Hi, Phase 1) let's assume i convert the geotiff -> "file1.tif" to ascii grid file -> "file2.txt"... Phase 2) later on i change some of the values of file2.txt, now i want to again convert the file2.txt (with changed data part...) to geotiff with the projection information of file1.tif... Can you help me to work around this phase? Thanks, Riki