POV-Ray : Newsgroups : povray.unofficial.patches : curves post process input clipped (mp0.7) Server Time
20 Jul 2024 19:16:25 EDT (-0400)
  curves post process input clipped (mp0.7) (Message 1 to 4 of 4)  
From: Kari Kivisalo
Subject: curves post process input clipped (mp0.7)
Date: 31 May 2001 00:09:06
Message: <3B15C461.7256CCA8@x.x>
post_process {
  curves {
    all
    spline {
      linear_spline
      0,0
      10,1
    }

This should linearly compress input range 0-10 to 0-1 but max output
is at 0.1. I remember post process stage used unclipped floats but
seem like it's not the case.

_____________
Kari Kivisalo


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From: Kari Kivisalo
Subject: Re: curves post process input clipped (mp0.7)
Date: 31 May 2001 00:56:17
Message: <3B15CF70.38284A28@x.x>
Also found out: curves input uses integer, gamma correction is applied
before curves. I tried to do some compression experiments but as such
curves can't be used because of clipping and bit resolution. Misplaced
gamma correction isn't a problem because it can be turned off and applied
to the file.


_____________
Kari Kivisalo


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From: Chris Huff
Subject: Re: curves post process input clipped (mp0.7)
Date: 31 May 2001 12:23:52
Message: <chrishuff-6E73C1.11205231052001@povray.org>
In article <3B15C461.7256CCA8@x.x>, Kari Kivisalo <x@x.x> wrote:

> I remember post process stage used unclipped floats but seem like 
> it's not the case.

The post-processed image starts with clipped colors, you need to use the 
raw_image post_process to get the unclipped colors before using the 
curves filter.

-- 
Christopher James Huff - chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><


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From: Chris Huff
Subject: Re: curves post process input clipped (mp0.7)
Date: 31 May 2001 12:29:45
Message: <chrishuff-6E2B7E.11264631052001@povray.org>
In article <3B15CF70.38284A28@x.x>, Kari Kivisalo <x@x.x> wrote:

> Also found out: curves input uses integer,

Um, no it doesn't.


> gamma correction is applied before curves.

Gamma correction is done separately from post-processing...but it should 
probably be done afterwards, it might be considered a bug. A gamma 
correction of 1 won't do anything, though...so you could do it with 
post-process filters instead.

-- 
Christopher James Huff - chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><


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