Common Imaging API

Use the factory and shared interface for backend-switched imaging. See Imaging Backend Selection for examples and current adapter limitations.

Interface and factory

class ImageSpec(npix: int, cellsize_arcsec: float, phase_centre_deg: Tuple[float, float], polarisation: str = 'I', nchan: int = 1)

Minimal imaging parameters shared across backends.

property cellsize_radians: float: Return the pixel scale in radians.

class Imager

Backend-agnostic imaging interface.

abstractmethod invert(vis: Visibility, image_spec: ImageSpec) → tuple[Image, Image]: Grid visibilities into dirty image and PSF images.

abstractmethod restore(model_or_dirty: Image, psf: Image) → Image: Return a restored image using the provided PSF.

class ImagingBackend(*values)

Supported imaging backends.

SDP = 'sdp'

WSCLEAN = 'wsclean'

parse_imaging_backend(backend: str | ImagingBackend | None = None) → ImagingBackend

get_imager(backend: str | ImagingBackend | None = None, *, config: SdpImagerConfig | WscleanBackendConfig | None = None) → Imager

Direct-imager base classes

These lower-level classes support the direct OSKAR dirty imager and the direct WSClean implementation. They are not the backend-neutral Imager interface. Their imaging_cellsize parameter uses radians; ImageSpec uses arcseconds.

class DirtyImagerConfig(imaging_npixel: int, imaging_cellsize: float, combine_across_frequencies: bool = True)

Base class for the config / parameters of a dirty imager.

Contains basic parameters common across all dirty imagers. Inherit and add parameters specific to a dirty imager implementation.

imaging_npixel

Image size

Type:: int

imaging_cellsize

Scale of a pixel in radians

Type:: float

combine_across_frequencies

Whether or not to combine images across all frequency channels into one image. Defaults to True.

Type:: bool

__init__(imaging_npixel: int, imaging_cellsize: float, combine_across_frequencies: bool = True) → None

class DirtyImager

Abstract base class for a dirty imager.

A dirty imager creates dirty images from visibilities.

abstractmethod create_dirty_image(visibility: Visibility, /, *, output_fits_path: Path | str | None = None) → Image

Creates a dirty image from a visibility.

Parameters:

visibility – Visibility object from which to create the dirty image. Contains the visibilities of an observation.
output_fits_path – Path to write the dirty image to. Example: /tmp/dirty.fits. If None, will be set to a temporary directory and a default file name. Defaults to None.

Returns:

Dirty image

Return type:

Image

class ImageCleanerConfig(imaging_npixel: int, imaging_cellsize: float)

Base class for the config / parameters of an image cleaner.

Contains basic parameters common across all image cleaners. Inherit and add parameters specific to an image cleaner implementation.

imaging_npixel

Image size

Type:: int

imaging_cellsize

Scale of a pixel in radians

Type:: float

__init__(imaging_npixel: int, imaging_cellsize: float) → None

class ImageCleaner

Abstract base class for an image cleaner.

An image cleaner creates clean images from dirty images or directly from visibilities, in that case including the dirty imaging process.

abstractmethod create_cleaned_image(visibility: Visibility, /, *, dirty_fits_path: Path | str | None = None, output_fits_path: Path | str | None = None) → Image

Creates a clean image from a dirty image or from visibilities.

Parameters:

visibility – Visibility from which a clean image should be created.
dirty_fits_path – Path to dirty image FITS file that should be reused to create a clean image. If None, dirty image will be created first from the visibilities. Defaults to None.
output_fits_path – Path to write the clean image to. Example: /tmp/restored.fits. If None, will be set to a temporary directory and a default file name. Defaults to None.

Returns:

Clean image

Return type:

Image