# Copyright 2014 Diamond Light Source Ltd.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
.. module:: hilbert_filter
:platform: Unix
:synopsis: A plugin to apply Hilbert filter horizontally for tomographic
reconstruction of phase gradient images.
.. moduleauthor:: Tunhe Zhou <tunhe.zhou@diamond.ac.uk>
"""
import numpy as np
import pyfftw.interfaces.scipy_fftpack as fft
from savu.plugins.filters.base_filter import BaseFilter
from savu.plugins.driver.cpu_plugin import CpuPlugin
from savu.plugins.utils import register_plugin
[docs]@register_plugin
class HilbertFilter(BaseFilter, CpuPlugin):
def __init__(self):
super(HilbertFilter, self).__init__('HilbertFilter')
self.filter1 = None
[docs] def pre_process(self):
self._setup_hilbert(*self.get_plugin_in_datasets()[0].get_shape())
def _setup_hilbert(self, height, width):
centerx = np.ceil(width / 2.0)
# Define the hilbert filter
filter1 = np.ones((height, width), dtype=np.float32)
filter1[:, 0:int(centerx)] = filter1[:, 0:int(centerx)] * (-1.0)
self.filter1 = filter1
def _hilbert(self, data):
pci = fft.ifftshift(
fft.fft2(fft.fftshift(np.float32(data)))) * self.filter1
fpci = fft.ifftshift(fft.ifft2(fft.fftshift(pci)))
return np.imag(fpci)
[docs] def process_frames(self, data):
proj = np.nan_to_num(data[0])
return self._hilbert(proj)
[docs] def get_max_frames(self):
return 'single'