[R-sig-Geo] Problem with ignoring background value

[Ophelia Wang]

Hi all,

I've been having troubles to get rid of background values (255) of
aerial photo
mosaics (.img) in Erdas Imagine. I've tried "mosaic" (which has options
of
ignore certain input and output background and 0 values), "rescale"
(ignore 0
and 255), ArcGIS copy raster (ignore 0 and 255), etc. etc. Everything
that has
an option to ignore both 0 and 255 that I've tried.

None of those worked in terms of removing the white background of the
aerial
photo mosaics. I have nearly 50 images, so I can't manually create AOI
and then
subset each mosaic based on AOI.

Any suggestions? Thanks for you help.

Ophelia


-- 
Ophelia Wang
PhD candidate
Department of Geography and Environment
University of Texas at Austin
210 West 24th Street, Austin, TX 78712, USA
Phone: 1-512-471-5116
Fax: 1-512-471-5049
Email: opheliawang at mail.utexas.edu