Hi Everyone, I am having some trouble figuring out why adding JPEG compression to a RGB GeoTIFF results in Nodata pixel triplets becoming data pixel triplets. Is this expected behavior due to the noisy nature of JPEG compression or to the fact that these are border Nodata triplets? I know certain algorithms process the boundary between data and Nodata differently.
I'm running GDAL 1.8.0 with internal libtiff. The command I issued was: gdal_translate -co COMPRESS=JPEG -co TILED=YES -co JPEG_QUALITY=90 -co PHOTOMETRIC=YCBCR s70rgb321.tif test.tif In QGIS using the identify feature on the same triplets results in: s70rgb321.tif: Band 1: null(nodata) Band 2: null(nodata) Band 3: null(nodata) test.tif: Band 1: 1 Band 2: 1 Band 3: 3 gdalinfo s70rgb321.tif yields: Driver: GTiff/GeoTIFF Files: s70rgb321.tif s70rgb321.tif.ovr Size is 32261, 30632 Coordinate System is: PROJCS["Pulkovo_1942_58_Stereo70", GEOGCS["GCS_Pulkovo 1942(58)", DATUM["Pulkovo_1942_58", SPHEROID["Krassowsky_1940",6378245,298.3, AUTHORITY["EPSG","7024"]], AUTHORITY["EPSG","6179"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433]], PROJECTION["Oblique_Stereographic"], PARAMETER["latitude_of_origin",46], PARAMETER["central_meridian",25], PARAMETER["scale_factor",0.99975], PARAMETER["false_easting",500000], PARAMETER["false_northing",500000], UNIT["metre",1, AUTHORITY["EPSG","9001"]]] Origin = (27432.591760581413837,941642.761553813470528) Pixel Size = (28.512429802339831,-28.512429802339831) Metadata: AREA_OR_POINT=Area Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 27432.592, 941642.762) ( 18d26'17.19"E, 49d47'26.40"N) Lower Left ( 27432.592, 68250.012) ( 19d18' 9.44"E, 41d58' 4.57"N) Upper Right ( 947272.090, 941642.762) ( 31d12'45.10"E, 49d48'33.95"N) Lower Right ( 947272.090, 68250.012) ( 30d23'36.76"E, 41d58'59.57"N) Center ( 487352.341, 504946.387) ( 24d50'11.61"E, 46d 2'39.82"N) Band 1 Block=32261x1 Type=Byte, ColorInterp=Red NoData Value=0 Overviews: 16131x15316, 8066x7658, 4033x3829, 2017x1915, 1009x958, 505x479, 253x240 Metadata: LAYER_TYPE=athematic Band 2 Block=32261x1 Type=Byte, ColorInterp=Green NoData Value=0 Overviews: 16131x15316, 8066x7658, 4033x3829, 2017x1915, 1009x958, 505x479, 253x240 Metadata: LAYER_TYPE=athematic Band 3 Block=32261x1 Type=Byte, ColorInterp=Blue NoData Value=0 Overviews: 16131x15316, 8066x7658, 4033x3829, 2017x1915, 1009x958, 505x479, 253x240 Metadata: LAYER_TYPE=athematic gdalinfo test.tif yields: Driver: GTiff/GeoTIFF Files: test.tif Size is 32261, 30632 Coordinate System is: PROJCS["Pulkovo_1942_58_Stereo70", GEOGCS["GCS_Pulkovo 1942(58)", DATUM["Pulkovo_1942_58", SPHEROID["Krassowsky 1940",6378245,298.2999999999998, AUTHORITY["EPSG","7024"]], AUTHORITY["EPSG","6179"]], PRIMEM["Greenwich",0], UNIT["degree",0.0174532925199433]], PROJECTION["Oblique_Stereographic"], PARAMETER["latitude_of_origin",46], PARAMETER["central_meridian",25], PARAMETER["scale_factor",0.99975], PARAMETER["false_easting",500000], PARAMETER["false_northing",500000], UNIT["metre",1, AUTHORITY["EPSG","9001"]]] Origin = (27432.591760581413837,941642.761553813470528) Pixel Size = (28.512429802339831,-28.512429802339831) Metadata: AREA_OR_POINT=Area Image Structure Metadata: SOURCE_COLOR_SPACE=YCbCr COMPRESSION=YCbCr JPEG INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 27432.592, 941642.762) ( 18d26'17.19"E, 49d47'26.40"N) Lower Left ( 27432.592, 68250.012) ( 19d18' 9.44"E, 41d58' 4.57"N) Upper Right ( 947272.090, 941642.762) ( 31d12'45.10"E, 49d48'33.95"N) Lower Right ( 947272.090, 68250.012) ( 30d23'36.76"E, 41d58'59.57"N) Center ( 487352.341, 504946.387) ( 24d50'11.61"E, 46d 2'39.82"N) Band 1 Block=256x256 Type=Byte, ColorInterp=Red NoData Value=0 Metadata: LAYER_TYPE=athematic Band 2 Block=256x256 Type=Byte, ColorInterp=Green NoData Value=0 Metadata: LAYER_TYPE=athematic Band 3 Block=256x256 Type=Byte, ColorInterp=Blue NoData Value=0 Metadata: LAYER_TYPE=athematic Thanks for any insights you might have. -marius _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev