View Window - Image | Count Unique Colors...                    U



This option counts the number of colors in an image.


For images stored as 8 bits per pixel or fewer, it is very fast; but for 24-bit images, it may take a while (and temporarily use up to 2MB of memory). If there is insufficient memory to count the actual colors in an image, ThumbsPlus will ask if you want an estimate instead.


Counting the number of colors in 48-bit images is not always possible due to memory considerations (you may receive an "out of memory" error).