As I was processing the other day, trying to slightly darken an area that was just a tad too bright, I was reminded that the perceived luminosity is dependent on the luminosity values next to any given specific area. I have read about this in several books but never fully grasped the implications.
I had made a Curves adjustment layer targeting the area I found too bright thus creating an unbalance in the composition. An eye magnet of sorts. I painted with a low opacity white brush on the mask to reveal the adjustment. Toggling the adjustment layer on and off — as I always do — I noticed that the adjustment made it even worse. At first I couldn’t understand why, but then I realized that I had done a poor job with the mask, darkening the area surrounding the area the adjustment was intended, for actually increased the perceived luminosity for the very reason mentioned above. Refining the mask, only revealing the targeted area, gave me the result I was after.
Following the fact that perceived luminosity is dependent on the luminosity values in the adjacent area, you actually have two options making local adjustments. If to bright, you can either darken the problem area, or brighten the adjacent area. If two dark, you can brighten the area or lighten surrounding area. Or in some cases, a combination of the two approaches.
Incidentally, one of the reasons that I do the majority of my processing in Photoshop and why I find it so powerful is the ability to quickly evaluate my adjustment layers by toggling them on and off. Only by doing this can I see if I achieve my intended objective. Equally important is the ability to carefully adjust the opacity, in many cases as little as ten percent can be the difference between perfection and an improvement.
Illustration from my ‘Visions‘ portfolio.