When I begin a painting using one of my photos in a layer, I think of it as a highly detailed finished but not dry oil painting. I want to be able to scrape away with a palette knife and add paint strokes to the "wet" photo painting. That is how I can go beyond the limits of naturalistic and photo-realistic paintings. The feature would essentially change the photo into a thick paint layer of many colors which I could change with brushes and palette knives. Maybe this feature exists, but I am just not aware of it.
I_think_it exists (at least in Painter 2021 and newer)....here are the steps.
1. Open the Photo. If it is a JPG, nor further action is needed.
2. If it is a PNG, RIF, PSD etc....go Menu > Layers > Drop All
3. Now you can go Meny > Layers > Lift Canvas to Thick Paint layer
4. A dialog pops up with a lot of options...I like to set "Thickness source" to "Image Luminance" (which means light/dark areas of the photo will determine how thick the paint will be)...I also like to increase thickness a bit
5. Select your favorite thick paint knife and go!
Note that this can also be used with cloning, so if you're interested in those additional steps let me know....
I thought the process I was looking for was reasonable within Painter 21, but I wasn’t able to find it. Thank you so much for your solution. I hope to use it soon. I’ll let you know about the results.