[gdal-dev] merge two black/white image -> result only black

[Jan Tappenbeck]

hallo !

i had two tif-image and want to merge them:

d:\cad\FWTools2.4.6>gdalinfo c:\temp\geesthacht\586922g.tif
Driver: GTiff/GeoTIFF
Files: c:\temp\geesthacht\586922g.tif
       c:\temp\geesthacht\586922g.tfw
Size is 8000, 8000
Coordinate System is `'
Origin = (3585999.875000000000000,5924000.125000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)
Metadata:
  TIFFTAG_SOFTWARE=IrfanView
  TIFFTAG_XRESOLUTION=508
  TIFFTAG_YRESOLUTION=508
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
Image Structure Metadata:
  COMPRESSION=CCITTFAX4
  INTERLEAVE=BAND
  MINISWHITE=YES
Corner Coordinates:
Upper Left  ( 3585999.875, 5924000.125)
Lower Left  ( 3585999.875, 5922000.125)
Upper Right ( 3587999.875, 5924000.125)
Lower Right ( 3587999.875, 5922000.125)
Center      ( 3586999.875, 5923000.125)
Band 1 Block=8000x1 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
-----------------------------

d:\cad\FWTools2.4.6>gdalinfo c:\temp\geesthacht\586922h.tif
Driver: GTiff/GeoTIFF
Files: c:\temp\geesthacht\586922h.tif
       c:\temp\geesthacht\586922h.tfw
Size is 8000, 8000
Coordinate System is `'
Origin = (3585999.875000000000000,5924000.125000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)
Metadata:
  TIFFTAG_SOFTWARE=IrfanView
  TIFFTAG_XRESOLUTION=508
  TIFFTAG_YRESOLUTION=508
  TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
Image Structure Metadata:
  COMPRESSION=CCITTFAX4
  INTERLEAVE=BAND
  MINISWHITE=YES
Corner Coordinates:
Upper Left  ( 3585999.875, 5924000.125)
Lower Left  ( 3585999.875, 5922000.125)
Upper Right ( 3587999.875, 5924000.125)
Lower Right ( 3587999.875, 5922000.125)
Center      ( 3586999.875, 5923000.125)
Band 1 Block=8000x1 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

i merge with gdal_merge by following command:

d:\cad\FWTools2.4.6>gdal_merge -v -o C:\temp\geesthacht\gh_test.tif -of 
GTiff -co COMPRESS=LZW c:\temp\geesthacht\586922g.tif 
c:\temp\geesthacht\586922h.tif

but when i open the resultfile it is black-complete! !

d:\cad\FWTools2.4.6>gdalinfo c:\temp\geesthacht\gh_test1.tif
Driver: GTiff/GeoTIFF
Files: c:\temp\geesthacht\gh_test1.tif
Size is 8000, 8000
Coordinate System is `'
Origin = (3585999.875000000000000,5924000.125000000000000)
Pixel Size = (0.250000000000000,-0.250000000000000)
Image Structure Metadata:
  COMPRESSION=LZW
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  ( 3585999.875, 5924000.125)
Lower Left  ( 3585999.875, 5922000.125)
Upper Right ( 3587999.875, 5924000.125)
Lower Right ( 3587999.875, 5922000.125)
Center      ( 3586999.875, 5923000.125)
Band 1 Block=8000x1 Type=Byte, ColorInterp=Gray


can anybody tell me why ?????

regards Jan :-)