def chambolle_pock_tv_wavelets(data,
K,
Kadj,
W,
Lambda1,
Lambda2,
L=None,
n_it=100,
return_all=True,
x0=None):
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = 0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
p = proj_linf(p + sigma * gradient(x_tilde), Lambda1)
q = (q + sigma * K(x_tilde) - sigma * data) / (1.0 + sigma)
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q)
#
W.set_image(x)
W.forward()
W.soft_threshold(Lambda2, 0, 1)
wnorm1 = W.norm1()
W.inverse()
x = W.image
#
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda1 * tv + Lambda2 * wnorm1
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_tv_relaxed2(data,
K,
Kadj,
Lambda,
L=None,
rho=1.9,
tau=None,
n_it=100,
return_all=True,
x0=None):
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
if tau is None: tau = 1.0 / L
sigma = 1.0 / (tau * L * L)
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = 0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update primal variables
x_tilde = x + tau * div(p) - tau * Kadj(q)
# Update dual variables
p_tilde = proj_linf(p + sigma * gradient(2 * x_tilde - x), Lambda)
q_tilde = (q + sigma * K(2 * x_tilde - x) - sigma * data) / (1.0 +
sigma)
# Relaxed version
#~ x = rho*x_tilde + (1-rho)*x
#~ p = rho*p_tilde + (1-rho)*p
#~ q = rho*q_tilde + (1-rho)*q
x = x_tilde + (rho - 1) * (x_tilde - x)
p = p_tilde + (rho - 1) * (p_tilde - p)
q = q_tilde + (rho - 1) * (q_tilde - q)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_l1_wavelets(data,
W,
K,
Kadj,
Lambda,
L=None,
n_it=100,
return_all=True,
x0=None,
pos_constraint=False):
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = gradient(x)
q = 0 * data
x_tilde = 1.0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
# For isotropic TV, the prox is a projection onto the L2 unit ball.
# For anisotropic TV, this is a projection onto the L-infinity unit ball.
q = proj_linf(q + sigma * K(x_tilde) - sigma * data)
# Update primal variables
x_old = x
W.set_image(x - tau * Kadj(q))
W.forward()
W.soft_threshold(Lambda * tau, do_threshold_appcoeffs=1)
W.inverse()
x = W.image
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_tv_l2(data,
K,
Kadj,
U,
Uadj,
Lambda,
Lambda2,
L=None,
n_it=100,
return_all=True,
x0=None):
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
Lr = power_method(U, Uadj, data, 20)
L = sqrt(8. + L**2 + Lr**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
r = 0 * x
x_tilde = 0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
p = proj_linf(p + sigma * gradient(x_tilde), Lambda)
q = (q + sigma * K(x_tilde) - sigma * data) / (1.0 + sigma)
r = (r + sigma * U(x_tilde)) / (1.0 + sigma / Lambda2)
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q) - tau * Uadj(r)
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_tv2(data,
K,
Kadj,
Lambda,
L=None,
gamma=1.0,
theta=1.0,
n_it=100,
return_all=True,
x0=None):
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
#gamma = 0.5 # Should be the uniform convexity parameter of "F"
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = 0 * x
# theta = 1.0 # theta = 0 gives another fast algorithm
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
p = proj_linf(p + sigma * gradient(x_tilde), Lambda)
q = (q + sigma * K(x_tilde) - sigma * data) / (1.0 + sigma)
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q)
theta = 1. / sqrt(1. + 2 * gamma * tau)
tau = theta * tau
sigma = sigma / theta
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_l1_wavelets_precond(data,
W,
K,
Kadj,
Lambda,
n_it=100,
return_all=True,
x0=None,
pos_constraint=False):
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = x
theta = 1.0
# Compute the diagonal preconditioner "Sigma" for alpha=1
# Assuming K is a positive integral operator
Sigma_k = 1. / K(np.ones_like(x))
Sigma_grad = 1 / 2.0
Sigma = 1 / (1. / Sigma_k + 1. / Sigma_grad)
# Compute the diagonal preconditioner "Tau" for alpha = 1
# Assuming Kadj is a positive operator
Tau = 1. / (Kadj(np.ones_like(data)) + 2.)
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update primal variables
x_old = x
W.set_image(x - Tau * Kadj(q))
W.forward()
W.soft_threshold(Lambda, do_threshold_appcoeffs=1)
W.inverse()
x = W.image
# Update dual variables
q = proj_linf(q + Sigma_k * K(x + theta * (x - x_old)) -
Sigma_k * data) # <=
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_tv_precond(data,
K,
Kadj,
Lambda,
n_it=100,
return_all=True,
x0=None,
pos_constraint=False):
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = x
theta = 1.0
# Compute the diagonal preconditioner "Sigma" for alpha=1
# Assuming K is a positive integral operator
Sigma_k = 1. / K(np.ones_like(x))
Sigma_grad = 1 / 2.0
Sigma = 1 / (1. / Sigma_k + 1. / Sigma_grad)
# Compute the diagonal preconditioner "Tau" for alpha = 1
# Assuming Kadj is a positive operator
Tau = 1. / (Kadj(np.ones_like(data)) + 2.)
