POV-Ray : Newsgroups : povray.binaries.images : Using "transmit all" with an image map : Re: Using "transmit all" with an image map Server Time
4 Feb 2023 01:48:29 EST (-0500)
  Re: Using "transmit all" with an image map  
From: Dave Blandston
Date: 31 Dec 2022 20:05:00
Message: <web.63b0db60eaa53b9ca65171949334df62@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> So, I don't know where you're experiencing problems, since my little test scene
> with a transparent background png I grabbed from the web seems to work fine.
>
> Perhaps you have some complicating factor in your scene, or maybe some
> strange/incorrect syntax/structure to your image_map statement.
>
> (I'm still battling with the finer points of cutaway_textures....)



This issue may be what the statement "New as of version 3.8, using filter all
and transmit all on an image file with an alpha channel is now supported
properly (requires #version 3.8 or higher)" is referring to in the new
documentation. I haven't upgraded yet.

That being said, if you're interested in making sure that alpha channels are
working properly in version 3.8, use a color other than white for the
background. As you can see from the sample image I posted, the RGB components of
transparent pixels do alter the final image. This effect isn't visible with a
white background. The RGB components of the transparent pixels could be <255,
255, 255>, <0, 0, 0>, or they could be the unchanged remains of a photo, or they
could be random I suppose. Version 3.7 produces varying results based on these
different conditions - see the attached image.


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