On Mar 31, 2012, at 2:57 PM, Dan McCabe wrote:
> Anyone know how auto-color balance works in the CC? Saw an Avid CC
correction demo this week and it was never really explained.
I say:
I can tell you how auto balance works in general. A color imbalance
may exist in scenes that contain unequal RGB gains and ped levels.
IOW, 'white' isn't really neutral white and 'black' may contain a bias
towards one or more colors). These imbalances are usually caused by
the lack of proper camera white- and black-balance when the scene was
shot. Auto-balance compares the relative levels of R,G, and B in the
overall scene and adjusts the gain and ped of the 3 color channels in
order to minimize any color bias at the white and black levels. Since
auto-balance cannot take into account any errors in gamma (it cannot
measure gamma nor many other parameters), the use of auto balance is
fairly crude and limited. All it sees is the relative peak and
pedestal differences between red, green, and blue. Using that
information, auto-balance then adjusts peak and ped levels of the 3
color channels in order to minimize measurable color bias in the
blacks and whites. Its use is not intended to replace a serious
careful color grading done by an experienced specialist.
Dennis Degan, Video Editor-Consultant-Knowledge Bank
NBC Today Show, New York
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