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IREGION
This allows a spatial region to be defined in a comprehensive and
flexible way. Input to define the region may be by cursor, by
keyboard or by ARD (Ascii Region Definition) text input. Regions
may be defined cumulatively and more complex shapes may be created
by the use of logical operations. The cumulative region is stored
internally as ARD text which may be exported to a file, subsequently
to be used as input to sorting or other applications. The ARD text
or logical mask derived from it is also passed internally to other
image processing commands eg. ISTATS, IEXCLUDE...
The operation of the command is controlled by the MODE parameter, the
value of which may be prefixed with logical operators. Responding
with 'HELP' will list the possible values of both mode and prefix
to the screen. Only the first 3 characters of the mode value is
required and it is not sensitive to case. The following modes are
available:
- BOX
- rectangular region parallel to axes
- SLICE
- rectangular slice at any orientation
- POLYGON
- any polygon entered via cursor as a series of points
- CIRCLE
- circular region
- ANNULUS
- annular region
- ELLIPSE
- elliptical region
- CONTOUR
- select region within a specified contour ie. all
pixels above a given level
- XSPOKES
- area corresponding to ribs on ROSAT PSPC images
- WHOLE
- select whole image
- IMPORT
- import ARD text (see separate section on ARD input)
- EXPORT
- export the ARD text for the current region to a file
- SHOW
- show the outline of the current region(s) - this may be
a bit inaccurate if the image is very grainy
- LIST
- list the ARD text for the current region to the screen
- INVERT
- turn the current region inside out
The default operation is for a new region to be created and all
previous ones to be forgotten. To override this the following
prefixes may be added:
- ADD
- add region to existing one
- AND
- select only the overlap with the existing region
- NOT or EXC
- take the region outside the one given
- ADDNOT
- add the area outside the given region to the existing one
- ANDNOT
- select the overlap between the area outside the specified
region and inside the existing one.
Subtopics:
Next: Parameters Up: Image processing commands Prev: Examples