I am looking at a 2005 landsat image, and I used the IAW to calculate the NDVI... easy-peasy! But everything I have read about the NDVI's says that the resulting calculations should be in a range from -1.0 to +1.0 with negative number signifying vegetation loss and the positive values signifying vegetation gain. I am not seeing this. When I create an attribute table from the NDVI raster, the values are on a 0-256 scale. How do I create the NDVI values for the raster in the -1.0 to +1.0 range?