Author Topic: BUG? Why do I have to put an inverse gamma on my linear textures?  (Read 8066 times)

2018-10-18, 16:31:24
Reply #15

JPeters

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Here is the scene, as promised and a render.

Cube 1 - 0.55 Glos
Cube 2 - CRN 55% grey
Cube 3 - MARI 55% grey
Cube 4 - MARI 55% grey - Inverse Gamma


2018-10-19, 19:33:21
Reply #16

burnin

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Thank you for taking the time to present your issue in simple & readable manner.
Well, it looks like MARI works this way:
So what you observe, is correct behavior & with that in mind, results are consistent all over, in other apps and engines (although a few adapt shaders automatically ie. Unity:
Quote
What the shader does for the albedo and specular is "linearize" the maps. It removes the gamma-encoded values from the map in the shader code by applying an inverse gamma to it of 0.4545. In the Unity workflow, this is done automatically and you don't need to flag the images as sRGB.
My conclusion is - It's nothing wrong with Corona (except the need to do this automatically) - feature request! ;)
eg. CentiLeo settings for comparison:


2018-10-22, 08:57:56
Reply #17

JPeters

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Thank you for taking the time to present your issue in simple & readable manner.
Well, it looks like MARI works this way:
So what you observe, is correct behavior & with that in mind, results are consistent all over, in other apps and engines (although a few adapt shaders automatically ie. Unity:
Quote
What the shader does for the albedo and specular is "linearize" the maps. It removes the gamma-encoded values from the map in the shader code by applying an inverse gamma to it of 0.4545. In the Unity workflow, this is done automatically and you don't need to flag the images as sRGB.
My conclusion is - It's nothing wrong with Corona (except the need to do this automatically) - feature request! ;)
eg. CentiLeo settings for comparison:

Thanks for looking into this.

It sort of makes sense but at the same time it doesn't. Why does Corona linearize the COL/SPEC COL maps but not any of the others when the embedded profile/setting is set to linear? That is just weird if you ask me, certainly since any other render engine I've worked with (Vray / Mental Ray / Clarisse) does do this properly.

2018-10-22, 16:57:55
Reply #18

burnin

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Values are not colors, therefor don't get the auto color correction treatment.
What does machine know? Nothing. ;)

2018-10-30, 10:11:34
Reply #19

JPeters

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Well, since they are driven by an RGB map they are clearly colors and should therefore be treated as such right?

2018-10-30, 22:49:45
Reply #20

burnin

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Well, since they are driven by an RGB map they are clearly colors and should therefore be treated as such right?
Basically (LWF management)... How right has left the building. ;)
« Last Edit: 2018-10-30, 23:00:09 by burnin »

2018-10-31, 09:08:28
Reply #21

JPeters

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Thanks for that article :)

That being said, it's still weird that I have to apply an inverse gamma to an already linear image for it to work as a value.

2018-10-31, 18:22:04
Reply #22

burnin

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