REC709 and sRGB - no color management difference

[Milan_Michalik]

We know, there is only a gamma difference (to make it simple) between REC709 and sRGB and this gamma difference is quite important for serious work.

I never used color management in AE in the past, because it slowed down the fps for the preview.

Yesterday I wanted to check how it works in CS6 and I found out this:

There is no difference between REC709 and sRGB in color management in After Effects CS6 Win or Mac?

I set the color management on and choose REC709.

I import a footage (I tried every possible format - stills, video, video seq... with or without embeded profiles).

In interpret footage box - if I choose something weird like Film or cieRGB or widegammutRGB, I see the change in the viewer.

But if I am switching between sRGB and REC709, I see no difference.

I see the message, that the gamma will be corrected from 1.9 to 2.2, but it is not happening.

Well... I used the similar concept in Nuke and Smoke and it works there, just I don't know what I am doing wrong in AE ?

And yes, I read all the help files and tutorials 10000x.

Thank you for any ideas in advance.

Milan

[Mylenium]

Well, but do you actually use color management onb your system, i.e. a monitor profile?

Mylenium

[Milan_Michalik]

Yes, I do. I use sRGB monitor profile - because my monitor is not REC709, but sRGB. Just I do not understand, why you are asking this question 🙂

Again, on the same system, in NUKE, when I set my project as sRGB and when I switch my input footage to REC709 instead of sRGB, I see the difference in gamma.

When I do the same in AE, I don't see the difference. REC709 or sRGB - the same.

[Mylenium]

Well, working with color profiles makes no sense on an unmanaged system, that's why. Do you actually assign the profile for comp preview/ use it in Nuke? As far as I'm concerned, I see nothing wrong here. Seems more to me like you are working unmanaged in Nuke and are misinterpreting it's lack of Gamma compensation for how things should look in AE...

Mylenium

[Milan_Michalik]

Well... I speak about apples and you about oranges.

AGAIN.

It doesn't matter what is your project profile.

Just focus about video interpretation. Every single professional application like Flame, Smoke, Nuke, Avid DS asks you, what data you are importing into the project.

If it is linear, or REC709, or sRGB, or filmlog, or ARRIlog, or REDfilmlog....

Just because the application wants to convert/handle this footage well and show you the footage right on your monitor.

Can you answer me a simple question?

Why is the sRGB and REC709 considered as the same profile for importing footage?

Please do not aswer me about bananas. Answer me only about the question above.

It seems to me right now that the color management is a big joke and I have to use LUTs...

Or maybe, I have to find the AE config data for color management myself on the disk and modify the AE gamma data...

[paulinventome]

AFAIK there is a difference between REC709 and sRGB curves, they're not just gamma curves, i can't remember off the top of my head but the shadows flatten out into a linear line with one of them. Whether the difference is enough for you to worry about depends on what you're doing. You can see the LUTs in Nuke on the project settings and compare the curves.

There should be a difference applying a REC709 vs sRGB profile on injest. Are you in 32 bit float project mode? Your viewing LUT/profile is set to sRGB? What is the footage and format you're importing? Is there something in that footage that is overriding your selection?

You can also not apply a profile on injest and apply one via an effect afterwards, perhaps try that to see if you can see it working

Sometimes AE attempts to be a little too clever and automatic, whereas Nuke tends to leave it up to you and not 'auto decide' anything.

hth

paul

[Milan_Michalik]

Hi, finally someone who is with me 🙂 and I see that you asks good questions 🙂

I know that there is more difference then the gamma (this is why I wrote: make it simple) in my first topic.

"Is there something in that footage that is overriding your selection?"

Right question. This is what I am asking too. But I've tried all codecs and all formats, even stills, with embeded and non-embeded profiles. What should I test more?

"Are you in 32 bit float project mode?"

I tried 8bits, 16bits and 32float too.

"Your viewing LUT/profile is set to sRGB?"

Just right now my windows monitor is set to sRGB, my After Effects color management is set to sRGB. And my footage is REC709. So I see it's too dark in sRGB color space, I see less resolution in blacks and my picture is darker.

I opened AE and Nuke on the same time, same computer, same monitor, same footage.

I set sRGB for Nuke and AE as a color space. Viewing color space is sRGB on both.

Read node in NUKE: colorspace sRGB = picture is darker, colorspace REC709 = picture is correct.

Import interpret footage AE: colorspace sRGB = picture is darker, colorspace REC709 = picture is darker, no change

THERE iS EVEN MORE !

If I set simulate output view to REC709 instead of sRGB, my AE composition stills the same.

If I do the same in NUKE, it changes of course.

I see I have to build a LUT and use this workflow in AE, just I wonder that I am alone in the world who cares about this problem???

I am not an NUKE artist or employee, who wants to promote NUKE, or other application. I own After Effects and I want to use it in a right way.

5 minutes ago I tried the same on Mac = same problem Win/Mac = so it isn't my computer fault.

So the question is: Is there anybody who sees a difference in the picture when you injest (import) a footage in 2 different ways, first as a sRGB and then as a REC709???

[paulinventome]

Im not in front of my workstation at the moment to sanity check this.

