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Next: coordsys.setreferencevalue - Function Up: coordsys - Tool Previous: coordsys.setreferencelocation - Function


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]





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