Chaos Corona for 3ds Max > [Max] Tutorials & Guides
OFFICIAL Q/A: sRGB, gamma, color pickers, linear workflow, ...
astudio:
Ok. 1 & 2 is clear. We need load it with gamma 1.0.
I prepared texture in photoshop with 25, 50, 75% and 100% brightness. With override 1.0 it works correctly, with automatic loading (2.2) - not. Png 8 and 16 bits - the same.
I attach it for proof :).
3. I converted this texture in 32 Bit, saved it as hdr. Here Juraj wrote: "For full quality disp, use the .exr file, loaded with gamma 1.0 of course. Not rocket science is going on."
I tested it - gamma 1 (or automatic, doesn't matter) gives me the same result as jpg with gamma 2.2. For correct result I need to load it with inversed gamma 0.454545.
What do I miss? How to store image in 32 Bit?
PS. BTW tiff is not working at all. Good to know.
astudio:
Friends, don't leave this thread. It's really important.
What will be conclusion about 32 bit textures? Do I need to override gamma 0.4545? (the test is in previous post)
romullus:
Can you describe how you created/saved exr texture in photoshop? I don't think that PS is best tool for authoring textures in 32 bit depth though.
Edit: i tried to create similar map like in post #10 in photoshop in 16bit mode, then converted image to 32bit and noticed how pixel values get changed after that, probably that means that photoshop has baked gamma during conversion (BTW, it tries to do so when converting from 32bits to lower depth too). After i corrected pixel values manually and resaved it as exr, then it works as displacement map as expected. So likely it's issue with photoshop and not with Corona or exr.
astudio:
You are right. There are bad news. Photoshop really change RGB at converting to 32 Bit. So what to do? Is PNG 16Bit enough for displacement? Is it better then jpg or it's the same? Or may be there is some special way for converting to 32 Bit?
EDIT: Just some interesting tests in photoshop: Image converted to 32 Bit has same lightness value in Lab mode, but in RGB mode change RGB values completely. Applying gamma 2.2 makes RGB values closer to original values (not the same), but change completely lightness value in Lab mode. :(
dubcat:
From my experience Photoshop is having a hard time reading negative floating point values.
If you want to get 1:1 result from a displacement bake, you have to save it as 32 bit.
This way you will get negative and positive floating point values. Displacement strength becomes a multiplier and should be left at 1 to get 1:1 result.
Let's say you sculpt a hill that is 20cm high and a pit that is -20cm deep on a plane.
Save it as 32bit.
Apply this displacement map onto a new flat plane.
Leave displacement strength at 1.
This will give give you a hill that is 20cm high and a pit that is -20cm deep.
If you change displacement strength to 2.
The hill will become 40cm high and the pit will be -40cm deep.
This is the proper/accurate way to generate/use displacement maps.
My soul always die a little when I see 3D scan stores sell displacement as 16bit.
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