But you should be seeing a difference, so it points to something not quite being right in your set up.

You shouldn't have to build a LUT to use REC709 or any supported colour space footage, intepreting the footage should work as you expect, and as it does in Nuke.

How is your color management set up? There's a dialog for that and has a number of settings, not all are obvious?

I've compared Nuke and AE and they should be similar. AE is let down a little because a lot of the plugins aren't 32 bit float and some operations you do can also truncate colour. But taking footage in and out should be fine.

cheers

EDIT: which Rec709 profile are you using? There's one that uses the legal range 16-235 and one that's full range. If you use 16-235 on full range material you'll clip your blacks and highlights - it's not something like that is it?

paul

[Milan_Michalik]

I use full range REC709 and no plugins... let's wait for your workstation or for other volunteer to check it 🙂

[Guest]

sRGB and Rec.709 have the same primary colours and the only difference is gamma.

You won't be able to see a much difference between them in gamma corrected (non-linear) working space, which is default in After Effects (you set your working space into linear light by ticking Linearize Working Space checkbox). But Nuke, as far as I know, internally works in linear light.

If your full range Rec.709 footage exported out of Nike looks too dark in AE, chances are you exported it in linear light.

So as to correct that you need to interpret your footage properly: right-click it in the Project panel and choose Interpret Footage -> Main... In the Color Management tab choose Assign Profile: HDTV (Rec.709) and Interpret As Linear Light: On.

Report how it goes.

[Milan_Michalik]

Thank you but... same result... no visible change 🙂

[Guest]

So as to save some time on guessing what you're doing wrong, post a screenshot of your 'properly looking' footage in Nuke and upload exported footage so that we can check on our own (Dropbox is a nice tool for file sharing).

[Milan_Michalik]

Here are the files:

http://www1.datafilehost.com/d/f2f23ece

Just imagine following scenario: (pretty standard).

You shoot something and the client wants you to add some graphics into the video and make 2 deliverables, one for broadcast TV and 1 for Youtube.

Just to make it very simple, let´s do it on a notebook without external preview (broadcast monitoring is another big issue for AE).

So I put the footage into the DaVinci and I did colour corrections/grading. I exported REC709 QT file - 10bit RGB Blackmagic.

You find the mov file in the archive above.

I am using the sRGB profile on my  laptop LCD for DaVinci.

Then let´s make a new Nuke project in sRGB space, just because we use notebook and  the only option for monitoring our project is the laptop LCD only.

Let´s import our footage. Upsss. It looks darker. Ahhh...o.k. we exported REC709 and not sRGB from DaVinci so we need to interpret it right.

Let´s open the Nuke Read node and set the footage as REC709. Now the footage looks like in DaVinci.

So we are in sRGB only and we can add graphics from Photoshop - it will be probably sRGB too, so it will fit.

Now we have a final video and we need to deliver it. For broadcast TV I set the write node colorspace as REC709 and I do the export.

For YouTube a set the export colorspace as sRGB and I do the export.

If you open the export test tiffs (from the archive above), you see that the result is different.

This is how it works in Flame, Smoke, Nuke, Avid DS... etc etc.

Now the question is: how to make the same workflow in After Effects. If I do not  interpret the video REC709 to sRGB, then I am mixing REC709 with sRGB graphics.

And this is what you see 99% on YouTube. Dark video with bright graphics elements.

Well I am sending you quite right balanced footage, the difference is not so obvious.

But for problematic shots it is a big difference. And for pro jobs...

Howgh 🙂

[Guest]

I exported REC709 QT file - 10bit RGB Blackmagic...

I don't have Blackmagic codecs installed and am not in the mood to troubleshoot crooked DesktopVideo istaller, which just hangs in the middle of the process (generally speaking, I gave up on it quite a while ago, but that same issue persists in the DesktopVideo 9.7.2 installer). Hence, I can't test your MOV file, unless you share according .QTX files for QuirkTime for Windows...

Judging on your exported TIFFs, some extra conversion happens somewhere in your pipeline. If I set my AE project into 32-bit sRGB colour space, linearise working space (so as to get the same environment as you have in Nuke) and then apply Color Profile Converter onto your Rec.709 TIFF (interpreted as Rec.709 in the Project panel), converting it from Linear sRGB to Linear Rec.709 (16-235), I get something close to your sRGB TIFF:

'Difference' between layers in linearised working space looks like the following:

And in gamma corrected (non-linear) working space accordingly:

broadcast monitoring is another big issue for AE

And what exactly?

Now the question is: how to make the same workflow in After Effects

In exactly the same way:

1. Set up your project;

2. Import and properly interpret footages;

3. Assign colour profile in the Output Module Settings.

See this help section.

[Mylenium]

The feline hit it on the head - in an environment that uses any form of Gamma correction, the differences would be minor or non-existent. All Adobe apps obey the operating system's default Gamma and based on their interpretation rules and the hardwired stuff in the file format plug-ins also the Gamma values as defined by the format spec, then the color engine does its magic, adding a further level of control with color profiles where necessary.

Mylenium

[paulinventome]

This is one area that seems to be a bit confusing in AE vs Nuke.

