[Geotiff] processing no data in GeoTIFF

[Rainer Spittel]

Hi there,
 
  I am totally new in this forum and I am just a GeoTIFF user. Now I have to
process GeoTIFF imagery and have some general problems.
 
  I have to process a number of tiles and have to identify no data areas.
The TIFF images are 24BIT and the "no data" area is a black and a WHITE area
in a tile.
 
  I would like to identify all tiles (filenames), which have a cluster of at
least 4 pixels in one (white) or the other (black) color. 
 
  I tried to find a way using gdal, but was not successfully. May somebody
has an idea to process the GeoTIFF imagery.
 
Cheers

rainer spittel

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