Last edited by lsscpp; 16-Jan-17 at 06:19.
Everything's relative. Even saying "Everything's relative".
I've actually said that it was just a friendly talk with no intent of going deep on subjects.
And good. It was already on suggested targets last week, now it's official.
Not surprised since the effort needed to put it in master is close to 0 and the benefits are huge.
Little OT (more or less), not sure if there is some issue with IES support and disney shader to be eligible for the master, probably they are not finished yet, but their inclusion would be a good news too.
Sorry (maybe not the right place to ask) but does anybody knows if Natron is OK for post production or even if it can used in conjunction with filmic_blender? I can load filmic_blender config.ocio in my color management where the default is blender. Is this valid or am I doing something wrong? I'll also repeat this question in Natron forums. I've read troy_s mentioning in a post that some things are "broken" in blender compositor, also on PS and GIMP so I guess we need another compositor for post production
Last edited by SunBurn; 16-Jan-17 at 11:56.
If you in post production try to do the math in your mind between scene referred values and display referred values you'll get unexpected results.
I make you a math example with no reference to real value, just a math example.
If you have your render with a value on a point, let's say, of 2000 and you want to multiply it for a value of 0.5, you expect the result must be 1000, that after the EOTF (Electro to Optical Transfer Function, which is pratically the encoding transformation from an electrical input to an optical output signal, from scene referred values, linear signal, to display referred values, non linear signal), would end up in 1.
But you'll end up with a result of 0.5 simply because the math you did was not done in scene referred but in display referred, so after the EOTF. You think something is broken.
To summarize in poor words, what's broken and what's working?
It's broken the math operation done on display referred data, so after the transform.
It's working the math operation done on scene ref data.
Is there a list of those broken math operation in blender compositor?
Honestly I don't know blender compositor, and its code, that much to say it, probably all that Adobe operations of blending that are also in the compositor are broken because they are natively intended to work on display ref. non linear values.
This includes also photoshop as a non good candidate if you need for example to work with EXR because it natively works on non linear signals.
It is wrong to work in display referred?
Personally I think no, but you'll end up with losing data, how much that data is useful it could depend.
Let's say I'm not that nazi-purist thinking.
So Natron and others?
I don't know, as said I'm not that much into CM.
I suggest to use whatever software you find comfortable without being extremely paranoid, until you get something unexpected.
What I really suggest is to try to put in the blender's 3D scene as much elements as possible, first of all because of correct energy balancing between elements, second because you're sure that blender compositor works on scene ref data, with the exception of those broken operations that would be nice to know.
If something is wrong, please correct it, I admit my high% of ignorance in matter and I've tried to answer just because I've seen not much people did.
Thank you for your answer.
Here's a link to Natron forum where I've also opened a thread.
here's the most important answer so far:
And here's what I understand combining all the information from both posts. Correct me if something is wrong.Keep in mind that the filmic blender is designed to deal with scene referred data and using a much wider Dynamic range than the default sRGB, so it only makes sense if you are using EXRs or other formats that are not display referred.
The Filmic blender is designed to deal with the unnatural saturation that CG images produce when it comes to dealing with bright values. So it only makes sense to process GC images through it and not images form photographic (or video) sources.
You can take full advantage of filmic_blenders power only if you save your image to full float EXR or immediately after you finished you render before applying any Display Transform.
That means passing the rendered image to Compositor and apply your Color Correction there and save after all.
The problem here is that many blender compositor nodes are build to work with Display referred imagery (EOTF/sRGB) and not Linearly so they should be avoided cause they don't take advantage of all the information that there is.
As far as it concerns Natron the same things are true.
If you want to take full advantage work with EXRs any other format seems kind of limited since you'll be working in Display referred space and all the color and light information are already processed.
Maybe I've simplified things a bit and also English is not my mother tongue but this is how I understand it so far.
Here's also a useful link where troy_s explains it a lot better.
If an application has proper DPX support, this would be the ideal format to encode your Filmic Log Encoding Base to. Sadly in Blender, the DPX code is totally broken and it can't work.
Once you are in the nonlinear domain however, beware of things that won't behave "correctly" such as blending, painting, blurring, etc. For these sorts of transforms, only properly linearized visual energy will avoid fringing, bad blends, etc.
Natron should be able to load the OCIO configuration properly for use, but last I looked their developers had some lower level broken bits on the viewer etc.
As for broken things in Blender, these are left for the folks who have been experimenting with proper scene referred rendering to discover. Note that the broken bits have been there ever since Matt Ebb first added the sRGB linearisation code years ago, but few had enough of the knowledge pieces to see them clearly. Here are some things to try:
- Curves. Try using false colour and moving part of a curve to adjust the middle grey zone of your image. What happened? Where did you grab the curve? What did you expect? What about the red range? Where did you need to grab it? What did you expect? How would you design the UI to repair this brokenness?
- Colour Mix: AdobePDF Blend Modes. Overlay, Soft Light, Hard Light, Screen, Linear, etc. Why are these broken?
- Lift, Gamma, Gain. What happens?
- 'Gamma' related blur toggle. Why is this ridiculous in modern Blender?
See if you can find more. There are many broken little Easter Eggs in Blender, and it behaves better than most applications. With more folks discovering the nuances of proper scene referred image editing hopefully these problems can be fully understood and ultimately, repaired.
Last edited by troy_s; 17-Jan-17 at 22:19.
Thank you for the answers, some things are more clear now.
On the other hand I have more questions to ask, more topics to read and more tests to do ...