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YUV footage, chroma shift in Photoshop

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Rob Hornsby
YUV footage, chroma shift in Photoshop
on Oct 11, 2012 at 3:00:29 pm

Hello,

I'm getting a chroma shift when round-tripping footage between Final Cut 7 and Photoshop CS5. My source footage is Uncompressed 8-bit (YUV colour space) and when I import it into Photoshop, it shifts the colour. (I assume because of Photoshop being RGB). Is there a way to prevent this from happening? Is there a Color Settings setting that would fix this, or any codec I can transcode to?

Thanks,
Rob


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Jonathan Ziegler
Re: YUV footage, chroma shift in Photoshop
on Oct 12, 2012 at 4:28:15 pm

I see you're running a Mac so I'll see if I can tackle this:

1) re-calibrate your monitor in the OSX Display Preferences - I re-do this every month or so and more often during heavy use. Have a color profile for lights on/off, daylight, cloudy day, etc. The differences are subtle, but its worth it. Remember: Macs use Gamma 1.8 and PCs use 2.2.
2) Launch Photoshop and go to Edit >> Color Settings. Under Color Management Policies, make sure "Preserve Embedded Profiles" is selected and under Working Spaces/RGB, to match FCP7, pick the one for your computer monitor you just calibrated. Incidentally, you can choose a wide-gamut RGB, like Adobe 1998, here, too, but I think you'd be better off with your monitor's profile for more precise matching.
3) in FCP, go to your Sequence Settings (Command-Zero) and choose to render in YUV.
4) do a quick test of your footage: a small test render of a short bit of footage in FCP and view it in Quicktime side by side with the original footage. FCP is notorious for having wonky brightness for H.264 footage (ie: DSLRs and consumer camcorders using AVCHD). It has something to do with the file format trying to auto-correct to the correct gamut and failing. I could be way off on the reasons and I'm open to correction on that.

Finally, I'm not exactly sure how PS handles video footage. I'm assuming it treats it like a series of raster images like JPEGs and uses the current RGB color space. If none of the above works, try converting to a MotionJPEG or PhotoJPEG (A, I think) at no more than 90% (anything higher than 90% overtaxes the codec and you get massive file sizes - I use 85% when submitting stock footage).

If none of this works, please provide specifics: footage format, what it's shot on, any conversions via Compressor, AE, or MPEG Streamclip, etc. These are what I would do and hopefully someone else has more info.

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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Rob Hornsby
Re: YUV footage, chroma shift in Photoshop
on Oct 15, 2012 at 6:43:43 pm

Thanks Jonathan,

My footage is Uncompressed 8-bit YUV codec QT's straight from an animation house (footage is not live action, but an animated show).
I'm not as concerned about my Mac monitor as the colour shift is evident on a calibrated external client monitor that we have. I think we've found a solution though.

I'm now exporting the shots from FCP as their native Uncompressed 8-bit, then opening them in PS and adding a Levels input adjustment of 16 and 235.

I then make my fixes and export the QT from Photoshop as a None compressor, and import into FCP.

In FCP, I add a Gamma correction of 0.82.
This procedure seems to negate the colour shift. (except in the reds a little bit)

A bit of a pain but it seems to work

Thanks for the suggestions Jonathan!
Rob


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Jonathan Ziegler
Re: YUV footage, chroma shift in Photoshop
on Oct 15, 2012 at 7:46:07 pm

Egads, sounds like a LOT of work, but if it works, I can't argue. ;)

I didn't even think to ask, but have you tried calibrating the external monitor? Also, can you use Apple's Color? Color can be a royal pain for fine tuning without a control deck, but I've done some good stuff with it. Also, be careful with Photoshop - despite their claims, Photoshop doesn't have the best color tools - see if you can get the color profile your footage's source company uses OR get a color profile from the camera manufacturer. Ask them to use a flat shooting profile before delivering footage or single sequential frames. The Cinestyle color profile, for example, can add a couple stops to a "normal" shooting profile. The footage lacks contrast and saturation, but its designed so you can bring these back in post to make color matching easier. Also, if they shoot a color chart made for their camera(s), you can fine tune colors like you wouldn't believe.

Either way, glad I could help! :)

Jonathan Ziegler
http://www.electrictiger.com/
520-360-8293


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