I need the ability to be able to display ECW and JPEG2000 format files within MapServer via a Community Mapbuilder client which sends WMS requests for the images to MapServer

[John Mitchell]

Frank,

The ECW is already in a compressed format, so this means that the image is
compressed another 95%?  This additional compression is for performance
purposes?; does it affect the image quality?

Thanks,

John

On 11/30/06, Frank Warmerdam <warmerdam at pobox.com> wrote:
>
> John Mitchell wrote:
> > Hi Frank,
> >
> > I now able to display ECW type files via mapserver within a community
> > mapbuilder web browser client.  I had question on part of the sample map
> > file that you sent:
> > OUTPUTFORMAT
> >  NAME jpeg2000
> >  DRIVER "GDAL/JP2ECW"
> >  MIMETYPE "image/jpeg2000"
> >  FORMATOPTION "TARGET=95"
> >  IMAGEMODE RGB
> > END
> >
> > What does TARGET=95 mean?
>
> John,
>
> This means that I am requesting 95% reduction in image size during
> compression - ie. 20:1 compression.
>
> > I am having good success (as far as image quality and small size
> > downloaded to the browser) with displaying my image data as jpeg within
> > community mapbuilder as an example
> >       <FormatList>
> >         <Format current="1">image/jpeg</Format>
> >       </FormatList>
> > But when I try displaying it as a png as an example.  I get poor quality
> > as far as the color.
> >       <FormatList>
> >         <Format current="1">image/png</Format>
> >       </FormatList>
>
> You like want PNG24 format.  The plain PNG format results in a reduction
> to 8bit which causes a lot of damage to the image.  The predefined 24bit
> PNG output format is called "PNG24", and has a mimetype of
> "image/png; mode=24bit"
>
> > What application do you use to create your .ECW files?
>
> The original ecw file I was serving from was one I downloaded from
> geotorrent.org.  But I do sometimes use gdal_translate to produce
> ecw files.
>
> Best regards,
> --
>
> ---------------------------------------+--------------------------------------
> I set the clouds in motion - turn up   | Frank Warmerdam,
> warmerdam at pobox.com
> light and sound - activate the windows | http://pobox.com/~warmerdam
> and watch the world go round - Rush    | President OSGeo, http://osgeo.org
>
>


-- 
John J. Mitchell
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