ola,
4-2-2 or 4-1-1 reduces space in a great way, but if you need to make
manipulations that moves information from color to luminance the
method might be a rather bad idéa. Worse even, if you need to use
color-information for creating an alpha-channel (blue-screen/green- screen f.ex.) you might experience serious loss of quality.
sick of quality maniacs and of professors, hey man, we knew what you taught us.
ask yourself why many people work in YUV ( and i'm not defending it, i don't care )
sevy