The darkest possible black, not the light black. Darkest black is when watching a 4:3 in 16:9 full screen (4:3 video in the center). At each side is very dark black, then light black between the dark black and picture. Its the darkest black thats needed.
Also i notice this may help more than just 4:3. How many times i have watched those retail dvd's that put 4:3 even 16:9 in a widescreen frame (letterbox cutout) and leave light black where there should be dark black. I can see an extremly busy few years if a mask is added to the cropper. First doing all old tv caps, then doing all those ugly light black dvd's to dark black.
Mask would be good if can select top, bottom, left and right. That way it covers everything. And helps users to keep videos to same A/R. I normaly only use cropper for stripping away light black. Occasionaly for A/R correction. And another software that can resize, crop and resize again and again if needed. Of course an upscale then a resize to correct A/R is normal.
Cropper to remember its own screen position for each time we the cropper.
