Trim
images from SCUBA-2 to a given size. The image may be trimmed using given spatial
dimensions or a statistical estimator to threshold the image. In the former case, the output map is
rectangular or circular; in the latter the shape is determined by the values in the image
itself.
By default the method employs the map parameters in the FITS header. The map width and height
may be overridden with recipe parameters. Note that if a map radius is given (when a circular output
image is desired) the height and width are ignored.
The JCMT::MapArea Perl module is used to define a (rectangular) AST Region using the map
parameters in the FITS header.
For the statistical estimator, the default is to trim the map excluding data where the exposure time is
less than half of the median value.
The following parameters can be set via the -recpars option:
CROP_METHOD
Method to use for cropping image. May be statistical, rectangle (default) or circle,
each of which may be abbreviated to the first four characters.
MAP_HEIGHT
Height of output
image in arcsec.
MAP_RADIUS
Radius of output image in arcsec. Overrides existence of
MAP_HEIGHT and MAP_WIDTH.
MAP_WIDTH
Width of output image in arcsec.
STATS_COMP
NDF component to use to define the threshold. May be texp to use the exposure time
image, or var or err to use the variance or error components.
STATS_ESTIMATOR
Statistical
estimator for thresholding the image. May be MEAN, MEDIAN, MODE, MAX, MIN.
STATS_THRESH
Multiplier for STATS_ESTIMATOR above. Default is 1 if not specified (or 0.5 for
texp).
None.