Re: Re: Framebuffer and Gamma

["Alan Jones" <skyphyr(at)gmail.com>]

Mitchell and Lanczos both multiple some samples by negative values. It seems that these values, once combined with the gamma changes are causing your artifacts.

I'm not sure what order the gamma and filtering are done in, but perhaps that's partially the reason. It also may be the results of applying a gamma function to a negative number and so order may not be relevant.

Cheers,

Alan.

On 6/7/06, Harry Bardak <hb_xsimailinglist(at)hotmail.com> wrote:

By disabling intensity clipping or going in Raw clip  you have different result which isn't what I am looking after.

I guess by activating it you go to a Linear result only. But well it s just speculation.


Harry Bardak
TD / Compositor.

Http://perso.wanadoo.fr/harry.bardak/
+33 6 76 63 35 54
+44 781 661 4147

-----------------------------------------------
> Date: Wed, 7 Jun 2006 09:38:13 -0400
> From: bmillerxsilist(at)gmail.com
> To: XSI(at)Softimage.COM
> Subject: Re: Framebuffer and Gamma
>
> Hi Harry,
> I think the artifact is due to Intensity Clipping. If you turn that feature off, the image renders correctly (for me, anyway..)
> Brett
> On 6/7/06, Harry Bardak <hb_xsimailinglist(at)hotmail.com> wrote:
> Hi everyone,
> After the read of Luc Eric's article on xsi-blog, I was experimenting different approach to understand the Linear color space.
> I am a bit stuck in my investigation because I met probably a bug in XSi.
> If you look to these image :
> http://perso.orange.fr/harry.bardak/img/Mr_bug_Gamma_1.jpg
> http://perso.orange.fr/harry.bardak/img/Mr_bug_Gamma_0455.jpg
> http://perso.orange.fr/harry.bardak/img/Mr_bug_Gamma_22.jpg
> When I change the gamma value on the active effects tab, I got this kind of spike.
> I guess it s a bug because it's appear only when you use mitchell or lanczos filter.
> Box, Triangle, Gauss aren't affected by that or maybe they are too soft to get theses sample.
> I don't think it's come from my computer but I'am using the last Intel dual core sytem. I don't have access to others computer so if someone can test this simple scene it would be great and we could report it as a bug to the support team.
> Harry Bardak
> TD / Compositor.
> Http://perso.wanadoo.fr/harry.bardak/
> +33 6 76 63 35 54
> +44 781 661 4147
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