Stefan,<br><br>I haven't tested the script but doesn't the current code copy the alpha band? If it does, it might be more preferable to copy all the pixels and the alpha band.<br><br>Please create a ticket at <a href="http://trac.osgeo.org/gdal/newticket">http://trac.osgeo.org/gdal/newticket</a> and attach your patch.<br>
<br><div class="gmail_quote">On Tue, Jun 29, 2010 at 8:19 PM, Stefan Klug <span dir="ltr"><<a href="mailto:Klug.Stefan@gmx.de">Klug.Stefan@gmx.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Hi,<br>
<br>
gdal_merge.py doesn't handle tiff files with alpha masks so I've added this functionality.<br>
<br>
My patch changes the behaviour of gdal_merge as follows:<br>
- If a band is recognized as Alpha Band it is automatically treated as having a NODATA value of 0.<br>
I'm not sure if this is the way to go. But it makes some sense, as the resulting alpha channel is a correct alpha merge, independent of the nodata value used for the other bands.<br>
- If a band has mask flag GMF_ALPHA set, the mask band controls the parts that get written to the destination<br>
<br>
Would be great if someone could review and possibly checkin the patch.<br>
<br>
Regards<br><font color="#888888">
Stefan<br>
<br>
<br>
<br>
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