Transparency in JPGs on windows

[Frank Warmerdam]

On 10/2/07, Gabe <gabe at agtrix.com> wrote:
> Hi
>
>
> We are running several instances of mapserver on Linux and Windows.
>
> I have some maps that display a tiled aerial photography layer and some
> other vector layers.  The vector layers are polygons displayed using a
> symbol with a transparent background.  While the photography is switched off
> the map is produced as a png and all works as expected.  However when the
> photography layer is on (and the image is produced as a jpg) the vector
> layers no longer have any transparency and use instead the map background
> colour.
>
> That happens on the windows boxes but not on the linux boxes.  The
> installations are as similar as possible and this effect has been consistent
> since about mapserver 4.8 (now using 4.10.2 and 5.0.0)
>
> Is there a fix for this ?

Gabe,

JPEG files do not support transparency so as long as the output
format is JPEG there is no way to return files with transparent areas.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent