retouch

Short definition from Wiktionary

Verb

1. 1
   To improve something (especially a photograph), by adding or correcting details, or by removing flaws.
2. 2
   To colour the roots of hair to match hair previously coloured.
3. 3
   To modify a flint tool by making secondary flaking along the cutting edge.

Noun

1. 1
   The act of retouching.