opticam.align

Functions

find_translation(reference_coords, coords)	Find the translation that maps reference_coords onto coords. An advantage of this over
align_batch(batch, reference_image_shape, ...)	Align an image based on some reference coordinates.
valid_transform(file, transform, rotation_limit, ...)	Find whether a transform is valid given some transform limits.

Module Contents

opticam.align.find_translation(reference_coords, coords)

Find the translation that maps reference_coords onto coords. An advantage of this over astroalign.find_transform() is that it requires fewer sources, however it is therefore more prone to errors. In general, astroalign.find_transform() should be used, but find_translation() is available if there are too few sources for astroalign.find_transform().

Parameters

reference_coordsNDArray

The reference source coordinates.

coordsNDArray

The source coordinates.

Returns

SimilarityTransform

The transformation matrix that maps coords onto reference_coords.

Parameters:

• reference_coords (numpy.typing.NDArray)

• coords (numpy.typing.NDArray)

Return type:

skimage.transform.SimilarityTransform

opticam.align.align_batch(batch, reference_image_shape, reference_coords, transform_type, rotation_limit, scale_limit, translation_limit, n_alignment_sources, gains, flat_corrector, rebin_factor, remove_cosmic_rays, background, finder, threshold, logger)

Align an image based on some reference coordinates.

Parameters

file: str

The file path.

reference_imageNDArray

The reference image.

reference_coordsNDArray

The source coordinates in the reference image.

transform_typeLiteral[‘affine’, ‘translation’]

The type of transform to use for image alignment.

rotation_limitfloat | None

The maximum rotation limit (in degrees) for image alignment.

scale_limitfloat | None

The maximum scaling limit for image alignment.

translation_limitList[float] | None

The maximum translation limit for image alignment.

n_alignment_sourcesint

The (maximum) number of sources to use for image alignment.

Returns

Tuple[List[float], float, float]

The transform parameters, background median, and background RMS.

Parameters:

• batch (List[str])

• reference_image_shape (Tuple[int])

• reference_coords (numpy.typing.NDArray)

• transform_type (Literal['affine', 'translation'])

• rotation_limit (float | None)

• scale_limit (float | None)

• translation_limit (List[float] | None)

• n_alignment_sources (int)

• gains (Dict[str, float])

• flat_corrector (opticam.correctors.flat_field_corrector.FlatFieldCorrector | None)

• rebin_factor (int)

• remove_cosmic_rays (bool)

• background (opticam.background.global_background.BaseBackground)

• finder (opticam.finders.DefaultFinder)

• threshold (float | int)

• logger (logging.Logger)

Return type:

Tuple[numpy.typing.NDArray, Dict[str, float], Dict[str, float], Dict[str, float]]

opticam.align.valid_transform(file, transform, rotation_limit, scale_limit, translation_limit, logger)

Find whether a transform is valid given some transform limits.

Parameters

filestr

The file being transformed.

transformSimilarityTransform

The transform.

rotation_limitfloat | None

The rotation limit.

scale_limitfloat | None

The scale limit.

translation_limitList[float] | None

The translation limit.

Returns

bool

Whether the transform is valid.

Parameters:

• file (str)

• transform (skimage.transform.SimilarityTransform)

• rotation_limit (float | None)

• scale_limit (float | None)

• translation_limit (List[float] | None)

• logger (logging.Logger)

Return type:

bool