This is not the first time I’ve noticed difficulty matching highlights and shadows but it’s more apparent when I’m working from my monitor. Monitors use an additive colour method but I paint from a printed image; both paint and print are subtractive. I refer back and forth from the print to my monitor so the difference tends to cancel out a little. I don’t usually work directly from the monitor because some colours are impossible to replicate and the result is a little disheartening. I refer to the monitor but then use a printout when I’m painting. I know that some colours are better on the monitor than they are on the print and I try to compensate, so the painting looks better than the print when I’m done; which feels good.
I have access to a photo printer or I could use the photographic settings on my cheap little printer but why bother when I can occasionally look at the monitor. The time it actually takes me to get to painting is enough that I can no longer remember the exact colours but I do try and sometimes get it fairly close. If I had a Mantis Shrimps eyes then maybe I could but it’s not possible with human eyesight.
The result of all of this is the monitor image does not match the painting. In particular the contrast is off significantly. As a result I’m looking at the painting and seeing much less contrast. I tend to ignore the actual colours but they are also significantly off as a result of the different methods of rendering colour. One method I’ve found to increase the apparent contrast in the painting was developed (I believe) during the renaissance. This method is similar to Unsharp Masking in Photoshop. The bright areas increase in brightness as they approach the dark areas and the same treatment is applied to the dark areas. This is usually a dark line in the dark areas and a light line in the bright areas applied just at the separation. Since I want the areas to appear sharper I switch to a smaller brush and add thin dark and light lines to various areas of the image. This seems to make the image ‘POP’ and increases the reality illusion.
I’ve included a detail of the painting I’m working on to show where I’ve used this technique. Some paintings don’t require it.