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Kona 2 and Kona 3 Colorshift

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mobyzipper
Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 5:26:23 pm

we are currently running some tests, but when we capture an uncompressed quicktime using final cut and our kona cards, there is a color shift.
That same clip exported as an uncompressed quicktime through a flame has no color shift. can anyone explain?


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JeremyG
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 5:45:40 pm

Where do you see the color shift?


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mobyzipper
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 5:49:18 pm

mostly in the blues


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JeremyG
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 5:53:18 pm

Sorry, I should have been more specific. Do you see a color difference from the tape? Do you see a color difference in FCP? DO you see the difference after export? If it's after export, what codec are exporting to? What codec are you capturing to? Basically, give me your workflow and at what step in that workflow are you seeing the color shift?


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mobyzipper
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 6:15:04 pm

we encode mostly from digi (NTSC/PAL) or D5 (720/1080i/1080p) we capture uncompressed 8-bit. The frame ratere is always a little off. so we re-export with "None" compression at that formats correct framerate. When we play it back in quicktime after the export is when we notice the color shift. different from what is on the tape, and the uncompressed quicktime we exported from the flame. (the later two match)


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JeremyG
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 6:22:31 pm

That's because you are working with a YUV codec in FCP, then exporting to an RGB codec (none compression). There will be some color shifting happening in a situation like this. If you exported to 8 bit, you wouldn't see that. The reason you don't see it in flame, is because flame works in RGB, no?

What do you mean the frame rate is off? You aren't trusting Quicktime's judgement are you? If you are reading the frame rate off of QT Player it guesses wrong all the time.

Jeremy


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mobyzipper
Re: Kona 2 and Kona 3 Colorshift
on Mar 22, 2007 at 6:52:48 pm

gonna run some more tests


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David Battistella
Re: Kona 2 and Kona 3 Colorshift
on Mar 23, 2007 at 5:14:35 pm



Probably the best YUV to RGB codec, which retains nice color fidelity is the SHEER Video codec (look for my article on this in next months COW magazine) You will also like that it is one fifth the size of NONE, that it is cross platform and that it plugs in as a regular QT codec.

David


http://www.bitjazz.com

Peace and Love :)


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mobyzipper
Re: Kona 2 and Kona 3 Colorshift
on Mar 23, 2007 at 8:28:21 pm

OK Test Results......
We encoded the same clip as Uncompressed 8-bit, Uncompressed 10-bit.

Kona_8bit_Exported_10bit.mov
Kona_8bit_Exported_8bit.mov
Kona_8bit_Exported_None.mov
Kona_8bit_Original_FCP_Encode.mov
Kona_10bit_Exported_10bit.mov
Kona_10bit_Exported_8bit.mov
Kona_10bit_Exported_None.mov
Kona_10bit_Original_FCP_Encode.mov

All files were compared again the original Flame version.
All files had a color shift. Even NTSC Colorbars had a shift

Using another codec doesn't solve the problem when a client asks for an uncompressed quicktime. Does anybody know about the Kona cards yuv-rgb converion?


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gary adcock
Re: Kona 2 and Kona 3 Colorshift
on Mar 26, 2007 at 2:52:37 pm

this might explain a little

http://docs.info.apple.com/article.html?artnum=93794

when you are converting between formats QT assumes way too much, since most flame work I see is in Sequential Targa files you are converting between RGB and YUV color spaces.
you should never use QT to change between color spaces.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows


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