Tux Paint - Tux Paint is a free, award-winning drawing program for children ages 3 to 12 (for example, preschool and K-6).
CODIJY Pro Photo Colorization - Add colors to black & white photos and recolor images with surprizing ease!
Lil' Picasso - Lil Picasso is a coloring and creativity package for children.
DeOldify - Open-source deep learning project for colorizing and restoring old images
Painty - Kid, if you have a dream to paint the best picture in the whole world, this is the place to start...
Palettte App - Create, analyze and edit smooth color palettes