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update primal variables
x_old = x
x = x + Tau * div(p) - Tau * Kadj(q)
if pos_constraint:
x[x < 0] = 0
# Update dual variables
p = proj_linf(
p + Sigma_grad * gradient(x + theta * (x - x_old)), Lambda
) # For discrete gradient, sum|D_i,j| = 2 along lines or cols
q = (q + Sigma_k * K(x + theta * (x - x_old)) - Sigma_k * data) / (
1.0 + Sigma_k) # <=
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_deblur_tv(img,
G,
kern,
Lambda,
L=None,
n_it=100,
return_all=True,
bw=10):
"""
prototype
"""
if L is None: L = 2.83 # sqrt(8)
sigma = 1.0 / L
tau = 1.0 / L
theta = 1.0
x = 0 * img
x_tilde = 0 * x
y = 0 * x
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# y_{k+1} = prox_{sigma G^*} (y_k + sigma K xtilde_k)
y = _soft_thresh(y + sigma * gradient(x_tilde), Lambda * sigma)
# x_{k+1} = prox_{tau F} (x_n - tau K^* y_{k+1})
x_old = np.copy(x)
x = pinv_fourier(x + tau * div(y) + tau * G(img), kern, tau=tau, bw=bw)
# xtilde{k+1} = x_{k+1} + theta (x_{k+1} - x_k)
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(G(x) - img)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def normalize_sum(sino, tomo, rho0=1e2, rho1=1e3, nsteps=10, verbose=False):
"""
Normalize a sinogram with its sum along the angles:
sino_norm = sino - Sigma/rho
where Sigma is the sum of the sinogram along the angles, and rho some parameter.
"""
rhos = np.linspace(rho0, rho1, nsteps)
Sigma = sino.sum(axis=0)
tvs = []
for rho in rhos:
tvs.append(norm1(gradient(tomo.fbp(sino - Sigma / rho))))
if verbose: print("Rho = %e\t TV = %e" % (rho, tvs[-1]))
rho_opt = rhos[np.array(tvs).argmin()]
if verbose: print("Best rho: %e" % rho_opt)
return sino - Sigma / rho_opt
def chambolle_pock_tv(data,
K,
Kadj,
Lambda,
L=None,
n_it=100,
return_all=True,
x0=None,
pos_constraint=False):
'''
Chambolle-Pock algorithm for Total Variation regularization.
The following objective function is minimized : ||K x - d||_2^2 + Lambda TV(x)
Parameters
-----------
K : function
forward operator
Kadj : function
backward operator
Lambda : float
weight of the TV penalization (the higher Lambda, the more sparse is the solution)
L : float
norm of the operator [P, Lambda*grad] (see power_method)
n_it : int
number of iterations
return_all: bool
if True, an array containing the values of the objective function will be returned
x0: numpy.ndarray
initial solution estimate
'''
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = gradient(x)
q = 0 * data
x_tilde = 1.0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
# For isotropic TV, the prox is a projection onto the L2 unit ball.
# For anisotropic TV, this is a projection onto the L-infinity unit ball.
p = proj_linf(p + sigma * gradient(x_tilde), Lambda)
q = (q + sigma * K(x_tilde) - sigma * data) / (1.0 + sigma)
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q)
if pos_constraint:
x[x < 0] = 0
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_kl_tv(data,
K,
Kadj,
Lambda,
L=None,
n_it=100,
return_all=True,
x0=None):
'''
Chambolle-Pock algorithm for KL-TV.
The following objective function is minimized : KL(K x , d) + Lambda TV(x)
Where KL(x, y) is a modified Kullback-Leibler divergence.
This method might be more effective than L2-TV for Poisson noise.
K : forward operator
Kadj : backward operator
Lambda : weight of the TV penalization (the higher Lambda, the more sparse is the solution)
L : norm of the operator [P, Lambda*grad] (see power_method)
n_it : number of iterations
return_all: if True, an array containing the values of the objective function will be returned
x0: initial solution estimate
'''
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = 0 * x
theta = 1.0
#
O = np.ones_like(q)
#
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
tmp = q + sigma * K(x_tilde)
q = 0.5 * (O + tmp - np.sqrt((tmp - O)**2 + 4 * sigma * data))
tmp = p + sigma * gradient(x_tilde)
p = Lambda * (tmp) / np.maximum(Lambda, np.abs(tmp))
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q)
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x
def chambolle_pock_l1_tv(data,
K,
Kadj,
Lambda,
L=None,
n_it=100,
return_all=True,
x0=None):
'''
Chambolle-Pock algorithm for L1-TV.
The following objective function is minimized : ||K x - d||_1 + Lambda TV(x).
This method is recommended against L2-TV for noise with strong outliers (eg. salt & pepper).
Parameters
------------
K : forward operator
Kadj : backward operator
Lambda : weight of the TV penalization (the higher Lambda, the more sparse is the solution)
L : norm of the operator [P, Lambda*grad] (see power_method)
n_it : number of iterations
return_all: if True, an array containing the values of the objective function will be returned
x0: initial solution estimate
'''
if L is None:
print(
"Warn: chambolle_pock(): Lipschitz constant not provided, computing it with 20 iterations"
)
L = power_method(K, Kadj, data, 20)
L = sqrt(8. + L**2) * 1.2
print("L = %e" % L)
sigma = 1.0 / L
tau = 1.0 / L
if x0 is not None:
x = x0
else:
x = 0 * Kadj(data)
p = 0 * gradient(x)
q = 0 * data
x_tilde = 0 * x
theta = 1.0
if return_all: en = np.zeros(n_it)
for k in range(0, n_it):
# Update dual variables
p = proj_l2(p + sigma * gradient(x_tilde), Lambda)
q = proj_linf(
q + sigma * K(x_tilde) - sigma * data
) # Here the projection onto the l-infinity ball is absolutely required !
# Update primal variables
x_old = x
x = x + tau * div(p) - tau * Kadj(q)
x_tilde = x + theta * (x - x_old)
# Calculate norms
if return_all:
fidelity = 0.5 * norm2sq(K(x) - data)
tv = norm1(gradient(x))
energy = 1.0 * fidelity + Lambda * tv
en[k] = energy
if (k % 10 == 0): # TODO: more flexible
print("[%d] : energy %e \t fidelity %e \t TV %e" %
(k, energy, fidelity, tv))
if return_all: return en, x
else: return x