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 <[EMAIL PROTECTED]> 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, [EMAIL PROTECTED] 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
