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14 Aug 2024 18:00:18 EDT (-0400)
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From: Kari Kivisalo
Subject: Film exposure simulation patch
Date: 9 Nov 2002 11:04:59
Message: <3DCD3221.F40A6CBA@luxlab.com>
The patch simulates decrease of reactive chemicals in film
emulsion during exposure. The areas that have received more
light react less than other areas. Usefull for high contrast
scenes as it brings up the dark areas and limit bright areas.

I have combined aperture, film speed, and exposure time into
one exposure variable which goes into global_settings. The images
show the difference between normal and exposed image. I'll test
it some more to see if it works nicely with anti-aliasing and
focal blur.


_____________
Kari Kivisalo


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Attachments:
Download 'exposure.jpg' (39 KB)

Preview of image 'exposure.jpg'
exposure.jpg


 

From: Rick [Kitty5]
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 12:31:53
Message: <3dcd4689@news.povray.org>
Can we have a few more demos scenes - I for one fond this very interesting!

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Rick

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From: Txemi Jendrix
Subject: RE: Film exposure simulation patch
Date: 9 Nov 2002 12:40:57
Message: <3dcd48a9@news.povray.org>

3DCD3221.F40A6CBA@luxlab.com...
> The patch simulates decrease of reactive chemicals in film
> emulsion during exposure. The areas that have received more
> light react less than other areas. Usefull for high contrast
> scenes as it brings up the dark areas and limit bright areas.

Very interesting and useful patch. Looks great.
Waiting to see more examples

Txemi Jendrix
http://www.txemijendrix.com


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From: Hugo
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 14:18:39
Message: <3dcd5f8f$1@news.povray.org>
That sounds great. What about digi-cams? Are they inferior in this field?

Regards,
Hugo


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From: Johannes Dahlstrom
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 14:32:32
Message: <3dcd62d0@news.povray.org>
Kari Kivisalo wrote:

> 
> The patch simulates decrease of reactive chemicals in film
> emulsion during exposure. The areas that have received more
> light react less than other areas. Usefull for high contrast
> scenes as it brings up the dark areas and limit bright areas.

Heh, I made a patch just similar to yours a couple months ago... My first 
Povray modification :) You're using the 1-exp(-x) function, right?


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From: Kari Kivisalo
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 15:36:58
Message: <3DCD71E8.B1D36A7C@luxlab.com>
Johannes Dahlstrom wrote:
>
> Heh, I made a patch just similar to yours a couple months ago...

And you kept in the desk drawer?


> You're using the 1-exp(-x) function, right?

It seems to be the simplest usable function for this purpose.


 
_____________
Kari Kivisalo


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From: Kari Kivisalo
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 15:48:15
Message: <3DCD748D.F97958E4@luxlab.com>
Hugo wrote:
> 
> What about digi-cams? Are they inferior in this field?

It seems that camera manufacturers aren't forthcoming about
the on-board image processing features. One transfer curve
I saw was definitely film-like which is kind of natural :)


_____________
Kari Kivisalo


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From: Johannes Dahlstrom
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 16:03:04
Message: <3dcd7808@news.povray.org>
Kari Kivisalo wrote:


> And you kept in the desk drawer?
> 

I was quite fond of it and was of course going to publish it here, but then 
Kevin Loney came up with his own patch just before I was about to do so.


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From: Kari Kivisalo
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 16:36:29
Message: <3DCD7FD9.ABC1C618@luxlab.com>
Johannes Dahlstrom wrote:
>
> I was quite fond of it and was of course going to publish it here, but
> then Kevin Loney came up with his own patch just before I was about to
> do so.

His patch was going in different direction so I decided to make
this one.


_____________
Kari Kivisalo


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From: Christopher James Huff
Subject: Re: Film exposure simulation patch
Date: 9 Nov 2002 19:32:13
Message: <chrishuff-667AA3.19315309112002@netplex.aussie.org>
In article <3dcd5f8f$1@news.povray.org>, "Hugo" <hua### [at] post3teledk> 
wrote:

> That sounds great. What about digi-cams? Are they inferior in this field?

Not really sure what you are asking...the CCD will have a different 
response curve than film or the human eye. Some of them might do 
filtering to end up with something closer to film, or just something 
that looks better. The design of the CCD element probably matters as 
well.
They can't really be inferior or superior to POV, since they have quite 
different information. POV has essentially unbounded float triples with 
the "real" light intensities, cameras have fixed point values with the 
raw output of CCD elements, restricted to a certain range.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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