1.1.1.0 image.maskhandler

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image.maskhandler - Function

1.1.1 Handle pixel masks

Description

This function is used to manage or handle pixel masks . A CASA image may contain zero, one or more pixel masks. Any of these masks can be designated the default pixel mask. The default mask is acted upon by CASA applications. For example, if you ask for statistics from an image, pixels which are masked as bad (F) will be excluded from the calculations.

This function has an argument (op) that specifies the behaviour. In all cases, you can shorten the operation string to three characters. It is not the job of this function to modify the values of masks.

default - this retrieves the name of the default pixel mask as the return value of the function call.
get - this retrieves the name(s) of the existing pixel masks as the return value of the function call (string or vector of strings).
set - this lets you change the default pixel mask to that given by the name argument. If name is empty, then the default mask is unset (i.e. an all good mask is effectively applied).
delete - this lets you delete the pixel masks specified by the name argument. To delete more than one mask, name can be a vector of strings. Any supplied pixel mask name that does not exist is silently ignored.
rename - this lets you rename the mask specified by name[0] to name[1]. Thus the name argument must be a vector of length 2.
copy - this lets you copy a mask to another in the same image, or copy a mask from another image into this image. Thus the name argument must be a vector of length 2.
For the first case, the first element of name must be the name of the mask to copy, and the second element must be the name of the pixel mask to which it will be copied.
For the second case, the first element of name must be the name of the input image and pixel mask with a colon delimiter (e.g. hcn:mask2). The second element must be the name of the pixel mask to which the input pixel mask will be copied.

Use the summary function to see the available pixel masks. You can do this either via the logger display, or via the returned record, which contains the mask names. In the logger display, any pixel mask which is not the default mask is listed in square brackets. If a default mask is set, it is listed first, and is not enclosed in square brackets.

Arguments


Inputs
op	The operation. One of ’set’, ’delete’, ’rename’, ’get’, ’copy’ or ’default’
	allowed:	string
	Default:	default
name	Name of mask or masks.
	allowed:	stringArray
	Default:

Returns
stringArray

Example

"""
#
print "\t----\t maskhandler Ex 1 \t----"
ia.maketestimage(’g1.app’, overwrite=true)
ia.calcmask(’T’, name=’mask1’)
ia.close()
ia.maketestimage(’myimage’, overwrite=true)
ia.calcmask(’T’)                         # Create some masks
ia.calcmask(’T’, name=’mask1’)
ia.calcmask(’T’, name=’mask2’)
names = ia.maskhandler(’get’)            # Get the mask names
print names
#[’mask0’, ’mask1’, ’mask2’]
name = ia.maskhandler(’default’)         # Get the default mask name
print name
#mask2
ia.maskhandler(’set’, [’mask1’])         # Make ’mask1’ the default mask
ia.maskhandler(’set’, [’’])              # Unset the default mask
ia.maskhandler(’delete’, [’mask1’])      # Delete ’mask1’
ia.calcmask(’T’, name=’mask1’)           # Make another ’mask1’
ia.maskhandler(’delete’, [’mask0’, ’mask1’])# Delete ’mask0’ and ’mask1’
ia.calcmask(’T’, name=’mask1’)
ia.maskhandler(’rename’, [’mask1’, ’mask0’])# Rename ’mask1’ to ’mask0’

# Copy ’mask1’ from image ’g1.app’  to ’mask10’ in image ’myimage’
ia.maskhandler(’copy’, [’g1.app:mask1’, ’mask10’])
ia.removefile(’g1.app’)                  # Cleanup
ia.close()
#
"""

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