PClip

PClip(frac=-0.5, sigma=3.0, nkeep=1, grow=None)

IRAF-style percentile clipping.

Parameters

frac : float = -0.5

IRAF pclip value. Values with abs(frac) < 1 are converted to an integer sorted-rank offset using half of the input image count.

sigma : float or tuple of float = 3.0

User-supplied lower and upper clipping multipliers applied to the pclip-estimated spread.

nkeep : int = 1

Minimum number of unmasked samples to retain after pclip rejection.

grow : float or None = None

Optional radius in pixels used to grow mask_rej spatially after rejection. Axis 0 is the stack axis and is never grown across. None disables growth and skips the extra calculation.

Attributes

Name	Description
frac	Convert a string or number to a floating-point number, if possible.
nkeep	int([x]) -> integer
sigma	Convert a string or number to a floating-point number, if possible.

Methods

Name	Description
apply	Apply PClip to an image stack.

apply

PClip.apply(arr, mask=None, *, validate=True)

Apply PClip to an image stack.

Parameters

arr : (ndarray, shape(N, *spatial))

Image stack. Inputs with more than 3 dimensions are flattened internally; output shapes match the trailing spatial dimensions of the input.

mask : ndarray of bool = None

Input mask; True means already masked. Must have the same shape as arr before any internal flattening.

validate : bool = True

If True, validate inputs before calling the kernel.

Returns

: mask_rej, std, low, upp, nit, output_flags : tuple of ndarray

Rejection mask and diagnostics from :func:imcombiners.kernels.pclip. std is the per-pixel spread used by sigma/CCD clipping and None for rejection algorithms without a spread diagnostic.