I'm starting to believe that there are 2 simultaneous conversations happenings because there is a lot of overlap between the two, they look like a single conversation. I'm hoping this post would help see everything more clearly.
Last time I did some cornell box tests and some of you rightfully noted that it is not a sufficiently conclusive test as it is a simple setting with no dramatic light or materials. I decided to run a second test. My goal is NOT to say: Corona is as good or better than Fstorm, because I actually don't know.
My goal is to find out WHY people seem to think Fstorm is SO MUCH BETTER in terms of color management. And to find out if it is, maybe I should switch to Fstorm.
Disclaimer: I never used Fstorm before yesterday.
For that reason I set myself a few requirements:
1. The scene should be based in a Johannes L. Image, since that's what most people refer to when they say "Fstorm handles color better"
2. The least number of materials. Since I will have to replicate them in Fstorm and I'm a noob
3. Real World use. Something that a client would ask for.
4. Basic lighting
Ok, so I found this perfect scene by Johannes L. I set it up using just 4 materials. Corona Sun and Corona Sky. For Fstorm I used Fstorm Sun and Fstorm Sky. I left everything I could at default, only played with white balance to match colors on both engines.
Maybe it would be more "correct" to load the same HDR in both engines instead of using the stock SUN and SKY system. But I figured they are close enough, and an accurate representation of the available tools.
First, this is the image I'm trying to approximate:
This is what I get out of both engines by default:
Ok, sure Fstorm is in fact producing a more pleasing and "photographic" by default. But you can see it is nowhere NEAR what Johannes makes.
Next is to enable everything I usually enable in Corona. This is my default workflow and the only thing I needed to tweak to come closer to the original image was a greater contrast value (usually 3 or 4, this time 7)
As I showed in my previous example, the image changes dramatically.
Here is a before and after:
Then I tried to match the Fstorm Default with as few settings as possible. To me, it looks like highlight compression plus contrast does a good job.
You can see how my workflow produces more "photographic" images than Fstorm default. I must say that I use these settings for 90% of my renders. And only tweak in specific cases. I usually do most of the project in my default settings and only tweak at the very end (Curves, contrast)
I wanted to see what would happen if I loaded Kim Amlan 02 LUT into Fstorm. I needed to tweak the "burn" value a little bit. I tried to move the least possible settings. I bet an experienced user would be able to get a better result, but this was very interesting to me.
Yes, of course, there are slight differences. Their SUN and SKY models are different, so maybe that's why colors are a little different. And the reflections don't match. I don't know how to properly use Fstorm materials so I did what I could.
But after this experiment, I think it's clear that it would be very very difficult for anyone in a real-world scenario like this to say that Corona's tonemapping needs to be reworked from scratch because Fstorm produces incredibly more photographic images.
I simply don't believe that is true. I can tweak my contrast and color settings to make the images match a little better, but I wanted to see what a minimum workflow looks like, and if Fstorm is truly superior beyond a doubt.
I do believe that there is a very valid argument to be made about enabling LUT, highlight compression, and increasing contrast by default. Or make it a single button. Or in some way make it SUPER EASY to do, even by accident. My logic is that the pros would don't like it but know how and why to disable. And the rest of the world would enjoy much better images by default.
There is a different discussion, that only the top of the top of th professional users understand and really care about when you are pushing Corona to the limits you DO bump into the inherent limitations of the sRGB color space. But my guess is that 90 -95% of the time, when people complain about tonemapping, what ther are taliing about is what I'm showing in this experiment.
Another note. When a lot of people say something, even if you KNOW it is wrong, it is worth paying attention to. My guess is that because the experts know how to do what I'm showing intuitively and naturally, they dismiss conversations as nonesense. If there was only one or two people asking for "fstorm colors" then I would agree. But a LOT of people want that, maybe they don't know exactly what they want, but they want their images to look better.
So my hypothesis stands.
"fstorm colors" means 2 things.
1 is super complex, only a handful of people understand it and care about that. It requires a lot of work from the devs.
The other one is making certain settings, that are already there, more approachable, maybe the default.