Daniela_06 Posted May 14, 2013 Report Share Posted May 14, 2013 Hello, I am doing an unsupervised classification using ENVI. I have an ETM+ 1992 image already orthorectified and I have mask the study are of interest (administration boundary). Anyway when I perform an unsup classification the background is being classified. How to eliminate the black background of all the imageS? Quote Link to comment Share on other sites More sharing options...
Daniela_06 Posted May 14, 2013 Author Report Share Posted May 14, 2013 Let me be more clear. I did a ¨extract by mask¨ using ARCMAP to mask the area that i needed from the whole satellite image. And then saved this new image as .tif to open in ENVI. The new image in envi shows the are that I want and a black background and when classifying using unsupervised classification in also classifies the background. How can i fix this so that the background of the image is not part of any classification. Quote Link to comment Share on other sites More sharing options...
geogeek28 Posted May 15, 2013 Report Share Posted May 15, 2013 (edited) Use ArcMap Raster calculator and input this formula: SetNull( "Input raster" == 0, "Input raster" ). This is for ArcGIS 10, 10.1, these versions use Python syntax. For 9.3 use square brackets at input raster Edited May 15, 2013 by geogeek28 1 Quote Link to comment Share on other sites More sharing options...
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