Re: The color of QuickTime 5 (Eric Blanpied)
Re: The color of QuickTime 5 (Eric Blanpied)
- Subject: Re: The color of QuickTime 5 (Eric Blanpied)
- From: Don Hutcheson <email@hidden>
- Date: Fri, 05 Oct 2001 02:03:27 -0400
Eric,
Nice, succinct explanation. You didn't blow it.
About the only processing that might be applied on-the-fly during QT
playback without serious speed bumps would be three 1-D LUTs, perhaps
applied between QT and the display or in the current Apple Video LUTs. Could
these be loaded once and then just sit there while the video played through
them? Are the Apple VLUTs fast enough to pump real-time video through
without stuttering? If the LUTs are created as full 8 bit-in, 8 bit-out (256
entries each times three) there would be no interpolation required, just a
straight index in, value out operation for each of three discrete RGB values
per pixel. Without doing the math it seems feasible at today's processor
speeds.
At playtime, QT would extract the gamma and white point from a profile
(attached to the clip or specified independently as a QT default) and use
those data to build the LUTs. Any 3-D LUT and/or matrix in the profile would
probably have to be skipped due to the huge processing burden, meaning
color-dependent functions like saturation and hue correction would not be
applied. But gamma and white point are usually the most significant part of
any profile and for video I'd say honoring the intended Gamma would be a
great first step towards QT color management.
Don
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Don Hutcheson
Hutcheson Consulting
(Color Management Solutions)
11 Turnburry Rd
Washington, NJ 07882
Phone: (908) 689 7403
Fax: (908) 689 5305
Mobile: (908) 500 0341
email@hidden
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