I have to say the more I try AgX, the more skeptical I am. I have a smart light bulb at home that can create some extremely saturated colors. When I look at the light from the light bulb directly with my own eyes, I see nice deep red color even in the highlight. Only when I take a picture in my phone does the phone tonemap the image so that the red fades into white around the highlight where the light bulb is near the wall. But once again when I raise my head from the phone screen to look at the reality, there’s no fade to white, it’s just really deep intense red color.
If the point of these types of color transforms is to bring rendered data as close to what eye would see in the real world on a limited dynamic range monitor, then AgX is even step back from filmic. AgX seems to go on way too aggressive crusade to defeat hue shifting around highlight that it gives up pretty much everything else for it. It’s certainly not better in terms of making computer imagery colors match real world closer.
This is the photo I took and how it looked with Pixel 6 image processing, the hue shift is there even on a photo. It’s kind of similar to how Filmic would handle it:
This is a quick image edit to reproduce what it looked like to my own eyes, there was really no hotspot:
And this is how AgX would make it look like:
To me it seems that both Filmic and AgX fail to represent the real world perception of saturated color. It’s just that they both fail at it from the opposite sides of the problem.