gdal question on no data.

[Paul Moen]

Does anyone know how to take a tiff and apply jpeg compression without
messing up the nodata areas?  For example, I have a tif with weather radar
imagery in colors black is the nodata color.  I want to compress the tif
using jpeg compression, but the compression causes some of the nodata colors
to become something other than black.  Is there a way to tell gdal to
consider the black areas no data and do not use them in the compression
process? 

gdal_translate -a_srs "epsg:2266" -co "COMPRESS=JPEG" 40.tif 40n.tif


Paul T. Moen