - PixaFlux is a node based image processing application.
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.