8 Feb 1994
This directory contains revised versions of source code files from the
Guide Star Survey Sampler CD-ROM.  All files can be copied in ascii
mode.  These changes have three purposes:

(1) They repair several problems that have been encountered using the
    software on VMS systems.  With the changes we believe the programs
    will work around some problems with the "VFS MOUNT" software that
    is sometimes used to read CD-ROMs on VAXes, and the output FITS and
    hhh/hhd format files should be compatible with any other software.
    (The MODIFY program used with earlier versions is no longer
    needed.)

(2) They include a modification that allows the programs to read the
    CD-ROM files correctly on Unix systems that cause the files to
    appear with uppercase names instead of lowercase names.  This
    happens on at least some Decstations running Ultrix.  If you
    have this problem, edit makefile and remove the comment symbol
    ('#') from the line at the beginning of the file that says

            #MORECFLAGS = -DULTRIX

(3) They provide an entirely new capability to smooth the decompressed
    images by adjusting the H-transform coefficients.  The effect is
    that the "blockiness" that appears in highly compressed images is
    removed.  The smoothing adapts to the structure in the images; for
    example, it does not blur star images.  The smoothing has little
    effect on images at the lowest compression ratio, but produces
    images that appear noticeably more natural on the highest
    compression images.  The changes are most dramatic for images that
    include some extended emission (nebulosity or large galaxies).

To build the program, copy these new files and compile the programs
again using the "make" command for Unix or "@make" for VMS.  Run the
programs as before, but optionally add the switch "-s" to the command
line to specify that the extracted images should be smoothed.  For
example, to run IMEXTRCT, the program that extracts an image at a
specified RA and Dec, do

        imextract.csh -s high    (Unix)
        @imextrct -s high       (VMS)

to extract a smoothed image from the high compression version of the
plates.  As before, if the compression ratio (low, medium, or high) is
omitted the low compression plates are used; if the smoothing switch is
omitted then the images are not smoothed.

Copyright (c) 1993 Association of Universities for Research
in Astronomy. All rights reserved. Produced under National
Aeronautics and Space Administration Contract No. NAS5-26555.

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