Rob,<br><br>You can try the -dstalpha option in gdalwarp to create an alpha band. (<a href="http://www.gdal.org/gdalwarp.html">http://www.gdal.org/gdalwarp.html</a>)<br><br><div class="gmail_quote">On Fri, Jun 18, 2010 at 7:22 PM, Rob <span dir="ltr"><<a href="mailto:gis@vanbooth.com">gis@vanbooth.com</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 Guys<br><br>I'm reprojecting some rasters from OSGB (EPSG:27700) to WGS84 (EPSG:4326) and am running into a problem.<br>
<br>The rasters are reprojecting nicely, but I am left with black pixels around the image where the reprojected image doesnt fit squarely within the rectangular dimensions of the file.<br>
<br>I posted about this issue a few weeks ago, and then realised that I should be marking that colour as transparent when rendering using GeoServer, and ho! everything was OK.<br><br>However, I am now reprojecting some greyscale rasters, and by making the black pixels on the outside transparent, I am losing the black details of the raster image that I want to display!<br>
<br>Is there a way of selecting the colour that gdal uses to populate these dead pixels around the side?<br><br>MTIA<br><font color="#888888"><br>Rob<br>
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