LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
November 2011
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
2011.11.30 13:58 "Re: Inconsistent metadata report for CMYK 8-bit image", by Even Rouault
> > #################################################################### > 2) gdalinfo (from current OSGeo4W package) > > C:\> gdalinfo Shadow_cmyk8.tif > Warning 1: TIFFReadDirectory:Unknown field with tag 37724 (0x935c) > encountered > Driver: GTiff/GeoTIFF > Files: Shadow_cmyk8.tif > Size is 768, 505 > Coordinate System is `' > Metadata: > TIFFTAG_SOFTWARE=Adobe Photoshop CS3 Windows > TIFFTAG_DATETIME=2011:10:31 14:09:04 > TIFFTAG_XRESOLUTION=72 > TIFFTAG_YRESOLUTION=72 > TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) > Image Structure Metadata: > SOURCE_COLOR_SPACE=CMYK > INTERLEAVE=PIXEL > Corner Coordinates: > Upper Left ( 0.0, 0.0) > Lower Left ( 0.0, 505.0) > Upper Right ( 768.0, 0.0) > Lower Right ( 768.0, 505.0) > Center ( 384.0, 252.5) > Band 1 Block=768x2 Type=Byte, ColorInterp=Red > Mask Flags: PER_DATASET ALPHA > Band 2 Block=768x2 Type=Byte, ColorInterp=Green > Mask Flags: PER_DATASET ALPHA > Band 3 Block=768x2 Type=Byte, ColorInterp=Blue > Mask Flags: PER_DATASET ALPHA > Band 4 Block=768x2 Type=Byte, ColorInterp=Alpha > > Which one is right? > How many bits per sample and how many samples per pixel is there? By default, with unusual color spaces like CMYK, GDAL will go through the libtiff RGBA API that does the colorspaces conversions and expose a regular RGBA dataset to GDAL. You can try however : gdalinfo GTIFF_RAW:Shadow_cmyk8.tif and with latest trunk (and likely 1.8 too), you'll see : C:\gdal_trunk\gdal>gdalinfo GTIFF_RAW:Shadow_cmyk8.tif Driver: GTiff/GeoTIFF Files: Shadow_cmyk8.tif Size is 768, 505 Coordinate System is `' Metadata: TIFFTAG_DATETIME=2011:10:31 14:09:04 TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) TIFFTAG_SOFTWARE=Adobe Photoshop CS3 Windows TIFFTAG_XRESOLUTION=72 TIFFTAG_YRESOLUTION=72 Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 0.0, 0.0) Lower Left ( 0.0, 505.0) Upper Right ( 768.0, 0.0) Lower Right ( 768.0, 505.0) Center ( 384.0, 252.5) Band 1 Block=768x2 Type=Byte, ColorInterp=Cyan Band 2 Block=768x2 Type=Byte, ColorInterp=Magenta Band 3 Block=768x2 Type=Byte, ColorInterp=Yellow Band 4 Block=768x2 Type=Byte, ColorInterp=Black Band 5 Block=768x2 Type=Byte, ColorInterp=Black Note the wrong color interpretation was wrong for the last band. The code assumed that for CMYK, you have only 4 bands. I've just fixed that in trunk, and now it reports alpha for band 5. > > Best regards, > -- > Mateusz Loskot, http://mateusz.loskot.net > Charter Member of OSGeo, http://osgeo.org > Member of ACCU, http://accu.org > _______________________________________________ > Tiff mailing list: Tiff@lists.maptools.org > http://lists.maptools.org/mailman/listinfo/tiff > http://www.remotesensing.org/libtiff/ >