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is prores meant for online format? gamma issue again
Hi guys,
I’m a little stuck with a job and interested what you actually think.
One of my client has shot his movie with Panasonic P2 AG-HVX200 in DVCPRO HD (1920x1080i, 25p). He converted all his stuff to ProRes (HQ) with Apple Compressor.
He edited his movie, did some primary color correction in FCP and exported some shots for me in ProRes.I have to do some simple retouch on these shots in Nuke. The problem is gamma as always. Nuke understands QT ProRes gamma, but when it’s about to output the final result, the QT codec fails and the final output is a little brighter than the original shot I got. (he needs the retouched shots in ProRes)
I spent many time to find out a solution, tried many tricks, but the difference is always there. After a while I realized that since the problem roots in how macs understands the same video data, I can’t really do much.
(more on this here: https://support.apple.com/kb/HT2912 and https://provideocoali…cktime_movies/ unfortunately QT Gamma Stripper doesn’t work for ProRes)But still I believe there must be some workaround for this. It can’t be that many workflows are built on ProRes (like Arri Alexa) and this problem isn’t solved.
I’m a vfx artist, not an editor. I don’t know fcp at all. But I’d like to find a solution. Please tell me guys what would you do.
Is it possible to mix file formats on fcp’s timeline? Or should I work on the original P2 files? Any ideas?
Many thanks,
Gyuri
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5 Replies
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If you render to any other codec, is there a shift?
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[Gyuri Szlamka] “I have to do some simple retouch on these shots in Nuke. The problem is gamma as always. Nuke understands QT ProRes gamma, but when it’s about to output the final result, the QT codec fails and the final output is a little brighter than the original shot I got. (he needs the retouched shots in ProRes)”
When you say the “QT codec fails” what exactly do you mean? Are you rendering out to ProRes from Nuke, or some other format? Is your write node set to the Rec. 709 color space?
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
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Thanks for all your input.
All the tests I describe below is just I/O + format conversion in Nuke. I didn’t do anything else with the image.
@Jeremy: I haven’t tried it on mac, on PC I made jpeg and tga seq. I exported tga seq with rec709 colorspace. QT player showed it darker, but when I loaded it back to Nuke, there was no difference from the original.
@Walter: Now everything on mac: I import the original file (ProRes HQ 422)to Nuke with rec709 colorspace and export a test.mov with exactly the same settings (ProRes HQ 422 and rec709 colorspace). I import the test.mov to Nuke again and there is no difference between the original and test.mov. (OK some recoding artifact, but only visible at maximum gamma value)
In QuickTime player test.mov is definitely brighter that the original.I guess QT player sees the two (almost identical) video differently and I can’t do anything with it.
Thanks again.
Gyuri
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Oh, you are comparing in QuickTime?
What OS are you on?
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Gyuri,
These tests are only really meaningful if you send your output back to the editor and he/she A/B’s them with the originals in FCP on a broadcast monitor, through proper hardware.
Comparing stuff in Quicktime can sometimes be helpful, but can also be misleading unfortunately.
We had similar issues with ProRes VFX work at the shop I’m currently at. However, I think it was a YUV>RGB>YUV color shift issue, as opposed to a gamma problem (the Nuke artist was rending to the Animation Codec originally). We switched the VFX renders to 10 Bit Uncompressed and the problem went away. You might want to give that a shot.
Matt Lyon
Editor
Toronto
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