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| -rw-r--r-- | Wrappers/Python/demos/PDHG_examples/PDHG_TV_Denoising_Gaussian_3D.py | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/Wrappers/Python/demos/PDHG_examples/PDHG_TV_Denoising_Gaussian_3D.py b/Wrappers/Python/demos/PDHG_examples/PDHG_TV_Denoising_Gaussian_3D.py new file mode 100644 index 0000000..dbf81e2 --- /dev/null +++ b/Wrappers/Python/demos/PDHG_examples/PDHG_TV_Denoising_Gaussian_3D.py @@ -0,0 +1,178 @@ +#======================================================================== +# Copyright 2019 Science Technology Facilities Council +# Copyright 2019 University of Manchester +# +# This work is part of the Core Imaging Library developed by Science Technology +# Facilities Council and University of Manchester +# +# 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.txt +# +# 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. +# +#========================================================================= +""" + +Total Variation (3D) Denoising using PDHG algorithm: + + +Problem: min_{x} \alpha * ||\nabla x||_{2,1} + \frac{1}{2} * || x - g ||_{2}^{2} + + \alpha: Regularization parameter + + \nabla: Gradient operator + + g: Noisy Data with Gaussian Noise + + Method = 0 ( PDHG - split ) : K = [ \nabla, + Identity] + + + Method = 1 (PDHG - explicit ): K = \nabla + +""" + +from ccpi.framework import ImageData, ImageGeometry + +import matplotlib.pyplot as plt + +from ccpi.optimisation.algorithms import PDHG + +from ccpi.optimisation.operators import BlockOperator, Identity, Gradient +from ccpi.optimisation.functions import ZeroFunction, L2NormSquared, \ + MixedL21Norm, BlockFunction + +from skimage.util import random_noise + +# Create phantom for TV Gaussian denoising +import timeit +import os +from tomophantom import TomoP3D +import tomophantom + +print ("Building 3D phantom using TomoPhantom software") +tic=timeit.default_timer() +model = 13 # select a model number from the library +N = 64 # Define phantom dimensions using a scalar value (cubic phantom) +path = os.path.dirname(tomophantom.__file__) +path_library3D = os.path.join(path, "Phantom3DLibrary.dat") + +#This will generate a N x N x N phantom (3D) +phantom_tm = TomoP3D.Model(model, N, path_library3D) + +# Create noisy data. Add Gaussian noise +ig = ImageGeometry(voxel_num_x=N, voxel_num_y=N, voxel_num_z=N) +ag = ig +n1 = random_noise(phantom_tm, mode = 'gaussian', mean=0, var = 0.001, seed=10) +noisy_data = ImageData(n1) + +sliceSel = int(0.5*N) +plt.figure(figsize=(15,15)) +plt.subplot(3,1,1) +plt.imshow(noisy_data.as_array()[sliceSel,:,:],vmin=0, vmax=1) +plt.title('Axial View') +plt.colorbar() +plt.subplot(3,1,2) +plt.imshow(noisy_data.as_array()[:,sliceSel,:],vmin=0, vmax=1) +plt.title('Coronal View') +plt.colorbar() +plt.subplot(3,1,3) +plt.imshow(noisy_data.as_array()[:,:,sliceSel],vmin=0, vmax=1) +plt.title('Sagittal View') +plt.colorbar() +plt.show() + + +# Regularisation Parameter +alpha = 0.05 + +method = '0' + +if method == '0': + + # Create operators + op1 = Gradient(ig) + op2 = Identity(ig, ag) + + # Create BlockOperator + operator = BlockOperator(op1, op2, shape=(2,1) ) + + # Create functions + + f1 = alpha * MixedL21Norm() + f2 = 0.5 * L2NormSquared(b = noisy_data) + f = BlockFunction(f1, f2) + + g = ZeroFunction() + +else: + + # Without the "Block Framework" + operator = Gradient(ig) + f = alpha * MixedL21Norm() + g = 0.5 * L2NormSquared(b = noisy_data) + + +# Compute operator Norm +normK = operator.norm() + +# Primal & dual stepsizes +sigma = 1 +tau = 1/(sigma*normK**2) + +# Setup and run the PDHG algorithm +pdhg = PDHG(f=f,g=g,operator=operator, tau=tau, sigma=sigma, memopt=True) +pdhg.max_iteration = 2000 +pdhg.update_objective_interval = 200 +pdhg.run(2000, verbose = True) + + +#%% +fig, axes = plt.subplots(nrows=2, ncols=3, figsize=(10, 8)) +fig.suptitle('TV Reconstruction',fontsize=20) + + +plt.subplot(2,3,1) +plt.imshow(noisy_data.as_array()[sliceSel,:,:],vmin=0, vmax=1) +plt.axis('off') +plt.title('Axial View') + +plt.subplot(2,3,2) +plt.imshow(noisy_data.as_array()[:,sliceSel,:],vmin=0, vmax=1) +plt.axis('off') +plt.title('Coronal View') + +plt.subplot(2,3,3) +plt.imshow(noisy_data.as_array()[:,:,sliceSel],vmin=0, vmax=1) +plt.axis('off') +plt.title('Sagittal View') + + +plt.subplot(2,3,4) +plt.imshow(pdhg.get_output().as_array()[sliceSel,:,:],vmin=0, vmax=1) +plt.axis('off') +plt.subplot(2,3,5) +plt.imshow(pdhg.get_output().as_array()[:,sliceSel,:],vmin=0, vmax=1) +plt.axis('off') +plt.subplot(2,3,6) +plt.imshow(pdhg.get_output().as_array()[:,:,sliceSel],vmin=0, vmax=1) +plt.axis('off') +im = plt.imshow(pdhg.get_output().as_array()[:,:,sliceSel],vmin=0, vmax=1) + + +fig.subplots_adjust(bottom=0.1, top=0.9, left=0.1, right=0.8, + wspace=0.02, hspace=0.02) + +cb_ax = fig.add_axes([0.83, 0.1, 0.02, 0.8]) +cbar = fig.colorbar(im, cax=cb_ax) + + +plt.show() + |