Displaying Mapserver raster in ArcMap gives 256 colours

[Frank Warmerdam]

POWER Brendan wrote:
> I have installed ms4w on a windows box with GDAL, etc...  From here I
> created a sample map (mapfile below) sourcing data from ecw images.
> When I use the WMS service via an intranet, I get a full colour image
> through the GetMap &LAYER command, however, when using ArcMap, I only
> get a 256 colour image.  Is there something I am doing wrong?
> Any assistance would be appreciated.

Brendan,

It may be that ArcMap picks a different format to fetch.  You might
check the logs to see what FORMAT= option ArcMap is using.  I think
there are "standard outputformats" still offered even when you declare
your own output format(s) (though I'm not sure about that).

> NAME TestMap
> STATUS ON
> SIZE 640 480
> EXTENT 116 -24 120 -22
> UNITS METERS
> SHAPEPATH "d:\Zone_50"
> IMAGETYPE FCADIType
> OUTPUTFORMAT
>   NAME FCADIType
>   DRIVER "GDAL/jpeg"
>   MIMETYPE "image/jpeg"
>   IMAGEMODE RGB
>   EXTENSION "jpg"
>   FORMATOPTION "INTERLACE=OFF"
>   FORMATOPTION "QUALITY=100"
>   FORMATOPTION "OUTPUT_TYPE=RASTER"
> END

Note that JPEG with QUALITY=100 is substantially larger than with
QUALITY=95, but is not measurably better quality.  The libjpeg docs
discourage use of QUALITY over 95.  I recently corrected the GDAL docs
to address this, and to clarify that QUALITY=100 is *not* lossless.

What is OUTPUT_TYPE=RASTER supposed to do?

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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