1.1.1.0 image.hanning

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image.hanning - Function

1.1.1 Convolve one axis of image with a Hanning kernel
Description

This function performs Hanning convolution (z[i] = 0.25 * y[i - 1] + 0.5 * y[i] + 0.25 * y[i + 1]) of one axis of an image. The convolution is done in the image domain (i.e., not with an FFT). You can optionally drop every other pixel on output. If you do this, the first output pixel is centered on the second input pixel.

If outfile is given, the image is written to the specified disk file. If outfile is unset, the Image tool is associated with a temporary image. This temporary image may be in memory or on disk, depending on its size. When you destroy the on-the-fly Image tool created by this function (with the done function) this temporary image is deleted.

Masked pixels will be assigned the value 0.0 before convolution. 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 other convolution functions convolve2d, sepconvolve and convolve.

Arguments


Inputs
outfile	Output image file name. Default is unset.
	allowed:	string
	Default:
region	Region of interest. Default is whole image.
	allowed:	any
	Default:	record
mask	OTF mask, Boolean LEL expression or mask region. Default is none.
	allowed:	any
	Default:	variant
axis	Axis to convolve. Default is spectral axis if there is one
	allowed:	int
	Default:	-10
drop	Drop every other pixel on output?
	allowed:	bool
	Default:	true
overwrite	Overwrite (unprompted) pre-existing output file?
	allowed:	bool
	Default:	false
async	Run asynchronously?
	allowed:	bool
	Default:	false

Returns
casaimage

Example

"""
print "\t----\t hanning Ex 1 \t----"
ia.fromshape(’x’, shape=[64,64,128], overwrite=true)
print ia.summary()
im2 = ia.hanning(outfile=’x.hann’)
print im2.summary()
im2.done(remove=T)
ia.close()
#
"""

This would Hanning smooth the spectral axis of the image associated with the default image tool ia, if there is one. Every other pixel on the convolution axis is dropped on output, by default.

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