i.atcorr i.atcorr - Performs atmospheric correction using the 6S algorithm. Imagery (i.*) ParameterRaster|iimg|Name of input raster map|False ParameterBoolean|-a|Input from ETM+ image taken after July 1, 2000|False ParameterBoolean|-b|Input from ETM+ image taken before July 1, 2000|False ParameterRaster|ialt|Input altitude raster map in m (optional)|True ParameterRaster|ivis|Input visibility raster map in km (optional)|True ParameterFile|icnd|Name of input text file|False ParameterRange|iscl|Input imagery range [0,255]|0,255 ParameterBoolean|-o|Try to increase computation speed when altitude and/or visibility map is used|True OutputRaster|oimg|Name for output raster map ParameterBoolean|-f|Output raster is floating point|False ParameterRange|oscl|Rescale output raster map [0,255]|0,255