POV-Ray: Newsgroups: povray.beta-test: image

POV-Ray : Newsgroups : povray.beta-test : image_pattern		Server Time 30 Jul 2024 10:21:15 EDT (-0400)

From: Vampyrium
Subject: image_pattern
Date: 2 Dec 2001 05:15:16
Message: <3c09ff34@news.povray.org>

-Hail

  Some test renders show me that image_pattern produces unexpected results.
If a map is used with the full 8-bit range 0-255 (haven't checked 16-bits)
then the actual range in the map is not 0-255 (0-1 pov language), I found it
to be 76-255 (almost 0.3-1 pov language). I will post two images shortly in
the binaries section that display this. Test.png is a Photoshop generated
file with pixel values from 0-255, next is bugtest.png which is the
rendering done by pov and last is the source code of the scene.

P2-450, 64Mb, W2k.

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From: Thorsten Froehlich
Subject: Re: image_pattern
Date: 2 Dec 2001 07:52:25
Message: <3c0a2409@news.povray.org>

In article <3c09ff34@news.povray.org> , "Vampyrium" <cyb### [at] hotmailcom>
wrote:

>   Some test renders show me that image_pattern produces unexpected results.
> If a map is used with the full 8-bit range 0-255 (haven't checked 16-bits)
> then the actual range in the map is not 0-255 (0-1 pov language), I found it
> to be 76-255 (almost 0.3-1 pov language). I will post two images shortly in
> the binaries section that display this. Test.png is a Photoshop generated
> file with pixel values from 0-255, next is bugtest.png which is the
> rendering done by pov and last is the source code of the scene.

Confirmed and fixed.  The code used an incorrect formula to turn a color
image into a grayscale image.  The workaround is to use a real grayscale
image rather than a color image with only gray colors.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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