Color Grading Using Lookup Tables

Neox

Hey everyone, i just read the cool tutorial on udn http://udn.epicgames.com/Three/ColorGrading.html
i never used postprocess volumes as we could do everythign we needed in an extra post process chain - so maybe i need to get a postprocess volume working and i'm just to stupid for that or is there a way to integrate that into a PPchain?
I didn't find the option in the uberpostprocess node, i can find it in the postprocess volume and world settings but as we use custom postprocesschain is there any way to apply this to the scene?

JordanW

I -think- the LUT has to be applied in the world or volume,

Neox

both don't seem to work here, and i'm wondering if using the custom made postprocess chain is producing it or not hmmm

gamedev

You can specify your default post-process chain in an ini or per level in the world info properties.

As for the LUT, you can also specify this in world info. One gotcha though, you need to ensure your custom post-process chain has the 'Enable HRDToneMapper' flag checked on under the UberPostProcessEffect properties. Without that flag, your LUT won't work.

Hope that helps!

-Tyler

Neox

nope

the postprocesschain is defined in the defaultengine.ini so we can use our own as opposed to the standard chain. It is working i can do whatever i want inside that chain, turning on HDRTonemapper changes the look entirely but that normal we would have to fix the lighting and textures, however, neither the world info settings nor the settings inside a postprocess volume seem to apply, it just doesn't change a thing :S

MaD

Dunno just guessing, maybe you didn't turn on use world settings at the bottom in the uberpostprocess.

Maybe you could add an extra uberpostprocess effect turn on tone mapping and use world settings and just add a lut in the world properties so it doesn't mess up your other postprocess settings.

But it still is a pity that the neutral lut, you can find in the content browser isn't neutral at all (changes the scene completely). It would be a lot easier when that didn't have any effect on your scene at all.

Xoliul

Neutral LUT should be neutral, it's just that the Tonemapping, which is required for the LUT's to work, changes the scene. I tried to compensate it back into values like it used to be, by editing the LUT, but it's almost impossible to do so.

Neox

ok it was the combination of use world settings and the tone mapping, i think i before just applied one at a time and yeah - neutral is super different to what we had before with LDR, what would be the workflow to get back to it? How would we need to change the textures and the scene shadows, mids and highlights to get back to the usual look, before we can apply colorgrading?

JordanW

just disable HDR tonemapper to remove the contrast enhanced tonemapping. The HDR Tonemapper is intended to work with more HDR centric content where the textures are a bit milkier and the lights are brighter. Moving to it from existing levels/content requires some work.

Neox

but then color correction via LUTs won't work, right?
I know its going to be work, the question is, what would be the best workflow to tackle this - if it is too much we are going to stay with what we have, but i first need to know how many ressources we would need to get the colorcorrection to work.

JordanW

I dont think LUT and HDR tonemapper are tied together, we just happened to add them at the same time.

Best workflow would be to neutralize most textures first, make sure they're not too dark, we already did this with our own content when switching to Lightmass.

Then you would mostly relight the levels with brighter values, ex: Sun would be like value of 5-10. You should also get rid of color adjustments using the 9 numbers in the PP volume/world and instead do it through the LUT.

Neox

hm then it must be a bug as i cannot use the "Color Grading_Lookup Table" when "Enable HDRTonemapper" is turned off :S

Xoliul

It even says so somewhere (forgot where, but I definitely read that), the Tonemapper is required for LUT's.

JordanW

ah my bad