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Color shift from DaVinci to YouTube

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Mike Jenkins
Color shift from DaVinci to YouTube
on Jul 2, 2014 at 9:44:51 pm

Hi Forum,

I'm having issues maintaining consistency in my skintones across various exports. I use a well-calibrated monitor and on my system four different versions of the same color grade appear to have different skintones. The difference from DaVinci to FCP 7 is very slight, might even be from the screenshots more than the programs. So I'm not worried about that.

What I am worried about are two things:

1) Mainly, the massive shift in color from the h.264 export on my computer to what's shown on YouTube! It almost looks like I haven't done my job :(

2) There is also a color shift from FCP 7 to h.264 export. I expect a bit of a gamma shift, and it shows since my shadows are crushed a bit. What I didn't expect was the shift toward yellow in the girl's face. Is this because of the gamma shift, which seems to have brightened her face a bit as well?

I'm new to DaVinci and color grading in general so I would love some advice. If I need to pre-correct for these errors in my color grade I suppose I could take the YouTube still, make a grade to bring it back to my original, then apply that to my original?

Here's a picture to illustrate my dillema:

Thanks for the help!


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Erik Lindahl
Re: Color shift from DaVinci to YouTube
on Jul 3, 2014 at 6:44:56 am

The viewers aren't usually the best means of judging color accurately sadly.

A question:
How do you encode the final h.264?
How do you view your YouTube-clip?

Encoders and decoders of h.264 will vary, so will the software having or not having support for Color Profiles.


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Sascha Haber
Re: Color shift from DaVinci to YouTube
on Jul 3, 2014 at 7:13:37 am

Ok, first things first :

YOU have done your job !! And a good one :)

THEY havn't and they don't really care..
So what I do is , I skip YouTube completely and only vimeo where I am ok with the image quality.

Secondly, as Erik stated, try to help them...
They have a media encoder running 24/7 that crunches millions of cat videos and bad Karaoke and thats what it's for,
But you can use Adobe Media Encode, Compressor, Wondershare or any other EXTRENAL H264 cruncher you can get your hands on.
Personally, I only use DNxHD out from Resolve and then let Wondershare do the hack and slash.
Also because render times in Resolve a minimal and WS does multithreading and multitasking...so when i have to encode a bunch it does it on the fly in the Background.

The third and most important thing :

Try watching those clips on the YouTube App on an iPad,iPhone,Android on any cheapo Laptop....
Not you really need a beer and relax :)

A slice of color...

Resolve 10.1.4 - Smoke 2015
Colorist / VFX / Aerial footage nerd
http://vimeo.com/saschahaber


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Marc Wielage
Re: Color shift from DaVinci to YouTube
on Jul 3, 2014 at 9:55:42 am

Run color bars and a grayscale ramp through the entire process, and see what you get. I bet you could "pre-distort" the signal and get exactly the same thing back.

But in truth, consider the audience and what they're gonna watch YouTube on -- most likely laptops, tablets, and smartphones. It's going to look like crap anyway. All you can do is make sure it's not too crappy at the point it's uploaded, and check it on a few sRGB displays.

I only encode for YouTube using Compressor, and there's a million tutorials out there showing how to do it. And as others have said, there are better video, higher-res sites out there (like Vimeo) that are a little more faithful to the original in terms of color, gamma, and compression.

Note there are lots of known issues with gamma shifts and ProRes 422. 444 is actually more predictable, but it depends on where you're going with it.


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Michael Cinquin
Re: Color shift from DaVinci to YouTube
on Jul 3, 2014 at 10:48:07 am

in contrast to FCP, DaVinci completely ignores ColorSync icc profile chosen in System Preferences -> Monitor.

That is a good thing.

Those icc profiles are really for print, not for us working with native sRGB/rec709 monitors.

DaVinci viewer shows you an undistorted image, so it's up to your monitor to display it correctly. This means that if you output an image to a calibrated monitor via SDI, and look at the same image in the Viewer on a properly calibrated monitor, it should look the same. I measured this by feeding the DVI output of my monitor to a hardware scope in the past (I don't know if this works for all computers / software versions, I lost interest in this matter).

