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imagefromimage - Constructor

	Package	general
	Module	images
	Tool	image

Construct a (sub)image from a region of an AIPS++ image

Synopsis
imagefromimage(outfile, infile, region, mask, dropdeg, overwrite)

Arguments

outfile	in	Output sub-image file name
		Allowed:	String
		Default:	unset
infile	in	Input image file name
		Allowed:	String
region	in	The region of interest
		Allowed:	Region tool
		Default:	Whole image
mask	in	OTF mask
		Allowed:	Boolean LEL expression or mask region
		Default:	None
dropdeg	in	Drop degenerate axes
		Allowed:	T or F
		Default:	F
overwrite	in	Overwrite (unprompted) pre-existing output file ?
		Allowed:	T or F
		Default:	F

Returns
Image tool or fail

Description

This constructor applies a region-of-interest to an image file, creates a new image file containing the (sub)image, and associates a new image tool with it.

The input image file may be in native AIPS++, FITS, or Miriad format. Look here for more information on foreign images.

If outfile is given, the (sub)image is written to the specified disk file.

If outfile is unset, the Image tool actually references the input image file. So if you deleted the input image disk file, it would render this tool useless. When you destroy this tool (with the done function) the reference connection is broken.

Sometimes it is useful to drop axes of length one (degenerate axes). Use the dropdeg argument if you want to do this.

The output mask is the combination (logical OR) of the default input pixel mask (if any) and the OTF mask. Any other input pixel masks will not be copied. Use function maskhandler if you need to copy other masks too.

See also the subimage function.

Example

- im := imagefromimage(outfile='image.small', infile='image.large', region=drm.quarter())

The specified region-of-interest takes a quarter by area of the first two axes of the image, and all pixels of other axes.