Hi Jason,
The following two should help:
http://gis.stackexchange.com/questions/114370/compression-artifacts-and-gdal
http://osgeo-org.1560.x6.nabble.com/gdal-dev-JPEG-compressed-GeoTIFF-ignores-Nodata-td3746232.html
Cheers,
Jonathan
---- On Thu, 14 Apr 2016 21:36:59 +0100 Jason
Newmoyer<[email protected]> wrote ----
GeoTIFF gurus,
I am trying to figure out the best way to deal with the unfortunate "black
areas" that occur frequently in our downloaded satellite imagery. I set the
OutputTransparentColor to 000000 and it works fine for uncompressed or
losslessly compressed data just fine. However, when using JPEG-In-TIFF for max
compression/space savings, you get the dreaded black edge created by JPEG
compression.
I am using GDAL command line utilities.
With lossless compression like LZW, but only get about 2:1 compression.
I want to use JPEG-In-TIFF with YCBCR colorspace for 20:1 compression goodness.
If I crank up the the JPEG_QUALITY to 100 it helps, but still pretty
noticeable.
I have tried using "-mask mask" options in gdal_translate when I convert from
the original format. But I'm not really sure what that does since the
documentation is thin. There seems to be no way to tell it to create a new mask
band using any source values of 0,0,0 as nodata.
I have put together a quick Word doc with visuals of 3 different options - LZW,
JPEG 100, and JPEG 80 showing files size and resulting layer preview in
GeoServer.
I have tried various tricks with RasterSymbolizer like trying to set
"nearblack" pixels to zero. But that will effect "good" data too, so not a very
good option.
Any suggestions on this would be greatly appreciated. Thanks!
Jason Newmoyer
Newmoyer Geospatial [email protected]
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