Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: walter on 2013-02-04, 14:50:33

Title: CoronaMtl Gamma corrected color,
Post by: walter on 2013-02-04, 14:50:33
Hi,

My render Gamma are set-up to 2.2, with a standard Linear Worflow setup.

Gamma/LUT Correction enable
Gamma 2.2
Bitmap Files
Imput Gamma 2.2
Output Gamma 2.2

I plug a JPEG Bitmap to a CoronaMtl, in diffuse/color slot. The color is OK to my render.
I enter directly the same color value than the Bitmap, the color was washed-out.

I must add a Gamma Correction node with a Gamma to 0.455 to have the good color Tone.
It's normal ?

Thanks !

Walter

Title: Re: CoronaMtl Gamma corrected color,
Post by: Ludvik Koutny on 2013-02-04, 14:54:36
Do you have enabled affect material editor and affect color selectors?

(http://i.imgur.com/S6YGT.png)
Title: Re: CoronaMtl Gamma corrected color,
Post by: walter on 2013-02-04, 15:18:29
Yes, I have these settings.
Title: Re: CoronaMtl Gamma corrected color,
Post by: maru on 2013-02-04, 20:55:03

I enter directly the same color value than the Bitmap, the color was washed-out.


Where do you get this value from?
Title: Re: CoronaMtl Gamma corrected color,
Post by: walter on 2013-02-04, 22:02:24
I open my Bitmap in Photoshop, it seems that these textures are flat areas of color.
With the eyedropper tool of Photoshop, I report the values.
Title: Re: CoronaMtl Gamma corrected color,
Post by: maru on 2013-02-04, 22:31:03
I may be stupid when it comes to gamma, but:

if you open your textures in photoshop, then doesn't it mean that the colour you are picking is NOT gamma corrected while the bitmaps you load up in max ARE gamma corrected on the final render? (max applies gamma correction for gamma 2.2, photoshop does not, as it is not set to do such thing)
Title: Re: CoronaMtl Gamma corrected color,
Post by: lacilaci on 2013-02-05, 18:01:29
what exactly are you looking for?
Title: Re: CoronaMtl Gamma corrected color,
Post by: andreupuig on 2013-02-05, 19:05:11
Maybe walter is wishing to have the same "color" if he import a "solid color bitmap" or insert the RGB values.
The problem he is facing is the gamma correction from max
Title: Re: CoronaMtl Gamma corrected color,
Post by: tiagodmed on 2013-04-12, 23:15:38
See if you are related to your problem. If you are saving this render in 32 bit you will embedding gamma 2.2 on your image and this will let her "washed".
In this case it would be correct to use the Output gamma in 1.
If you are saving to 8 or 16 bit oh yes you should embed gamma.
If you already knew about that I'm sorry for being redundant.
Title: Re: CoronaMtl Gamma corrected color,
Post by: lmikkelb on 2013-04-25, 13:22:18
I was thinking the same thing as tiagodmed if you output 32bit full float (exr) and use a 2.2 gamma on the output settings you wil break the linear workflow , since you ar baking the 2.2 gamma in to the file.

Do anyone have issues with the passes in the exr files?When i read them in nuke they have baked inn 2.2 gamme and while others end up in linear ( 1.0)
Title: Re: CoronaMtl Gamma corrected color,
Post by: Ondra on 2013-06-03, 18:35:47
I looked into this, and the problem is that max correctly handles bitmaps, e.g. converts them to linear space when linear workflow is used, but color selectors get colormapped only in UI, and still return the same value with different gamma. The numerical value you pick in the UI and which is returned is already in linear space, and this means, that it is different from the value in bitmap you paint in photoshop, which is in the gamma-corrected value.

Tl;dr: when using linear workflow with "affect color selectors", you will always get the same color in the scene that is displayed in the swatch. Just its numerical value is different from photoshop, because photoshop displays the value in gamma-corrected color space and 3dsmax in linear colorspace.