Transparent Backgrounds in Microstation

[Stephan Pollard]

I have tried to import a couple of GIFs with with white pixels as backgrounds
into a Microstation design file selecting the transparent switch.

The Microstation Reference Guide says in regard to the transparent option,
"If on, the image's background -- defined as all pixels with the same color
as the upper left-most pixel -- is transparent." Since white is the color of
the upper left-most pixel I expected all crossing vectors and underlaying
rasters to appear in place of the white pixels. This isn't what happened
however.

In the case of one GIF which had a black frame in it -- the black became
transparent, not the white. In the case of the other GIF (a blue ball inside a
white background) nothing became transparent!

Has anyone else had this experience?

Stephan Pollard
s...@cast.uark.edu

[Ray Bentley]

Stephan Pollard <sp> wrote:
>I have tried to import a couple of GIFs with with white pixels as backgrounds
>into a Microstation design file selecting the transparent switch.
>

<Snip>

>In the case of one GIF which had a black frame in it -- the black became
>transparent, not the white. In the case of the other GIF (a blue ball inside a
>white background) nothing became transparent!
>

Stephan,

How are you importing the images? The upper left pixel algorithum is used for
texture maps in rendering, however if you are using the Raster reference file
capability, the transparency color must be selected explicitly.

Ray Bentley