https://twitter.com/spleenal/status/1324389384989364224 @spleenal maybe overkill or not usable for you but you could do it easily with some shadertoy code? eg https://www.shadertoy.com/view/3d3Bz7 takes a video feed and quads it and is easily to tweak to 3x3 or whatevers. ( the *2.0 on line 7 )

Might even run on your phone :)