Toy can try  to split the raster data out into a tiled base layer, which uses 
JPEG format. Then use PNG8 format for the vector data (either tiled base layer 
or dynamic).

This would move most color variation to the JPEGs, which would then free the 
PNG8 color table generation to work with a much smaller color map and thus do a 
better job at preserving the antialiasing shades.

Traian

P.S. I am not sure if it is possible to have JPEG base layers though...



From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Gary Morin
Sent: Thursday, March 20, 2008 5:58 AM
To: [email protected]
Subject: [mapguide-users] Render services image formats

Hi

I've been investigating the render services image formats in an attempt to 
improve performance over the internet

My first observation, it appears in MGOS 2 setting the image format in 
serverconfig.ini does not affect the formats being served, it was only when I 
edited the ajaxmappane.templ did I see a difference.

I know the default is PNG, but we can change it JPG and with MGOS2 PNG8.

The problem is, with PNG the map images look great, but the download size is 
enormous, I'm using some raster maps and the downloads are in the region of 
1.5mb. on my internet connection it is taking in the region of 6 seconds to 
display the map after a pan.

If I switch to JPG the download is much faster, the downloaded images are 
around 250K, but the quality is poor, some text and labels are now unreadable.

I have also tried the new PNG8 format, but its results were very similar to 
JPG, image quality is poor.

Many of my clients are use to working with the old MG 6.5, even with raster 
files being served it performance was great.

Is there a way to alter the compression ratio of a format or any plans to allow 
this to be done in the future?

Thanks

Gary






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