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coordsys.setreferencepixel - Function

	Package	general
	Module	images
	Tool	coordsys

Set the reference pixel

Synopsis
setreferencepixel(type, value)

Arguments

type	in	Which coordinate type ?
		Allowed:	String from "direction", "stokes", "spectral", "linear", "tabular" or unset
		Default:	All
value	in	Reference pixel
		Allowed:	Vector of double

Returns
T or fail

Description

Each axis associated with the Coordinate System has a reference value, reference pixel and an increment (per pixel). These are used in the mapping from pixel to world coordinate.

This function (short-hand name srp) allows you to set a new reference pixel. You should not do this on "stokes" axes unless you are an adept or a big risk taker.

You can set the reference pixel either for all axes (type=unset) or for just the axes associated with a particular coordinate type.

Bear in mind, that if your Coordinate System came from a real image, then the reference pixel is special and you should not change it for Direction Coordinates.

You can recover the current reference pixel with function referencepixel.

Example

- cs := coordsys(spectral=T, linear=2)
- cs.setreferencepixel(value=[1.0, 2.0, 3.0])
- cs.referencepixel()
[1 2 3]
-
- cs.setreferencepixel('lin', [-1, -1])
- cs.referencepixel()
[1 -1 -1]