[mapserver-users] Removing collars on raster images

[Espen Isaksen]

Hi!

This question has been asked in different ways before, but the threads
do not seem to give me the answers I need.

We have lots of TB of images with black collars(borders). We would
like to try out using Mapserver for serving these images, but we need
to have the black collars transparent. That is fine in Mapserver as
long at you use regular Tiff. However, because of the many TB of data
we need to compress this data and preferably tiff with jpeg
compression.

However, this compression creates edges between the collar and the
image where the image does not get transparent.

I am struggling to find a solution to this problem. Is ideas on how we
can avoid this problem? Is it for example possible to set a
transparency mask in the Tiff image which can be used by Mapserver?
Another solution would be if Mapserver could support setting an area
in an image transparent based on a polygon file.

Any help is appreciated.

Espen