Comments on: Colorspaces in XSI

By: Mako

Mako — Thu, 27 Nov 2008 16:19:30 +0000

Hey Harry,

We just had lunch earlier today and I just realize now that I had read your explanations while I was doing my tests using the spheron camera.

Well done. I’d be happy to discuss even longer about all this with you one day.

By: Harry Bardak

Harry Bardak — Wed, 30 Jul 2008 16:27:16 +0000

Obviously with XSI 7 you don’t need to bother with theses shaders. But the concept stay the same.

By: harry bardak

harry bardak — Sat, 21 Jun 2008 10:06:03 +0000

Use a gamma 1/2.2 node instead and the simple_tone_mapping shader.
That would do the trick.

There is no point to change that now.

By: Gene Crucean

Gene Crucean — Wed, 04 Jun 2008 23:03:47 +0000

Hey Harry, have you updated the code on this?

By: Splin

Splin — Tue, 03 Jun 2008 14:24:02 +0000

The sRGB to LIN script seems not to be working in 6.5?

By: harry bardak

harry bardak — Wed, 28 May 2008 08:40:44 +0000

oh crap you are totally right. I have even put the correct formula in my explanation but not in the shader.
I am going to fix that.
thanks !

By: mac_apple

mac_apple — Wed, 09 Apr 2008 13:25:03 +0000

very go0d!! but alike photoshop I can do nice ..thankss

By: Jeromee

Jeromee — Wed, 26 Mar 2008 16:46:01 +0000

Hi Harry,

I still tend to differ on the formula implemented in your source file LIN_to_sRGB.cpp. As specified in IEC 61966-2-1, the “1.055″ must be outside the parenthesis, not inside. Otherwise the sRGB LIN conversions would not be bijective.

Let’s take the simple example of LIN=1.0 converted to sRGB. If we use your formula:

result->r = pow(Ci.r *1.055, 1/2.4)- 0.055;

then the result is 0.968.

If we use what I read from IEC 61966-2-1:

result->r = 1.055 * pow(Ci.r, 1/2.4)- 0.055;

then the result is 1.0 (and obviously the 0.055 is intended to exactly compensate the 1.055).

The error on output sRGB value is at most 3.2 %, so from a render standpoint it is not so perceptible.

Jeromee.

By: szadam

szadam — Sat, 22 Mar 2008 09:57:15 +0000

where can i find the lens shader? i mean i go to camera/lens shaders/ but i cant find that lin2srgb stuff
i installed the spdl, so what am i doing wrong?

By: Gilles Marcoult

Gilles Marcoult — Fri, 08 Feb 2008 16:30:02 +0000

Hi everyone, i would share whith you a publication oh this shaders for win 64.

Well, it’s a test for me because i’m not a programmer and it’s the first time for me to create a dll with a IDE.

I hope i dont make any mistakes.

So the archive is here:

http://www.kymeris.com/xtrn/data/sRGB_utils_x86_x64.zip

Enjoy and thank you to the author.