Hi Chaitanya, thanks, i'll try that when I get back to it tomorrow.
But: I guess I will have to add -vrtnodata aswell, hopefully it will add pixels to the mask ? I have already converted all the source TIFFs to lossless compressed GeoTiff (which don't produce undesired JPEG artifacts), and made a VRT that tiles them together using -vrtnodata (suggestion from Michael Smith). This works well, but having compression with JPEG + mask would be nice. Some of the files are still quite large (including gdaladdo overviews) -- Oyvind On Tue, Apr 3, 2012 at 7:35 PM, Chaitanya kumar CH <chaitanya...@gmail.com>wrote: > Oyvind, > > One easy method is to create a vrt file with an alpha band for the > original tiff. You can use this to create a compressed raster file that > will be > transparent at nodata pixels. > > gdalbuildvrt -addalpha > > http://www.gdal.org/gdalbuildvrt.html > > On Tue, Apr 3, 2012 at 5:26 PM, Oyvind Idland <oyvind.idl...@gmail.com>wrote: > >> Hello, >> >> >> I got one problem: I have a bunch of uncompressed TIFF tiles, which I am >> converting to compressed GeoTiff. I would >> like to mask away the rgb(0,0,0) values. >> >> However, when I use NODATA on my VRT dataset, there are JPEG artifacts >> around the edges when rendering. >> >> Is it possible to generate a transparency mask based on NDATA before >> compressing, or is there any other/better way of >> doing this ? >> >> thanks, >> >> - oyvind >> >> >> _______________________________________________ >> gdal-dev mailing list >> gdal-dev@lists.osgeo.org >> http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > > > -- > Best regards, > Chaitanya kumar CH. > > +91-9494447584 > 17.2416N 80.1426E >
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