Dear Alexey,
thanks for your reply. That worked so far. So I made some tests and got a small success detecting a simple black/white colored image using this command:
img = PhotoScan.app.document.activeChunk.cameras[0].image()
PhotoScan.utils.createDifferenceMask(img, (0,0,0), 50, True).save(r"d:/tmp/test_mask.png")
The RGB tuple represents black color (0,0,0). So far so good.
Then i tried a real image (see attachment). I picked up different colors (e.g. paint) from the sky in the image and tried the same command as above but without success. I also tried to use 100 tolerance, but no success. Here are colors I tried out:
137,230,216
185,214,205
231,247,255
The result was always an empty (white) mask image.
What did I do wrong? Do I need to use another color picker, other color format?