Thanks Armin, That's interesting, and after looking at the documentation (http://mapserver.gis.umn.edu/docs/howto/raster_data/#special-processing-dir ectives) I have a fuller understanding of the capabilities.
My still outstanding question is in regards to the layer processing tags and the images in a TILEINDEX. Do each of the images get preprocessed before the composite is made? Or is the composite made then the processing applied? Anyone have any thoughts on this? If not I'll let you know. Randy -----Original Message----- From: Armin Burger [mailto:[EMAIL PROTECTED] Sent: Monday, January 30, 2006 1:07 PM To: Randy How Cc: [email protected] Subject: Re: [UMN_MAPSERVER-USERS] Raster JPEG Input using OFFSITE Randy, with JPEG (and mainly also ECW) you will not completely get rid of the black borders because, as you mention, their 'black' is not fully black. But you can get get most parts of the black transparent by applying a PROCESSING "SCALE..." tag, eg. PROCESSING "SCALE_1=3,255" PROCESSING "SCALE_2=3,255" PROCESSING "SCALE_3=3,255" OFFSITE 0 0 0 All pixel values from 0 to 3 will be mapped to 0 and then set transparent by the OFFSITE tag. It has the slight drawback that some very dark parts inside the image will also be touched by this and become transparent. It works quite well though for multispectral images, a bit less nicely on panchromatic. Armin Randy How wrote: > My question is in regards to using the OFFSITE setting for a JPEG data > source to remove the "black/NoData" areas. Does it work at all? I've > attempted this but it made no difference (mapserver 4.7). > > It will work with Tiff's (that have internal JPEG compression) and > poorly with ECW's due to the variability in "black". > > Randy
