[gdal-dev] Merging tiff4 files

[Etienne Tourigny]

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 <aperi2007 at gmail.com> 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 <warmerdam at pobox.com>
>>
>> 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 <aperi2007 at gmail.com> 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
>> > gdal-dev at lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/gdal-dev
>> >
>>
>>
>>
>> --
>> ---------------------------------------+--------------------------------------
>> I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
>> light and sound - activate the windows | http://pobox.com/~warmerdam
>> and watch the world go round - Rush    | Geospatial Software Developer
>
>
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
>
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