[Tig] fade ins, fade outs.
richard at filmlight.ltd.uk
Tue May 5 08:56:01 BST 2009
Is rec709 'clipped'?
In digital terms it is not more 'clipped' then conventional log RGBwhich
go from 0-1023. The difference is in how the colors reach the limit at
the top end. Film log RGB flattens off gracefully as you get to the
'toe' of the print stock exposure curve, so you can have highlights that
clip but still look pleasing. Video, on the other hand, has a luminance
curve that gets steeper and steeper until it whacks into the limit,
which can give you rend and yellow bands around your highlights as the
red, green. and blue channels saturate in turn.
This does not mean there is anything 'wrong' with video as such: it is
just a standard for processed image data. It was originally designed to
keep your color telly simple and cheap (simple and cheap when compared
to a 1950's computer, that is). On the other hand 'log' is a working
standard with the handy property that you can grade images up and down
and fetch data from the highlights or the shadows. To some extent you
can fetch a bit back from the beyond-legal video range when you edit,
but you still slam visually into the upper limit.
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