Andrea, please read the gtiff driver page at http://www.gdal.org/frmt_gtiff.html
you need to add a few options, such as -co COMPRESS=CCITTFAX4 -co NBITS=1 Etienne On Fri, Sep 2, 2011 at 7:15 PM, Andrea Peri <[email protected]> wrote: > > Hi Frank, > thx for very rapid response. > > gdal_merge.py now work and the result is intellegible. > > testing the result , > I notice the result is a 256 color image. > > Instead the starting image was true CCITTFax4 raster. > This mean a huge dimension of files. > > Is possible to have a real Tiff4 (1 bit color) image as result ? > > Thx, > > Andrea. > > 2011/9/2 Frank Warmerdam <[email protected]> >> >> Andrea, >> >> I think the problem is that these are one bit files with >> a black/white color table and by default gdal_merge.py >> does not copy the color table. If you add the -pct >> switch it should do so. >> >> I imagine the result file does have pixels with values of >> zero and one, but you won't see them as different in >> most viewers. >> >> Best regards, >> >> On Fri, Sep 2, 2011 at 2:40 PM, Andrea Peri <[email protected]> wrote: >> > Hi, >> > I need to merge some Tiff4 (bw) raster and obtain 1 only more big tiff4 >> > raster. >> > >> > I'm try-ing this with gdal_merge.py >> > and using a comand like this: >> > >> > python gdal_merge.py -o ../raster/216.tif -n 1 -ot Byte >> > ../raster/10k/216*.tif >> > >> > Unfortunately the resulted raster is intellegible (the input raster was all >> > clearly visible). >> > It is an all black image :( >> > >> > I tried also with option "-n 0" but the result is the same. >> > >> > I analyze the input raster using gdalinfo, and the result is this. >> > >> > ------------------ >> >>gdalinfo.exe ../raster/10k/216100.tif >> > Driver: GTiff/GeoTIFF >> > Files: ../raster/10k/216100.tif >> > ../raster/10k/216100.tfw >> > Size is 10065, 10049 >> > Coordinate System is: >> > LOCAL_CS["unnamed", >> > UNIT["unknown",1]] >> > Origin = (1561222.860009765700000,4927094.449960937700000) >> > Pixel Size = (0.500000000000000,-0.500000000000000) >> > Metadata: >> > AREA_OR_POINT=Point >> > TIFFTAG_RESOLUTIONUNIT=1 (unitless) >> > TIFFTAG_SOFTWARE=Arc/Info >> > TIFFTAG_XRESOLUTION=2 >> > TIFFTAG_YRESOLUTION=2 >> > Image Structure Metadata: >> > COMPRESSION=CCITTFAX4 >> > INTERLEAVE=BAND >> > MINISWHITE=YES >> > Corner Coordinates: >> > Upper Left ( 1561222.860, 4927094.450) >> > Lower Left ( 1561222.860, 4922069.950) >> > Upper Right ( 1566255.360, 4927094.450) >> > Lower Right ( 1566255.360, 4922069.950) >> > Center ( 1563739.110, 4924582.200) >> > Band 1 Block=10065x32 Type=Byte, ColorInterp=Palette >> > Image Structure Metadata: >> > NBITS=1 >> > Color Table (RGB with 2 entries) >> > 0: 255,255,255,255 >> > 1: 0,0,0,255 >> > ----------------- >> > >> > What am I wrong ? >> > >> > Thx, >> > >> > -- >> > ----------------- >> > Andrea Peri >> > . . . . . . . . . >> > qwerty àèìòù >> > ----------------- >> > >> > >> > _______________________________________________ >> > gdal-dev mailing list >> > [email protected] >> > http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > >> >> >> >> -- >> ---------------------------------------+-------------------------------------- >> I set the clouds in motion - turn up | Frank Warmerdam, [email protected] >> light and sound - activate the windows | http://pobox.com/~warmerdam >> and watch the world go round - Rush | Geospatial Software Developer > > > > -- > ----------------- > Andrea Peri > . . . . . . . . . > qwerty àèìòù > ----------------- > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
