Even, Thank you very much ! With the two creation options : PHOTOMETRIC=RGB and ALPHA=NO, I obtain the same behaviour I whish.
Can you explain me where you found this answer ? (to help me to become more autonomous with GDAL) Thank you again Nicky 2011/4/18 Even Rouault <even.roua...@mines-paris.org> > Selon Nicolas Mayer <nmayer31...@gmail.com>: > > > Even, thank you very much for answering me so quicly > > > > With the PHOTOMETRIC creation option to MINISBLACK, I get now : > > Band 1 Block=100x20 Type=Byte, ColorInterp=Gray > > Band 2 Block=100x20 Type=Byte, ColorInterp=Undefined > > Band 3 Block=100x20 Type=Byte, ColorInterp=Undefined > > Band 4 Block=100x20 Type=Byte, ColorInterp=Undefined > > > > Does this option change anything in the metadatas or in the headers of > the > > written file ? > > Yes of course, otherwise how would you explain you get a difference ;-) ? > This > change the value of the PHOTOMETRIC tiff tag in TIFF file. > > > > > But I try to make the same thing as an exemple file I have, which has > this > > interpretation whith gdalinfo (GDAL 1.7.3) : > > > > Metadata: > > TIFFTAG_IMAGEDESCRIPTION=B3 B2 B1 B4 > > TIFFTAG_DATETIME=20050824 18:08:22 > > AREA_OR_POINT=Point > > Image Structure Metadata: > > INTERLEAVE=BAND > > Corner Coordinates: > > Upper Left ( 0.0, 0.0) > > Lower Left ( 0.0, 3000.0) > > Upper Right ( 3000.0, 0.0) > > Lower Right ( 3000.0, 3000.0) > > Center ( 1500.0, 1500.0) > > Band 1 Block=3000x500 Type=Byte, ColorInterp=Red > > Band 2 Block=3000x500 Type=Byte, ColorInterp=Green > > Band 3 Block=3000x500 Type=Byte, ColorInterp=Blue > > Band 4 Block=3000x500 Type=Byte, ColorInterp=Undefined > > > > My goal is to have an "RGB-Undefined" color interpretation. > > Have you any idea of the creation option (or driver option ?) to set to > have > > the same color interpretations ? > > Actually after looking more precisely at the code and a bit of testing, I > see > you can obtain the behaviour you wish by specifying both PHOTOMETRIC=RGB > and > ALPHA=NO. (ALPHA=NO only will not be sufficient) > > > > > Thank you in advance > > > > Nicky > > > > > > > > 2011/4/18 Even Rouault <even.roua...@mines-paris.org> > > > > > Selon Nicolas Mayer <nmayer31...@gmail.com>: > > > > > > Retry by setting the PHOTOMETRIC creation option to MINISBLACK. > Otherwise, > > > by > > > default, without specifying it, GDAL assumes that the PHOTOMETRIC is > RGB > > > and > > > that the 4th band is an alpha band. > > > > > > You should get : > > > Band 1 Block=100x20 Type=Byte, ColorInterp=Gray > > > Band 2 Block=100x20 Type=Byte, ColorInterp=Undefined > > > Band 3 Block=100x20 Type=Byte, ColorInterp=Undefined > > > Band 4 Block=100x20 Type=Byte, ColorInterp=Undefined > > > > > > There's no way in the TIFF format to really specify the color > > > interpretation of > > > each band. The way GDAL builds the color interpretation when reading a > TIFF > > > file > > > is a combination of the value of the PHOTOMETRIC and EXTRASAMPLES tag. > > > > > > > Hello > > > > > > > > I have a problem with the geotiff (GTiff) driver. > > > > > > > > I create a 4-bands raster image in a c++ program. The fourth band was > > > > considered as an alpha band in the geotiff image (actually, it is > near > > > > infrared : NIR) > > > > > > > > $ gdalinfo new_geotiff.tif > > > > Driver: GTiff/GeoTIFF > > > > Files: new__geotiff.tif > > > > Size is 100, 100 > > > > (...) > > > > Band 1 Block=100x20 Type=Byte, ColorInterp=Red > > > > Mask Flags: PER_DATASET ALPHA > > > > Band 2 Block=100x20 Type=Byte, ColorInterp=Green > > > > Mask Flags: PER_DATASET ALPHA > > > > Band 3 Block=100x20 Type=Byte, ColorInterp=Blue > > > > Mask Flags: PER_DATASET ALPHA > > > > Band 4 Block=100x20 Type=Byte, ColorInterp=Alpha > > > > > > > > How to remove the Color interpretation 'alpha' and the mask flags ? > > > > > > > > I want to have : > > > > > > > > Band 1 Block=100x20 Type=Byte, ColorInterp=Red > > > > Band 2 Block=100x20 Type=Byte, ColorInterp=Green > > > > Band 3 Block=100x20 Type=Byte, ColorInterp=Blue > > > > Band 4 Block=100x20 Type=Byte, ColorInterp=Undefined > > > > > > > > I already tryed : > > > > pDS->GetRasterBand(4)->SetColorInterpretation(GCI_Undefined ); > > > > > > > > I tryed too to set the creation option : "ALPHA" to "NO". > > > > > > > > > > > > Thanks in advance for any help. > > > > > > > > Nicky > > > > > > > > > > > > > > > > > >
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