ACES color lut and TG renders.

[gregtee]

Interesting test using ACES, or Academy Color Encoding Specification 3D lut to grade a couple of Terragen renders.  You can read up on the specifics here:  http://icolorist.com/wp-content/uploads/2012/04/ACES_Nucoda-r1_web1.pdf

In nutshell what the lut does in remap all your colors in a manner that allows your monitor to correctly display all the colors generated by render.  Since many colors and values rendered in TG routinely exceed a value of 1, imagery gets "clipped" on these high ends, resulting in renders that look like they were shot with a camcorder rather than film, which has a better response curve.  This lut  remaps the entire color space of the image to match the response curve of film, allowing all pixel values to rest in the color gamut of your monitor.  The result is a more photographic representation of your renders. 

I've attached two renders I did in TG, each with and without the LUT applied.  See if you can tell the difference between the two.  The main difference is preservation of highlight detail in the ACES applied image, as well as a drop in the gamma which makes the shadow areas of the frame appear richer.

here's a raw TG render with only a slight gamma adjust:[attach=1]

And here's the same image with the ACES lut applied:  [attach=2]

Notice the image is richer and cloud the highlight details remain intact.  Also look at the highlight detail on the rocks.  The clipping effects are gone.

Here's another example: 

Raw TG render with slight gamma adjustment:  [attach=3]

And now with ACES applied:  [attach=4]

Highlights on the fronds don't clip anymore and overall saturation values are better too. 

Normally this type of thing would be used for files shot with digital cameras such as the Red, Alexa, or Sony cams but it seems to work well for rendered imagery as well. 

[TheBadger]

That is quite a difference. I did not read the paper. Is there consumer soft for this or is it proprietary?

[Tangled-Universe]

Seems to me ACES is a new/other colourspace definition with extreme wide gamut.
Greg, your explanation of remapping values to "fit" to your screen looks a bit odd to me. The clipping you mention is just high dynamic range I'd tend to say.
Also I'd tend to just say that the ACES colourspace definition maps colours "differently", like having linear colour is different from non-linear or log colour space.
This can offer advantages for grading.
Eventually all existing colour profiles are designed to represent as many colours as possible within the current specification of monitor colour profiles or any medium.
In the end, you still need a good monitor to accurately represent colour.

This may seem I'm skeptic here, but I'm not

I really like how it works with the first render!
The second render is pretty obvious to0, but the outcome isn't really to my taste...something in between may look nicer, but perhaps it's just more accurate.
(Like shooting a photo with your dSLR along with a calibrator cube or card. Once applying the calibration using those objects the image is just dead accurate, but not neccesarily more beautiful (often rather not).)

Cheers,
Martin

[gregtee]

I guess one of the advantages of working where I do is we all get Dreamcolor IPS panels to work on that get calibrated on a regular basis.  But you're right in any case, the LUT is designed to remap colors that would normally get clipped out of the display's ability to display back into its display capability.  Even our Dreamcolors can't display these higher values without clipping. 

On that note I've heard of a new display made by Dolby that's not available for commercial use yet (it's a prototype) that can display colors significantly over 1 in value.  It uses an incredible amount of electricity to run, something like the equivalent of 3 houses, but it puts out light levels and ranges that mimic daylight. 

[TheBadger]

It uses an incredible amount of electricity to run, something like the equivalent of 3 houses, but it puts out light levels and ranges that mimic daylight.

Now we are in mad scientist territory.

...but not neccesarily more beautiful (often rather not).)

This and the rest of what you wrote made me think about the issues with tone mapping. When tone mapping you can get the blacks in the improved images in the OP very easily. But often is the case that color becomes absurd. IT would be nice to have something that could be used after tone mapping, that brings the color back to real world, but still lets you use the dynamic range so easily. Even if the colors of reality are not ideal/beautiful, getting them back to reality would be a better place to start from when color grading/editing, than the colors I often get after tone mapping.