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image.fft - Function

	Package	general
	Module	images
	Tool	image

FFT the image

Synopsis
fft(real, imag, amp, phase, axes, region, mask)

Arguments

real	in	Output real image file name
		Allowed:	String
imag	in	Output imaginary image file name
		Allowed:	String
amp	in	Output amplitude image file name
		Allowed:	String
phase	in	Output phase image file name
		Allowed:	String
axes	in	Specify pixel axes to FFT
		Allowed:	Vector of integers
		Default:	Sky plane(s)
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

Returns
T or fail

Description

This function fast Fourier Transforms the image to the Fourier plane. If you leave axes unset, then the sky plane of the image (if there is one) is transformed. Otherwise, you can specify which axes you wish to transform. Note that if you specify a sky axis, you must specify both of them.

You specify which form you wish to see the result in by specifying the desired output image file name(s). At some point, an output complex image will also be allowed (when the Image tool can deal with it).

Before the FFT is taken, any masked pixels are replaced by zero. 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.

Example

- myim := image('gc.small')
- myim.fft(real='r.im', amp='a.im')

This transforms only the sky plane(s). The real and amplitude images only are written out.

Example

myim := image('gc.small')
myim.fft(amp='amp.im', phase='p.im', axes=[3])

This transforms only the third axis of the image. The amplitude and phase images only are written out. estimate.