NAME

imcompress -- Compress IRAF image pixel file

USAGE

imcompress images

PARAMETERS

images

List of IRAF images to compress.

verbose = no

Verbose operation ?. If this switch is set to yes then the task will output information about the compress operation and the image header update.

DESCRIPTION

This is a CL script that compresses the pixel file for each image in the input list, and also updates the image header with the new pixel file name. The pixel file compression is performed in place, and a ".Z" is appended to the pixel file name. The actual compression is performed by the UNIX utility compress . This program is called by the task as a foreign task.

EXAMPLES

Compress an IRAF image with the verbose switch set. The pixel file is stored in the same place as the image header (HDR$).

co> imcompress test.imh verbose=yes
test.pix: Compression: 86.00% -- replaced with test.pix.Z
test,i_pixfile: HDR$test.pix -> HDR$test.pix.Z
test updated

TIME REQUIREMENTS

It takes about ten seconds to compress a 512x512 short image, on a SparcStation-1 with a SCSI disk.

BUGS

The task cannot be run in the background because it calls imgets to get the name of the pixel file from the image header.
The task does not use the IRAF networking to access the pixel file because it calls the UNIX program compress as a foreign task. Therefore, the pixel file must be accessible at the host level, either in the local disk or via the Network File System (NFS).
The compress operation is performed in place, so the user must have read and write access to the IRAF image.
If, for some reason, the compress operation cannot be performed by compress , the pixel file name in the image header might not be equal to the actual pixel file name. The only workaround to this problem is to use hedit to fix the problem by hand.
The task might leave some temporary files in the current directory if it is aborted by the user before it completes.

SEE ALSO

compression.imuncompress, images.hedit, (UNIX) compress.