Better heuristic to detect scene changes

[kemenaran]

Currently the heuristic to detect a scene change is to use a custom perceptual hash, that tries to detect when a large portion of the image changed.

Even after many fine tuning, this perceptual hash is not very good: it tends to have many false positives (changing a scene when the scene is actually the same) and false negatives (not changing a scene when it did actually change).

I guess this is, despite by best efforts, the function is still too sensitive to scrolling (which makes a large part of games).

Ideas for improvements:

• Try to find a perceptual hash less sensitive to scrolling (maybe like the sum of all luminance, instead of working per neighbouring blocks?)
• Or just change the scene when the screen goes all black or all white (because most games will fade to black or white when changing a scene anyway).