Fuzzy: Nuke, very simple. 32 bit linear float internally. Viewer has an appropriate LUT (default sRGB, but could be REC709, P3 whatever you're monitoring on). All input footage needs a profile to linearise it into float be that sRGB or 709.

Of course once we get into ACES then it starts getting more complicated but we'll skip that one for the time being.

I double checked and it's sRGB that flattens out at the bottom of the curve, it does make a difference, subtle but it's there.

I'm working in 32 bit float in AE too, once i get back then i'll check my environment out.

cheers

paul

[Guest]

Fuzzy: Nuke, very simple.

And which difficulties exactly are you facing in AE?

I double checked and it's sRGB that flattens out at the bottom of the curve, it does make a difference, subtle but it's there.

And how does it contradict with or append to the definition, which states that sRGB has 2.2 gamma and Rec.709 - 1.9? Do you understand what that curve represents?

[Bob Currier]

Pedantry ahead! This doesn't directly address Milan's situation, but there is a bit too much oversimplification going on here for my taste.

Neither Rec.709 nor sRGB have simple power function "gamma" curves. Both include a flattened section near black to avoid the asymptotic nature of a straight power function.

Rec.709 uses a power function of 0.45 (1/0.45 = 2.2), but includes a linear portion with a slope of 4.5 below the tristimulus value of 0.018. This gives it an actual transfer curve approximating a power curve of 0.5. This is at the encoding (camera) end of things. Rec.709 the assumes the display will have a power curve of 2.5. This gives an end-to-end reproduction of 1.25, which is subjectively correct, although it is not mathematically linear. And to further confuse things, most current television sets have a power function of 2.6 or higher.

sRGB similarly uses a power function of 0.42 (1.0/0.42 = 2.38), but also includes a linear portion, giving an overall transfer function approximating a pure power function of 0.45. Assuming the same display as with Rec.709 (with a power function of 2.5), then end-to-end reproduction is 1.125. This is considerably lower than with Rec.709, and is intended to compensate for the fact that computer screens are typically viewed with higher ambient lighting than televisions. It was the intent of the sRGB standard creators that images not only look the same on different computers and monitors, but also that sRGB images on the computer (high ambient light) should give the same subjective contrast experience as Rec.709 images viewed on a television (low ambient light).

Given that most people calibrate their monitor to 2.2 instead of 2.5, things are already broken. And certain expensive name-brand HD video monitors still use Rec.601 constants. Sigh...

[Guest]

'Homie understands colors' ©

[Milan_Michalik]

To Bob Curier:

Yes, I spoke only about gamma, just to keep everything simple. It seems to me, that AE users don't care about the picture difference rec709 vs sRGB at all.

[Guest]

It seems to me, that AE users don't care about the picture difference rec709 vs sRGB at all.

And how did you reach this conclusion?

[Milan_Michalik]

Sorry man, I give up. My english is quite bad and you probably don't understand the point.

Can you please do the last test for me? And then I will shut up.

Make a sRGB color management project. Even 8bit is o.k. Import some footage, or still. Turn ON the SIMULATE PREVIEW in viewer and choose REC709.

Do you see any change in the viewer? In all other software (Smoke, Flame, Nuke) I see the change.

[Guest]

Set your After Effects project to 32-bit and linearise working space.

Choose sRGB colour space.

Create a test comp with a solid and apply Ramp Gradient.

Optionally apply a mask on a solid and duplicate it as many times as you want so as to get several synthetic bars, e.g. four ones. Change Ramp Gradient colours accordingly so as to get Black -> White, Black -> Red, Black -> Green and Black -> Blue gradient bars.

Change your working space from sRGB to Rec.709.

Do you see any change?

Sorry, Mylenium was right when he gave up on you...

[Milan_Michalik]

I did this:

Set your After Effects project to 32-bit and linearise working space.

Choose sRGB colour space.

Then I imported my footage

Change your working space from sRGB to Rec.709.in viewer

Sorry, I see no change. I don't care if the internal solids and gradients work, this topics is about interpreting an external picture/video.

I give up as I promised 🙂 and we all will be happy till the end of our lifes 🙂

[paulinventome]

Milan,

I have to say it works for me. I created a new AE project. In project settings i have 32 bit float. Working space is sRGB and linerarize working space is on. I have match legacy gamma off and also off for compensate scene referred profiles.

I import both your REC709 and sRGB files

Drag them to create a comp and as standard the REC709 is darker than the sRGB. If i interpret that 709 footage and add a REC709 profile then that image now matches the sRGB.

This is exactly what i'm expecting to see. I note that your REC709 image is full range 709, so don't use the legal 16-235 version of the profile as it will clip and seem darker.

Bob, you are quite correct of course, although i thought sRGB was a simple power function. Live and learn. Also i believe there's some varibility about what the 709 function actually is, sometimes is approximated. This is from a course from Charles Poynton a while ago so memory is perhaps not serving me 100% but the reality is as you say - sRGB and REC709 are different enough beyond a gamma curve, especially in shadows.

Fuzzy, you seem a little harsh. Milan said that his english wasn't that good and what he's seeing is not what he should be seeing. So lets help the guy see properly.

cheers

Paul