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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Hi Seth,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">nice work!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">To your questions:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">PNG24/32: lossless, so no quality-parameter, just compression efficiency (comparable to ZIP-Compression; size
 vs. needed time) [FORMATOPTION “ZLEVEL=n”]<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">PNG8: also lossless compression, but with color-depth-reduction (quantization), if you have data with more
 than 256 colors – this can/will  be lossy; also holds transparency-information (look-up-table for defined colors can have rgba-values)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">JPEG: IMHO the optimum for base-layers because of it’s small size and good performance (at least, if the base
 layer is not optimized with reduced color – png8); optimum for aerial images and “noisy” data; quality can be controlled as show downwards…<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l1 level1 lfo2"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">GeoTIFF: good solution, if you’d like to use the wms as “download-service” – images then hold complete GeoTIFF-Header
 (was buggy with older mapserver/GDAL-versions, but seems OK for now)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Transparency can be controlled in different manners (in mapfile or in original data), at least these, please correct
 me:<o:p></o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Mapfile:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo4"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">LAYER-MASK (polygon-layer, outer area is transparent)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo4"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">LAYER-OFFSITE (mapfile-NoData-value)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Data-side:<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo4"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">NoData-value (e.g. GTIFF-Header)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo4"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Alpha/Transparency (e.g. GTIFF – per Pixel)<o:p></o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo4"><![if !supportLists]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><span style="mso-list:Ignore">-<span style="font:7.0pt "Times New Roman"">         
</span></span></span><![endif]><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Mask-layer inside data (separate GDAL-special pixel-mask-layer inside GTIFF for full transparency; useful
 in combination with GTIFF inside JPEG-compression, because JPEG can’t hold alpha-channel and NoData doesn’t work calculable caused by lossy compression)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">If compiling GDAL and mapserver by your own, then using libjpeg-turbo instead of libjpeg brings some extra pieces of
 performance, specially when dealing with large amounts of image-data.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">You can define/modify default-formats and add special GDAL compression-options with ‘ FORMATOPTION “KEY=VALUE” ’, do
 not forget to add format to formatlist:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><a href="http://pastebin.com/1YztvEcw">http://pastebin.com/1YztvEcw</a><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Ben<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:#1F497D"><br>
Luftbild und Geoinformationssysteme<br>
Kronprinzenstraße 6<br>
45128 Essen<br>
Fon: +49 201 2069-232<br>
Fax: +49 201 2069-500<br>
<a href="mailto:schepers@rvr-online.de">schepers@rvr-online.de</a><br>
<br>
</span><b><span style="font-size:7.5pt;font-family:"Arial","sans-serif";color:#1F497D">Die Regionaldirektorin<br>
</span></b><span style="font-size:7.5pt;font-family:"Arial","sans-serif";color:#1F497D">Kronprinzenstraße 35<br>
45128 Essen<br>
Zentrale: +49 (0) 201 2069-0<br>
Fax: +49 (0) 201 2069-500<br>
<a href="http://www.metropoleruhr.de">www.metropoleruhr.de</a><br>
<br>
Postfach 10 32 64<br>
45032 Essen<br>
<br>
Steuernummer: RVR 112/5797/0116<br>
USt.-ldNr.: DE 173867500</span><o:p></o:p></p>
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