[mapserver-users] display nice tiff renderings

[Richard Greenwood]

Going to ECW will not help and will actually make it worse. ECW provides a 
24bit color image to GDAL (even for garyscale!) which is then down sampled 
by GDAL. I'm not sure what you mean by poor image quality. Are you 
referring to color quality? And are you using a tile index or a single 
image. If you are using a tile index (using multiple images) make sure they 
all use the same 8bit color palette, and of course make sure the palette is 
well chosen in the first place. I use an 8bit color palette of just 200 
colors, which leaves 50+ "spare" colors for other map layers. I created the 
palette in Photoshop by sampling about 5% of my images and then applied the 
palette to all of the images.

Rich

At 01:16 PM 7/17/2002 +0800, you wrote:
>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


Richard W. Greenwood, PLS
Greenwood Mapping, Inc.
Rich at GreenwoodMap.com
(307) 733-0203
http://www.GreenwoodMap.com