Colorizing shades of grey

[timtak]

I have a tough time adding colour to black, white, and shades of grey. If there is colour there already then I can use the colourful-doughnut icon "Hue and Saturation" tool's "colorize" to change the colour. but it is tricky to keep tones and add colour to near-whites, greys and near blacks.

If something were completely black or white, I could isolate it and use the bucket fill tool but when I want to maintain tones but colourise I am stumped.

The guy attached (one of my seminar students. I have removed his face to maintain his privacy) was wearing white grey and black. I wanted him to be more colourful. It took me a lot of work to add colour to his "white" (in fact light grey in the image) jacket by playing around with the brightness, decreasing the gamma and then using the "Hue and Saturation" "colorize" tool repeatedly I think.

corrected a mistake or two

I gave up on his trousers and shirt.

I guess that there must be a lot of people colourising old black and white photos.