On 12/27/2012 02:27 PM, Even Rouault wrote:
The artifacts are due to the lossy characteristics of JPEG compression that
are particularly visible on borders between nodata pixel and valid pixels. An
option would be to use nearblack to create a .msk mask file :
nearblack -setmask -o big_with_mask.tif big.tif -of gtiff
(I'm not sure if your original image has black or white nodata areas. If it is
white, then add -white to the previous command line)
And then do the gdal_translate with big_with_mask.tif as input (you should
perhaps consider adding "-co TILED=YES" too), and then gdaladdo. I've just
pushed a fix since building overviews with "--config COMPRESS_OVERVIEW JPEG --
config PHOTOMETRIC_OVERVIEW
YCBCR" when there's a .msk didn't work.
MapServer should be able to use the mask file as a transparency mask.
OK Even, thanks. This means that I should use gdal-svn?
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