On Fri, Mar 23, 2012 at 10:29 AM, Chaitanya kumar CH <chaitanya...@gmail.com> wrote: > Output pixel value = (raw pixel value * scale) + offset
Exactly. The reason for scale and offset to exist is that "real world" measures like elevation, temperature, pressure are often represented in raster datasets as integer values rescaled from some original floating point values. This is done for compactness in raster format and because many raster formats don't support floating point pixels at all. So for instance, if you have a dataset with temperatures between -20 and 100 you might record them in byte values such with an offset -20 and scale 2.0 which would provide for half degree precision over the range in byte values. So a temperature of 80 would be represented as byte value of "50". The real temperature would be: 50 * 2 - 20 = 80 Best regards, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmer...@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Software Developer _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
