using QGIS 2.6
I import a TIF file, and expect the import to show an image that has black lines on a white background (with some other colors here and there), as the native windows viewer will see a white background. The file, 49MB, imports, but
The TIF image has a dark gray background instead of a white background
I can't tell why. Any hints?
The same thing happens if I import the TIF image into georeference, which is how I discovered this in the first place.
I created/exported the TIF image using PDFCreator (from a print of a PDF to a TIF, using that program). Within PDFCreator, I chose a TIF export that set the color map to 4096 colors, as the default created a TIF file that was twice as large.
On testing with the default size (16 million colors or some such).... That file imported and showed the background as white.
And I can't tell why, for that, either. Any hints?
======== In response to the comment/question by @BradHards:
The TIFFTAG_PHOTOMETRIC is not present in either file.
The gdalinfo for the large file and small file are identical, but for the presence of two extra lines on the file where the white background turns to dark gray. Each band sets NBITS=4 for Image Structure Metadata: eg:
Band 1 Block=5100x68 Type=Byte, ColorInterp=Red Image Structure Metadata: NBITS=4 Band 2 Block=5100x68 Type=Byte, ColorInterp=Green Image Structure Metadata: NBITS=4 Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue Image Structure Metadata: NBITS=4
Something about the NBITS=4 state turns the background dark gray. Alternatively, there is some other problem with the PDFCreator export.
These are the full GDALInfo:
Small with dark gray background:
Driver: GTiff/GeoTIFF Files: small file.tif Size is 5100, 6600 Coordinate System is `' Metadata: TIFFTAG_DATETIME=2015:01:28 16:41:04 TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) TIFFTAG_SOFTWARE=GPL Ghostscript 9.07 TIFFTAG_XRESOLUTION=600 TIFFTAG_YRESOLUTION=600 Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 0.0, 0.0) Lower Left ( 0.0, 6600.0) Upper Right ( 5100.0, 0.0) Lower Right ( 5100.0, 6600.0) Center ( 2550.0, 3300.0) Band 1 Block=5100x68 Type=Byte, ColorInterp=Red Image Structure Metadata: NBITS=4 Band 2 Block=5100x68 Type=Byte, ColorInterp=Green Image Structure Metadata: NBITS=4 Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue Image Structure Metadata: NBITS=4
Large with white background
Driver: GTiff/GeoTIFF Files: larger file.tif Size is 5100, 6600 Coordinate System is `' Metadata: TIFFTAG_DATETIME=2015:01:28 17:07:16 TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch) TIFFTAG_SOFTWARE=GPL Ghostscript 9.07 TIFFTAG_XRESOLUTION=600 TIFFTAG_YRESOLUTION=600 Image Structure Metadata: INTERLEAVE=PIXEL Corner Coordinates: Upper Left ( 0.0, 0.0) Lower Left ( 0.0, 6600.0) Upper Right ( 5100.0, 0.0) Lower Right ( 5100.0, 6600.0) Center ( 2550.0, 3300.0) Band 1 Block=5100x68 Type=Byte, ColorInterp=Red Band 2 Block=5100x68 Type=Byte, ColorInterp=Green Band 3 Block=5100x68 Type=Byte, ColorInterp=Blue