[Mapserver-users] JPEG and IMAGETYPE with mapserver 3.6.3

[Frank Warmerdam]

fx gamoy wrote:
> hello
>  
> i have tested the property IMAGEQUALITY with jpeg output and i can't see 
> any difference between two extrems values of this property.
> i have also tried to force it using mapscript $map->set(imagequality,25) 
> and $map->set(imagequality,100)  and the output file (jpeg) is the same.
> is it a known bug?

Hi,

There are a few issues here.  In response to your email I investigated the
handling of the IMAGEQUALITY keyword in MapServer 3.7.  It turns out setting
the IMAGEQUALITY keyword was *not* having the desired effect.  I have fixed
this - for static map files.

However, there is also the issues that the preferred way of setting your
jpeg image quality in 3.7 is to set a FORMATOPTION "QUALITY=n" line in the
OUTPUTFORMAT declaration you are using.

eg.
OUTPUTFORMAT
   NAME jpeg24
   DRIVER "GD/JPEG"
   IMAGEMODE RGB
   TRANSPARENT OFF
   FORMATOPTION "QUALITY=25"
END

Internally the working output format has the image quality set if the
IMAGEQUALITY keyword is found in the map file, but I am not convinced that
the same logic will take effect if you dynamically change the image quality
value in a map from MapScript.  If possible, I would suggest you manipulate
the format options for the OUTPUTFORMAT directly.

I would give more detail but I don't use any of the MapScript environments
currently so it is hard for me to test how things work for them.

Best regards,

-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent