To add color to.
(Canadian spelling, acceptable) To convert black and white media to color by digital post production (as is often done in digital photography and in video special effects).
To colour the roots of hair to match hair previously coloured.
To modify a flint tool by making secondary flaking along the cutting edge.
To improve something (especially a photograph), by adding or correcting details, or by removing flaws.
The act of retouching.