Then you can export quicktime Prores from daVinci. No gamma/primaries shift.
Then you can render this Prores to H264 with FFmpeg (for one). No gamma/primaries shift.
But then when you view the H264 in a web browser. ColorSync will strike in again (if you're on Mac and don't use a neutral profile), and you're going to see a gamma/primaries shift that is absent from the video.

I used to sell Color Profiles that prevented a gamma/primaries shift in Color (and allowed to see the same thing on Color UI and via the SDI output). These profiles are of course obsolete now that Color is obsolete, but the methods described on the page that allow you to judge ColorSync oddities are still perfectly valid

Using the icc profile "HD 709-A" on my macbook pro, I get perfectly consistent behaviour when looking at the video on daVinci SDI output, daVinci viewer, my web player and





Michael Cinquin

Charbon Studio, film finishing and DCP mastering
Post-production tools


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Joseph Owens
Re: Color shift from DaVinci to YouTube
on Jul 3, 2014 at 3:14:01 pm

[Michael Cinquin] "I lost interest in this matter)."
[Mike Jenkins] "I use a well-calibrated monitor and on my system four different versions of the same color grade appear to have different skintones. "

The ... somewhere between $6,000 and $72,000... question would be -- what do you characterize as a well-calibrated monitor and what would it be calibrated to or for? There is a lot of wobble room, and they are sadly, all valid in one way or another for something, just not everything.

Also you should be aware that there are values that can be generated in some colorspaces that cannot be reproduced in others -- some 10-bit colors just don't exist in 8-bit codecs... but as touched upon, different applications follow different rules as to whether internal profiles are observed or not for display. And that brings us back to ...doh. You know, the monitor and however the values are being mangled by the OS rules, by whatever whim the software engineers are on today that are obviously a better idea than the people who actually make up the standards.

jPo

"I always pass on free advice -- its never of any use to me" Oscar Wilde.


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Margus Voll
Re: Color shift from DaVinci to YouTube
on Jul 5, 2014 at 8:29:22 am

Also try Prores HQ and see what happens.

Both Youtube and Vimeo "eat it" despite the warnings it says you on the way.

--

Margus

http://iconstudios.eu
https://vimeo.com/iconstudioseu/videos

DaVinci 10, OSX 10.8.5
MacPro 5.1 2x2,93 24GB
GUI 4000 / GPU GTX 780
DL 4K
Eizo Color
Scope Box
Full Ligthspace CMS


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Joakim Ziegler
Re: Color shift from DaVinci to YouTube
on Jul 21, 2014 at 8:01:30 am

"some 10-bit colors just don't exist in 8-bit codecs"

While that's technically true, that's not something that will cause a color shift. If your codecs are working in the same color space (in most cases, Y'CbCr), they will cover the same gamut, just with different quantization. The "extra" colors in 10-bit exist between the 8-bit colors. So no, there's no color shift because of this.

--
Joakim Ziegler - Postproduction Supervisor


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Ron Fya
Re: Color shift from DaVinci to YouTube
on Jul 24, 2014 at 11:35:54 am
Last Edited By Ron Fya on Jul 24, 2014 at 11:40:12 am

Michael Cinquin,

I read your webpage about using the digital color meter (DCM)to judge about color sync oddities. Since you wrote it, the app has been updated and the options in its menu have changed. Can you help me understand the current version ?

You can view values as decimal, hexadecimal or percentage. That is fine with me.

But when choosing what is measured, you can choose between the following:
- display native values
- display in sRGB
- display in Generic RGB
- display in Adobe RGB
- display in L*a*b*

and there is also a box indicating which color sync profile is active on mac right now.

I get confused about two things:
1. What is the meaning of "native values" here ?
2. What is the actual influence of the color sync profile active on the mac ? I mean, if I display your proofing image with the cat in any application (photoshop, vlc, quicktime, fcpx) the measured values from DCM change when I change the color sync profile.

As an ending note, I have only a MacBook Pro. No monitor whatsoever for grading. I know it is not ideal but I don't have the money. I only calibrated it with a Spyder for photographs.

So I would like to know if there is any way of getting the MacBook to display the closest possible image to that of a broadcast monitor to color grade a movie in DaVinci Resolve.

Thank you very much !

R.


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