[Qgis-user] problem to merge bitonale transparent image

[Jan Tappenbeck]

hi !

i had to merge some transparent images.

the basic images have following parameters:

Driver: GTiff/GeoTIFF
Files: 
G:/Support/Projektdaten/yyyy/dgk5/ETRS_89/transparent/grundriss/trans/6880g_06.tif
Size is 6299, 6299
Coordinate System is `'
Origin = (358564.815772434930000,5681666.068979292200000)
Pixel Size = (0.330145261400000,-0.330144626700000)
Metadata:
   TIFFTAG_RESOLUTIONUNIT=2 (pixels/inch)
   TIFFTAG_XRESOLUTION=400
   TIFFTAG_YRESOLUTION=400
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  358564.816, 5681666.069)
Lower Left  (  358564.816, 5679586.488)
Upper Right (  360644.401, 5681666.069)
Lower Right (  360644.401, 5679586.488)
Center      (  359604.608, 5680626.278)
Band 1 Block=6299x1 Type=Byte, ColorInterp=Palette
   NoData Value=0
   Color Table (RGB with 256 entries)
     0: 255,255,255,255
     1: 0,0,0,255
     2: 0,0,0,255
...
   254: 0,0,0,255
   255: 0,0,0,255

the command to merge by qgis will be:
gdal_merge.bat -of GTiff -o xxxxxx

the problem is that the result image only will be show black - here the 
parameters:

Driver: GTiff/GeoTIFF
Files: 
G:/Support/Projektdaten/yyyy/dgk5/ETRS_89/transparent/grundriss/trans/merge_grund.tif
Size is 31496, 31248
Coordinate System is `'
Origin = (358564.815772434930000,5689657.747518299100000)
Pixel Size = (0.330145261400000,-0.330144626700000)
Image Structure Metadata:
   INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  358564.816, 5689657.748)
Lower Left  (  358564.816, 5679341.388)
Upper Right (  368963.071, 5689657.748)
Lower Right (  368963.071, 5679341.388)
Center      (  363763.943, 5684499.568)
Band 1 Block=31496x1 Type=Byte, ColorInterp=Gray

did anyone help me to get the right result?

regards Jan :-)