Color Management for Video???

[nkp]

I know a bit about color management for stills.  How does one do color management for stills?

>>  Is the technology similar to that for stills?

>>  Do computer operating system include technology for color managing video in the same way that OS's include technology for stills?

>>  Does color management for video use the ICC standard?

>>  Is there a reference I can read to learn more about this topic?

Thanks.  I'm trying to get the lay of the land for video CM. 

[Doug Gray]

I know a bit about color management for stills.  How does one do color management for stills?

>>  Is the technology similar to that for stills?

>>  Do computer operating system include technology for color managing video in the same way that OS's include technology for stills?

>>  Does color management for video use the ICC standard?

>>  Is there a reference I can read to learn more about this topic?

Thanks.  I'm trying to get the lay of the land for video CM.

Here's a good source on color management issues related to videos:

ACES is a free, open, device-independent color management and image interchange system that can be applied to almost any current or future workflow. It was developed by hundreds of the industry’s top scientists, engineers and end users, working together under the auspices of the Academy of Motion Picture Arts and Sciences.

https://www.oscars.org/science-technology/sci-tech-projects/aces

[digitaldog]

What's most important is to determine if the products editing or viewing the video supports color management.

[Christopher Sanderson]

I know a bit about color management for stills.  How does one do color management for stills? {video?}...

You are already ahead but Colour Management and Correction for video are operationally quite different. Especially for the beginner. Different colour spaces as a starter... Once you understand the differences, you will find your stills knowledge will give you a huge boost and you will learn quickly. But the entry and tools used will be quite different for you based, for better or worse, on fifty-plus years of broadcast colour management. The good news is that the technology of video is becoming closer to that of stills.

If you want to really get in to the subject, I can highly recommend Alexis Van Hurkman's book Color Correction Handbook 2nd ed.

While the book was published in 2014, all the principles and techniques still apply.

[smthopr]

I know a bit about color management for stills.  How does one do color management for stills?

>>  Is the technology similar to that for stills?

>>  Do computer operating system include technology for color managing video in the same way that OS's include technology for stills?

>>  Does color management for video use the ICC standard?

>>  Is there a reference I can read to learn more about this topic?

Thanks.  I'm trying to get the lay of the land for video CM.

At the moment, color correction for video and the applications that do this, are not color managed with .icc profiles, so the workflow will be different.

In general, the display is calibrated to a standard video color space such as REC709 or P3.  IOW, the display shows the colors in the standard color space with no input from the color correction application or the OS.  This calibration is accomplished by using display calibration software solutions/probes made for video, such as Lightspace, Calman, or Displaycal (open source).  A 3d LUT is created that can be used as an output LUT in your color correction software, or placed in a LUT box between the video output connection and the display input.    To guarantee a correct signal to your display one usually uses a special video output card that does minimal image processing, but sends an unadulterated video signal to the display.  Something like a Decklink card from BlackMagic. (If you use Davinci Resolve, this is what you will need.

So, if your display is set to REC709, that will be your "working color space".  To change the working color space you will need to change the calibration LUT for your display to something like P3 color space that is used for cinema projection, but not for TV.

I would check out liftgammagain.com forums for more information as it is a much discussed topic there.

I would not suggest looking into ACES color management yet, as that will just confuse you, and it also requires the same steps to calibrate the display.

I am a cinematographer that has done a bit of color correction for feature films in my home.  For example, I am using an Eizo wide gamut computer display.  It is pre set to it's native color space, and "calibrated" using the ColorNavigator software made for the display.  This calibration is stored in the display, as one would do with an NEC computer display.  But I'm not yet calibrated to a standard video color space.  To do this, I am using Displaycal software to measure the state of my display with an iOne Display Pro device (in it's native gamut) and create a 3D correction LUT to enable the display to correctly display REC709, gamma 2.2.  I load this LUT as a display output LUT, into Davinci Resolve software to make my display corrected to the video REC709 standard.  And then, without using any "color management" options in Resolve, what I see, and therefore, my working space is correct REC709, gamma 2.2 color space.  My display is connected through a Blackmagic Decklink video card to ensure that there is no OS input into the signal that might alter the colors.

So, in general, video color management is not as simple as simply getting an iOne probe and using iOne display to store a calibration/profile in the OS like one would do if using photoshop.

Welcome to video color correction!

