WMS using ecw file

[Gareth Heinz]

Thanks for the response, the output options you give are the ones I have 
used in the WMS for the ecw image, the results for which you can see from 
using the following urls in any WMS 1.1.1 compliant viewer:

PNG output, very large file size but high quality:
http://203.202.1.211/pngwms.asp?SERVICE=WMS&VERSION=1.1.1&REQUEST=getcapabilities

JPEG output, small file size but very low quality:
http://203.202.1.211/jpgwms.asp?SERVICE=WMS&VERSION=1.1.1&REQUEST=getcapabilities

What I do not understand is why (when using the same ecw image) does the 
JPEG output give very good quality results and a small filesize using a CGI 
call, but such poor results in a WMS which uses exactly the same output 
options?

Any advice most welcome,
Gareth

----- Original Message ----- 
From: "Jacolin Yves" <yjacolin at FREE.FR>
To: <MAPSERVER-USERS at LISTS.UMN.EDU>
Sent: Wednesday, August 30, 2006 11:21 PM
Subject: Re: [UMN_MAPSERVER-USERS] WMS using ecw file


Le Mardi 29 Août 2006 15:31, Gareth Heinz a écrit :
> Hi all,
>
> Serving a satellite image ECW (approx 4GB file) as a MapServer CGI
> consumable. While a 24bit PNG looks great, the filesize can be quite huge,
> therefore I've modified to serve it as a JPEG with QUALITY set to 100. 
> This
> still looks good and gives a very small filesize compared to the PNG.
>
> Now here is the main question, when serving the same layer as a WMS
> service, the JPG looks really washed-out, where as the PNG while looking
> great has too big a filesize for the end-users. So I was wondering if 
> there
> was a bug with Mapserver or GDAL (as I take it MapServer uses GDAL to 
> serve
> ECW's), or if anyone out there has a solution?
>
> Using MapServer 4.8.3 on Windows 2003 serving via IIS.
>
> TiA.
> Gareth
To improve your output you have several ways. Some of them got some 
contrains.
I use ECW and try output in png (big but not good) and jpg not so good. Some
others parameters for both jpeg and png not output a good images.
Here my output format for PNG :
  OUTPUTFORMAT
    NAME png
    DRIVER "GD/PNG"
    MIMETYPE "image/png"
    IMAGEMODE RGBA
    EXTENSION "png"
    FORMATOPTION "INTERLACE=OFF"
    TRANSPARENT OFF
  END

For jpeg :
  OUTPUTFORMAT
    NAME jpeg
    DRIVER "GD/JPEG"
    MIMETYPE "image/jpeg"
    IMAGEMODE RGB
    EXTENSION "jpg"
    FORMATOPTION "INTERLACE=OFF"
    FORMATOPTION "QUALITY=100"
  END
You can change QUALITY parameter.

Hope it will help to improve your output.

Regards,

Y.
-- 
Yves Jacolin
http://yjacolin.gloobe.org
----
Stagiaire Conservatoire Régional des Espaces Naturels de la région Centre
http://cahiersnaturalistes.free.fr/cpnrc/
----
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puisque je suis de bonne foi?
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