Recent discovery -- maybe everyone else already knows this trick

[jsachs]

I recently stumbled across a way to bring out colors in washed out highlights in images, namely to darken them using the HSL color space. While I always realized lightening images in HSL tending to wash them out, it didn't register that darkening them does the opposite. For the next release, I have updated Transformations.pdf and Curves and Histograms with examples.

Darkening HIghlights.jpg (137.94 KiB) Viewed 4649 times

[pierrelabreche]

Very interesting !

[Bob Walker]

Yes! Yes! Way way a long time ago, before the three-zone adjustment transform was invented, there was a recipe someone (den?) posted for manually doing that, involving making three masks (shadows, midtones, highlights) and then using the brightness curve to manipulate those brightness zones to taste. I do bet it was one of den's magic tricks.

For shadows, we would lighten in HSV mode, midtones in HSV, but darken highlights in HSL, producing what Jonathan just reminded us of. It works like magic. Does the three-zone adjustment use HSL for highlights? If not, maybe a good idea.

I used to follow that recipe so often I could almost do it in my sleep. Now I am old fat and lazy, and the three-zone works good enough. But I will darken highlights in HSL still, for those images that demand it.

Thanks for the reminder!

Bob W

[Charles2]

For comparison, this is the result of using Raw Therapee's Chromaticity-by-Lightness curve to raise chromaticity near the high end, followed by its Lab-L curve to darken the high end. (Obviously, I worked on the Original Image and left the label. I had RT output an sRGB image.)

HSLmodRT-b_crop.jpg (39.94 KiB) Viewed 4641 times

[jsachs]

Bob,

Just checked and I was not using HSL to adjust highlights in 2- and 3-zone transformations. For the next release, you can choose which to use via the Settings menu -- old scripts default to HSV for compatibility, but the default is HSL for new transformations.

[Bob Walker]

Super!