POV-Ray: Newsgroups: povray.general: Filtered Image Maps

POV-Ray : Newsgroups : povray.general : Filtered Image Maps		Server Time 15 Nov 2024 01:15:20 EST (-0500)

From: Alexander Fried
Subject: Filtered Image Maps
Date: 1 Apr 1999 11:47:49
Message: <3703B12A.FD1C216A@jk.uni-linz.ac.at>

I am trying to project am image onto a wall. My scene consists of one
plane a screen, a light source and a second plane between the light and
the screen holding the image: 

------------- screen 
  \       / 
 -----------  image 
    \   / 
     \ / 
      o       light 

I am using a png image. Each pixel has an alpha value of 128. POV uses
this alpha a transmit and therefore only gray shadow is visible. The
"filter all" keyword crashes on 3.1e (Windows) and 3.0 ignores it. The
only way I found, is using gif, but I don't want to reduce the color.
The best solution would be to tell POV it should use the alpha channel
as filter. Does anyone know if this is possible or is there another way
to do it?

Thanks, 

Alex

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From: Nathan Kopp
Subject: Re: Filtered Image Maps
Date: 1 Apr 1999 23:43:07
Message: <37044A39.4D0298C@Kopp.com>

I don't think what your asking for is possible directly, but you could use
another lossless image format (such as TGA), or remove the alpha value
from the PNG file and use filter all 0.5.

-Nathan

Alexander Fried wrote:
> 
> I am trying to project am image onto a wall. My scene consists of one
> plane a screen, a light source and a second plane between the light and
> the screen holding the image:
> 
> ------------- screen
>   \       /
>  -----------  image
>     \   /
>      \ /
>       o       light
> 
> I am using a png image. Each pixel has an alpha value of 128. POV uses
> this alpha a transmit and therefore only gray shadow is visible. The
> "filter all" keyword crashes on 3.1e (Windows) and 3.0 ignores it. The
> only way I found, is using gif, but I don't want to reduce the color.
> The best solution would be to tell POV it should use the alpha channel
> as filter. Does anyone know if this is possible or is there another way
> to do it?
> 
> Thanks,
> 
> Alex

Post a reply to this message

From: Alexander Fried
Subject: Re: Filtered Image Maps
Date: 3 Apr 1999 04:12:15
Message: <3705E95F.249529F1@jk.uni-linz.ac.at>

It seems that filter all 0.5 doesn't work with 24 bit/pixel. The
statement was ignored using TGA and POV crashed using PNG (with and
without alpha channel).

Alex

Nathan Kopp wrote:
> 
> I don't think what your asking for is possible directly, but you could use
> another lossless image format (such as TGA), or remove the alpha value
> from the PNG file and use filter all 0.5.
> 
> -Nathan
>

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