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Re: Core Video/ H.264 Color issues

Subject: Re: Core Video/ H.264 Color issues
From: Roger Howard <email@hidden>
Date: Sun, 9 Apr 2006 16:46:08 -0700
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On Apr 9, 2006, at 3:52 PM, Charles wrote:

This can change depending on OS platform, video hardware, and drivers.
I find it hard to believe that consistent color reproduction is so
difficult to achieve.
It's non-trivial, which is why it's impossible to achieve consistent color reproduction even with stills/photos. Heck, it's still not possible to make a PNG image match CSS colors in all modern browsers.

This is not an inherent problem with PNG or color management, this is due to bad implementations across different browsers. Quicktime has the luxury of being able to be consistent across browsers since it uses the same codebase - it's not like we're dealing with multiple vendor's implementing Quicktime support different.

If Apple wants to do gamma compensation on the fly during playback that's great, but tell us what to expect and make it work in a sensible way. For instance, *don't* assume 1.8 gamma on Macs and 2.2 on Windows; in fact if you can't discern the display gamma of the end user, pick a sensible default. Heck, let's be even smarter - assume the same gamma as you do for still images or HTML/CSS colors that aren't color managed; that way we can match colors consistently.

I reported on this apparent gamma issue when H.264 first shipped in Quicktime - I don't recall if I submitted a bug report or not, but I put up a page with sample files for testing this issue.

If this problem was consistent across all codecs then it would at least be comforting, sorta... but it's not. The same content in Photo JPEG, across the same machines, behaves differently from H.264. That points to inconsistent gamma (or color?) handling in Quicktime, depending on the codec. Not cool... _______________________________________________ Do not post admin requests to the list. They will be ignored. QuickTime-Users mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/quicktime-users/email@hidden

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