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I need to export color orthophoto map to gray scale geotiff file using free tools (like qgis) any idea?

I tried qgis preview but this does not produce new geotiff file

marked as duplicate by underdark Aug 21 '15 at 18:25

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In QGIS you could use the r.composite module from GRASS in the Processing toolbox. Alternatively you could use the raster calculator to average across the bands, emphasis a particular band over the others, or just export a single band.

You specifically mention GeoTiff, but if you have a world file, you could simply open the tiff in Photoshop or GIMP and change the mode to grey-scale and save as a new file (to retain the original), then copy the tfw file and rename to match the new grey-scale tiff.

  • How can I do it with command line tool so I can run a script on bunch of maps – Eli Alali Mar 10 '15 at 21:35
  • Read the documentation. Also have a look here and here. A quick search will yield many other examples. – MappaGnosis Mar 11 '15 at 7:13

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