PointSpreadFunction#

class lsst.images.psfs.PointSpreadFunction#

Bases: ABC

Base class for point-spread function models.

Attributes Summary

`bounds`	The region where this PSF model is valid.
`kernel_bbox`	Bounding box of all images returned by `compute_kernel_image`.

Methods Summary

`compute_kernel_image`(*, x, y)	Evaluate the PSF model into an image suitable for convolution.
`compute_stellar_bbox`(*, x, y)	Return the bounding box of the image that would be returned by `compute_stellar_image`.
`compute_stellar_image`(*, x, y)	Evaluate the PSF model into an image suitable for comparison with the image of an astrophysical point source.
`from_legacy`(legacy_psf, bounds)	Make a PSF object from a legacy `lsst.afw.detection.Psf` instance.

Attributes Documentation

bounds#: The region where this PSF model is valid.

kernel_bbox#: Bounding box of all images returned by compute_kernel_image.

Methods Documentation

abstract compute_kernel_image(*, x: float, y: float) → Image#

Evaluate the PSF model into an image suitable for convolution.

Parameters#

x: Column position coordinate to evaluate at.
y: Row position coordinate to evaluate at.

Returns#

Image: An image of the PSF, centered on the center of the center pixel, which is defined to be (0, 0) by the image’s origin.

abstract compute_stellar_bbox(*, x: float, y: float) → Box#

Return the bounding box of the image that would be returned by compute_stellar_image.

Parameters#

x: Column position coordinate to evaluate at.
y: Row position coordinate to evaluate at.

Returns#

Box: The bounding box of the image that would be returned by compute_stellar_image at the given point.

abstract compute_stellar_image(*, x: float, y: float) → Image#

Evaluate the PSF model into an image suitable for comparison with the image of an astrophysical point source.

Parameters#

x: Column position coordinate to evaluate at.
y: Row position coordinate to evaluate at.

Returns#

Image: An image of the PSF, centered on the given coordinates, just like the postage stamp of a star would be.

classmethod from_legacy(legacy_psf: Any, bounds: Bounds) → PointSpreadFunction#

Make a PSF object from a legacy lsst.afw.detection.Psf instance.

Parameters#

legacy_psf: Legacy PSF object.
bounds: The region where this PSF model is valid.

Returns#

PointSpreadFunction: A PointSpreadFunction instance.

Notes#

This base class method is a factory dispatch function that automatically selects the right PointSpreadFunction subclass to use. When that is already known, a subclass from_legacy method can be called instead.