Let’s not use the term “gamma”. It is ambiguously used in different context and it often confuses both the people using the term and the people hearing it. I bet many of you guys don’t really know what the term “Gamma” originally means.
So the term Gamma was really supposed to be a variable in the Power Law function. And this Gamma itself when taken out of that Power Law Function context, doesn’t mean anything other than a greek letter.
For example, I am writing a math function f(x) = x +1, and now I refer to the function as “X” wherever I decide to use it without mentioning the original fucntion at all. Do you see the madness now?
The thing about using “Gamma” without the context is that now people are using the term gamma while they have no idea what a power law function is. Therefore people don’t actually understand what Gamma really stands for, and they use the term as what they thought the word means.
“With or without Gamma”, what does that even mean? How can a power law function be without that variable? This is what happens when you use the word “Gamma” nowadays, ambiguous meanings.
I guess what you mean is “image can be saved with Linear encoding or non-Linear encoding”. Note that not all non-Linear encodings are power law function. For example, sRGB has two standard functions, one for encoding and one for display (the original intension was to create a mismatch in encoding and display to darken the image for flare compensation, but this approach is sort of out dated and the new school approach would be using the same function to do a “no operation”, this is covered in the Chris Brejon article I linked above). So yeah there are two sRGB transfer functions, one is power law function 2.2, the other one is a piece-wise function that darkens the shadow. The piece-wise function cannot be described using pure power law function, therefore if you try to reference it using Gamma it will be completely wrong.
So guys, don’t use Gamma, use proper words like “Power Law Functions” or “Transfer Functions” or “Non-Linear Encoding” etc. instead, depend on what you really mean.
Also sadly Blender still has the “Gamma” node and the “Gamma” setting in Colormanagement panel with this ambiguous name, I hope one day it gets changed into “Power Law” node and “Inverse Power Law” setting in CM panel to avoid all the ambiguity. (And yes they are inverse, I don’t think people realize it because they mostly use the term “Gamma Correction” to refer to both, I mean you can see how confusing it is now.)
AFAIK you are correct with that behavior, one thing though is that the behavior is not what “Linear sRGB” means.
The colorspace option in Blender’s texture node has a full name, “Source Image’s Colorspace”. Therefore it’s a setting for you to mark what the original image was encoded in. Then OCIO will transform the image from the colorspace you mark it as, to the “Scene Linear” colorspace specified by the OCIO config. Therefore “Linear sRGB” means the original image was encoded in sRGB colorspace with a Linear transfer function. The conversion thing is just what OCIO does.
This is not really Filmic nor ACES, this is OCIO. That’s why in the beginning of the thread when people said something like “ACES means you take images from different colorspaces and unify them in the same working colorspace”, I told them this is the approach already with just OCIO.
I would prefer the term “encoding” rather than “format”