CLIP will search through the 'source' image and replace all pixels with
intensities above MAX with VMAX and all pixels below MIN with VMIN. If
VMIN and VMAX are not specified, they default to zero.
If VMIN or VMAX are specified, but no MIN or MAX are not, the routine clips
at the values given by VMIN or VMAX. If neither MAX nor VMAX are
specified, no upper level clipping will be performed. Similarly, if
neither MIN nor VMIN is specified, but MAX or VMAX is, no lower level
clipping will be performed.
If no keywords are given, CLIP will set all negative pixels to
zero.
You can use the 'BOX=n' keyword to only clip those portions of the image
within box 'n'. Multiple boxes can also be specified on the command line
to clip within more than one region at a time.
If the MASK keywords is given, a MASK is created (see the MASK command) of
the pixels that are being clipped. The related MASKONLY keyword will
create a mask without doing the actual clipping. Masks can also
be used for clipping with the VMASK=n keyword. All masked pixels will be
replaced with the value 'n' in this option. The various MASK options are
useful with commands such as the SURFACE command that permit the use of
image masks to tag certain pixels before a surface is fit to an image.
Note, however, that not all commands recognize masks.
If the RAD=r keyword is used, all pixels within r pixels of the selected
pixels will be clipped to the specified value. If the PHOT=r keyword is
used, all pixels within r pixels of all the locations on the current VISTA
photometry list that satisfy the clipping criteria will be clipped to the
values specified with VMAX= and VMIN=. This is a way to clip and/or mask
out stars on an image previously identified with the VISTA stellar
photometry routines.
<#4743#>Examples:<#4743#>