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Photo jpeg compression

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Chris Walker
Photo jpeg compression
on Sep 12, 2009 at 3:11:10 am

Hello,

I've been having problems with a color/luminance shift when exporting to the photo jpeg codec out of an avid timeline. The footage looks great in the avid, but when I export using photo jpeg it becomes a little washed out and looses some saturation. I am encoding at best quality, have no filters on at export, using a Mac with QT7. I know there is a known gamma shift with H.264, so are there any known problems with the photo jpeg codec and any workarounds to fix it? I have to supply footage using this codec but want it to look right. Sorry if this is a stupid question, but I'm a bit of a newbie. Any help will be greatly appreciated. Thanks.


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Daniel Low
Re: Photo jpeg compression
on Sep 12, 2009 at 9:58:10 am

[Chris Walker] "I am encoding at best quality"

How far to the right is the quality slider in the PhotoJPEG compressions setting options?



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Chris Walker
Re: Photo jpeg compression
on Sep 13, 2009 at 12:55:26 am

How far to the right is the quality slider in the PhotoJPEG compressions setting options?

It's at 100%. But I've also tried it at 90% and the same thing happens (although the file size is quite a bit lower).

Has anyone heard of this happening with this codec? I'm at a bit of a loss as to how to fix it.



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Daniel Low
Re: Photo jpeg compression
on Sep 13, 2009 at 7:19:50 am

What format of video are you editing? It may well be that what you are seeing is the effects of colourspace conversion from the timeline of 4:x:x to the 4:4:4 of the PhotoJPEG codec.

__________________________________________________________________
"There's no chance that the iPhone is going to get any significant market share. No chance."

Steve Ballmer To USA Today


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Chris Walker
Re: Photo jpeg compression
on Sep 14, 2009 at 9:49:56 am

The footage is all 4:2:2. So if that's the problem, is it possible to fix it?

I also did a test by dropping the quality to 75%, because I read that the codec drops to a 4:2:2 color space at 75%, but it still has the same shift. Does this mean that it will always happen with this codec?


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