[Tilecache] Where in TC code is metatile cutting?

[Ivan Mincik]

> Ivan,
>
> Using PythonMagick, I was able to create the following image:
>
> http://img35.imageshack.us/img35/6583/testyi.png
>
> using this code:
>
> import PythonMagick
> import urllib
>
> data = urllib.urlopen("http://gista.sk/dl/test.png")
> blob = PythonMagick.Blob(data.read())
> image = PythonMagick.Image(blob);
> image.quantizeColors(256)
> image.quantizeDither(False)
> image.quantize()
> image.write("/tmp/test.png")
>
> PythonMagick can be somewhat difficult to unstall, although it was
> trivial on Ubuntu server as a package already exists for it.

Thanks a lot for this example. 
I seems that original quantized image from UMN Mapserver is loaded by ImageMagick to some internal structure and than it 
can be processed (cut metaTiles to tiles, ...). If I want to save it to same format as it was produced by UMN Mapserver 
I need to use quantize again in ImageMagick. Resulting palette is totally different to original so UMN Mapserver 
quantization is lost/replaced by ImageMagick and therefore is not needed - I rather can produce RGBA images from UMN 
Mapserver to save CPU.

Still, we don't have a solution for cutting quantized metaTiles in python and saving them back without any changes to 
palette. 

> You appear to have better results with MapServer and indexed RGB
> output.  I was never able to get the fonts looking good, hence the
> post-processing to reduce the color depth with ImageMagick.  Can you
> share your OUTPUTFORMAT section of your map file?

My outputformat section. Using UMN Mapserver 5.2.x

	OUTPUTFORMAT
    		NAME "PNG_AGGAQ"
    		DRIVER "AGG/PNG"
    		MIMETYPE "image/png"
		IMAGEMODE RGBA
   		FORMATOPTION "QUANTIZE_FORCE=ON"
    		FORMATOPTION "QUANTIZE_DITHER=OFF"
    		FORMATOPTION "QUANTIZE_COLORS=256"
		FORMATOPTION  "INTERLACE=OFF"
		EXTENSION "png"
	END

Ivan
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