[Aram Hăvărneanu]

Bruce is right. Last time I checked (a couple of years back), the ONLY NLE that worked with any profiled display, and didn't require special LUT boxes, or special monitors that could load LUTs in hardware to emulate video standards was Final Cut Pro. With Final Cut Pro the workflow is like with Photoshop or with any other software for photography. You profile the display (any display), and using color management the color will always be consistent between different displays.

Not so with other video software, there you need to somehow make your display emulate a standard like REC709 or P3 or whatever is your target space.

But wait, it's worse. There are only two color-managed video players on the market. iTunes/QuickTime, and mpv (open source). Unfortunately color management is turned off by default in mpv, and while you can enable it, it's very buggy. Another fellow and I tried to work with the mpv developer to fix the color management bugs in mpv (I am a programmer), but that experience was very frustrating, some self-proclaimed "video expert" got involved, and now mpv is worse then it used to be. It's hopeless. VLC is not color managed. I read the source code and making it color managed would require significant changes to VLC's code base. It won't happen without significant effort.

I am running my own mpv build, with my own fixes, that makes it colorimetrically correct, but without black point compensation. Some day if I have more time I will try to get mpv fixed upstream once and for all, albeit that will have to be without black point compensation. Both the mpv, and the LittleCMS authors are afraid of BPC because of fear of patents, aaargh.

[smthopr]

Bruce is right. Last time I checked (a couple of years back), the ONLY NLE that worked with any profiled display, and didn't require special LUT boxes, or special monitors that could load LUTs in hardware to emulate video standards was Final Cut Pro. With Final Cut Pro the workflow is like with Photoshop or with any other software for photography. You profile the display (any display), and using color management the color will always be consistent between different displays.

Not so with other video software, there you need to somehow make your display emulate a standard like REC709 or P3 or whatever is your target space.

But wait, it's worse. There are only two color-managed video players on the market. iTunes/QuickTime, and mpv (open source). Unfortunately color management is turned off by default in mpv, and while you can enable it, it's very buggy. Another fellow and I tried to work with the mpv developer to fix the color management bugs in mpv (I am a programmer), but that experience was very frustrating, some self-proclaimed "video expert" got involved, and now mpv is worse then it used to be. It's hopeless. VLC is not color managed. I read the source code and making it color managed would require significant changes to VLC's code base. It won't happen without significant effort.

I am running my own mpv build, with my own fixes, that makes it colorimetrically correct, but without black point compensation. Some day if I have more time I will try to get mpv fixed upstream once and for all, albeit that will have to be without black point compensation. Both the mpv, and the LittleCMS authors are afraid of BPC because of fear of patents, aaargh.

Quicktime is not color managed in any successful ways, so I always avoid using it to judge the image.

And I'm not sure that BPC has any application to video display.

In fact, right now, the only way to correctly judge a video image is to play it completely un color managed to a display calibrated to the standard that the file has been color corrected to.  As I described in my previous post, that really means using a video output card (not the computer graphics card) to output the video stream with no color adjustments of any kind to a display calibrated to the standard.  Anything else is just guess work.

[GWGill]

Thanks.  I'm trying to get the lay of the land for video CM.

Depends on what you mean. If you mean color management within the video preparation workflow, then typically these are proprietary and depend on the editing tool being used, or perhaps are based on standards like ACES if there is any inter-operability.

If you mean color management of displays for monitoring or proofing video, then these fall into two camps:

1) Color management aware companies/products such as Adobe etc. They use ICC like any sensible person would.

2) Color management un-aware companies/products, which rely on displays being calibrated to particular video encoding standards. (Some of them seem to dis. ICC & color management, because they don't understand it. To them, the ultimate is a "3DLUT", even though this is exactly what ICC provides.). You either use a very expensive monitor that is set to these standards (i.e. Sony, Flanders Scientific etc.), or you calibrate the display itself or use extra software and/or hardware to do the transformation from the standard colorspace to the particular display. Various calibration programs are available in the video sphere, including Calman, Chromapure, LightSpace. Free options are HCFR and DisplayCAL/ArgyllCMS.

[Alan Klein]

Who actually knows the video is color corrected unless they are looking at it thru a color calibrated monitor for video?  Also, and this may sound stupid, what is color corrected video?  WHen I shoot video clips with my Sony P&S RX100iv, and edit it in Photoshop Premiere Elements, I only adjust brightness, shadow details,  and simple stuff that that.  WHen I look at the color, it looks OK.  Why would I change it? 

[Alan Klein]

I do use a NEC calibrated by SpectraviewII for sRGB. 

[GWGill]

Who actually knows the video is color corrected unless they are looking at it thru a color calibrated monitor for video?

Those people who know and implement color management are able to do this without using a calibrated video monitor.  A calibrated display is the least flexible means of reviewing video material. (i.e. it can only display output in one colorspace encoding at a time. True color management can display multiple color correct images on the same display simultaneously.)

Also, and this may sound stupid, what is color corrected video?

Color corrected video is video that has been adjusted by the creative arbiters (typically the Director & Colorist in a professional product) to look as they intend, when viewed in a reference display environment. A reference display environment is one where the colorimetric behavior of the display and the viewing environment match the technical definition of the video encoding format the video is in.

[Alan Klein]

I can see if you're producing a Hollywood or advertising film where different video cameras have to be integrated to give the same color rendition.  Then you'd want to have some sort of a calibratable system to make all the media look the same.    But why would that be necessary for home use if you're using one camera?  Can you give examples?  I can see and already do adjust shadow areas or add saturation a little in Premiere Elements.  But that's only to please the aesthetic in my own eyes.   Also, to match the look of stills taken with the same camera where I have changed their look in Lightroom (ie. color saturation) and would be part of a combined slide/video clip 4k TV presentation I do at home for my travel vacations.  But beyond that, why would I color correct videos any more than I color correct stills?

As an aside, I know people are using Log 2 or something when they shoot video.  I have it on on SOny RX100.  What is the purpose of using that setting?  How would that help for home use?

[smthopr]

I can see if you're producing a Hollywood or advertising film where different video cameras have to be integrated to give the same color rendition.  Then you'd want to have some sort of a calibratable system to make all the media look the same.    But why would that be necessary for home use if you're using one camera?  Can you give examples?  I can see and already do adjust shadow areas or add saturation a little in Premiere Elements.  But that's only to please the aesthetic in my own eyes.   Also, to match the look of stills taken with the same camera where I have changed their look in Lightroom (ie. color saturation) and would be part of a combined slide/video clip 4k TV presentation I do at home for my travel vacations.  But beyond that, why would I color correct videos any more than I color correct stills?

As an aside, I know people are using Log 2 or something when they shoot video.  I have it on on SOny RX100.  What is the purpose of using that setting?  How would that help for home use?

To keep this simple Alan, if you shoot .jpg still photos and display them, you might be all done.  It's the same with video.  If you shoot with your camera set to REC709 video, it's like shooting .jpg and, for home use, you could be all done.

But many still photographers shoot RAW (uncorrected images) or... even negative film.  Shooting in these formats requires color correction to make even a "normal" looking image.  The advantage over .jpg is that you are recording in a higher bit depth and not clipping any information that the sensor can capture, so that you have the maximum flexibility to create your vision.

It's the same with motion photography.  There are some cameras that can capture RAW images that require color correction, plus there is also "LOG" capture that is a compression solution that holds all the sensor data in a container that is compatible with color corrected images.  Essentially it is capturing a very low contrast image that requires color correction to look normal.  And there is also film capture for movies too.  And that also requires color correction or you'll be looking at color negative images

At this date, there are no motion picture color correction apps that work with .icc profiles like photoshop.  So, the only solution is to view a straight video signal on a display set and calibrated to the standard.  That's where we are at.

I believe the current situation with video color correction stems from electronic video color correction having begun when there was only one standard display: The CRT display.  A "standard" professional CRT display had only one color space built into the device, so all color correction was done in this standard working space.  .icc profile color management systems came later for computer graphic use, but at that time, video was still married to the CRT display, so it was of little use.  And video color correction requires intensive processing as many frames need to be processed quickly for real time playback. I think the app developers did not want to add further processing steps that could slow down the process as real time playback was still difficult.

Cut to: Today.  In video we now have digital cameras that record data beyond the old TV standard color space and we have multiple output color space standards and further, displays that are "wide gamut" and can show colors far beyond the old TV standard/CRT colorspace.  But, because of the evolution of motion picture color correction apps, we are still working in the old, non color managed, scheme.  To bridge this "gap" we must adjust our displays to the working color space of our project to see images correctly.