[mapserver-users] display nice tiff renderings

[Ed McNierney]

Nyon -

Are you displaying the final GeoTIFF image in its "native" resolution?  That is, are you using a scale in which one pixel in the output image corresponds to one pixel in the input image?  If not, that will degrade image quality.  MapServer uses very simple linear sampling to zoom in or out on a source image, because it's fast.  Other methods give better images but are quite a lot slower.

Can you view the GeoTIFF image in an image viewer or graphics application first?  That way you can determine whether the image quality is good going INTO MapServer or whether the degradation of the image is happening before that step.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242 

-----Original Message-----
From: YC Nyon [mailto:ycnyon at pd.jaring.my]
Sent: Wednesday, July 17, 2002 1:16 AM
To: mapserver-users at lists.gis.umn.edu
Subject: [mapserver-users] display nice tiff renderings


this is a continuation what happening since i posted a similiar question few
weeks back.

1. Process the landsat image in Erdas
2. Export it as Geotiff (24-bit)
3. downgrade it to geotiff-8bit in Macromedia Fireworks. (i found out from
the list that MS doesn't do a good job of the 24 to 8 bit tiff conversion)
4. now displays as a geotiff in MS

the quality still looks poor. i thought maybe i can
1. display it as a Erdas lan format. however, i think it's only for 1 band.
2. export it as ErMapper ECW format. would that yield better quality?

Thanks
Nyon