# -*- coding: utf-8 -*-
##########################################################################
# pySAP - Copyright (C) CEA, 2017 - 2018
# Distributed under the terms of the CeCILL-B license, as published by
# the CEA-CNRS-INRIA. Refer to the LICENSE file or to
# http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.html
# for details.
##########################################################################
"""DENOISE.
This module defines a function to perform galaxy image denoising using
wavelets.
"""
import numpy as np
from modopt.signal.noise import thresh
from pysap.plugins.astro.denoising.noise import noise_est, sigma_scales
from pysap.plugins.astro.denoising.wavelet import decompose, recombine
[docs]def denoise(image, n_scales=4):
"""Denoise.
This function provides a denoised version of the input image.
Parameters
----------
image : numpy.ndarray
Input image
n_scales : int
Number of wavelet scales to use
Returns
-------
numpy.ndarray
Denoised image
Examples
--------
>>> import numpy as np
>>> from astro.denoising.denoise import denoise
>>> data = np.arange(9).reshape((3, 3)) * 0.1
>>> denoise(data)
array([[0.15000001, 0.21250004, 0.27500001],
[0.39121097, 0.40000004, 0.4087891 ],
[0.52500004, 0.58750004, 0.65000004]])
"""
sigma_est_scales = sigma_scales(noise_est(image), n_scales)
weights = (
np.array([4] + [3] * sigma_est_scales[:-1].size) * sigma_est_scales
)
data_decomp = decompose(image, n_scales)
data_thresh = np.vstack([
thresh(data_decomp[:-1].T, weights).T,
data_decomp[-1, None]
])
return recombine(data_thresh)
