def test_density_sampling():
import os
import os.path
import numpy as np
import experiments.registration.dataset_info as info
import nibabel as nib
import dipy.align.metrics as metrics
import dipy.align.imwarp as imwarp
from dipy.align import VerbosityLevels
from experiments.registration.rcommon import getBaseFileName, decompose_path, readAntsAffine
from dipy.fixes import argparse as arg
from experiments.registration.evaluation import (
compute_densities,
sample_from_density,
create_ss_de,
create_ss_mode,
create_ss_median,
create_ss_mean,
)
from experiments.registration.splines import CubicSpline
import dipy.viz.regtools as rt
i1_name = info.get_ibsr(1, "strip")
i1_nib = nib.load(i1_name)
i1 = i1_nib.get_data().squeeze()
mask = (i1 > 0).astype(np.int32)
wt1_name = "warpedDiff_brainweb_t2_strip_IBSR_01_ana_strip.nii.gz"
wt1_nib = nib.load(wt1_name)
wt1 = wt1_nib.get_data().squeeze()
rt.overlay_slices(i1, wt1)
nbins = 100
densities = compute_densities(i1.astype(np.int32), wt1.astype(np.float64), nbins, mask)
figure()
imshow(densities)
# Compare different estimators
ss_sampled = create_ss_de(i1.astype(np.int32), densities)
ss_mode = create_ss_mode(i1.astype(np.int32), densities)
ss_median = create_ss_median(i1.astype(np.int32), densities)
ss_mean = create_ss_mean(i1.astype(np.int32), densities)
rt.overlay_slices(ss_sampled, i1)
rt.overlay_slices(ss_mode, i1)
rt.overlay_slices(ss_median, i1)
rt.overlay_slices(ss_mean, i1)
s1 = ss_sampled[:, ss_sampled.shape[1] // 2, :].T
s2 = ss_mode[:, ss_mode.shape[1] // 2, :].T
s3 = ss_median[:, ss_median.shape[1] // 2, :].T
s4 = ss_mean[:, ss_mean.shape[1] // 2, :].T
slices = [[s1, s2], [s3, s4]]
titles = [["Sampled", "Mode"], ["Median", "Mean"]]
fig, ax = plt.subplots(2, 2)
fig.set_facecolor("white")
for ii, a_row in enumerate(ax):
for jj, a in enumerate(a_row):
a.set_axis_off()
a.imshow(slices[ii][jj], cmap=cm.gray, origin="lower")
a.set_title(titles[ii][jj])
# Fit densities with splines in a regular grid
f = densities[100]
kspacing = 1 # Number of grid cells between spline knots
spline = CubicSpline(kspacing)
coef = spline.fit_to_data(f)
# Check fit
fit = spline.evaluate(coef, nbins)
figure()
plot(f)
plot(fit)
# And the derivative
df = spline.evaluate(coef, nbins, 1)
figure()
plot(f)
plot(df)
fit = np.zeros_like(densities)
for i in range(densities.shape[0]):
coef = spline.fit_to_data(densities[i])
fit[i, :] = spline.evaluate(coef, nbins)
fig = plt.figure()
ax = fig.add_subplot(1, 2, 1)
ax.imshow(densities)
ax = fig.add_subplot(1, 2, 2)
ax.imshow(fit)
def create_semi_synthetic(params):
r""" Create semi-synthetic image using real_mod1 as anatomy and tmp_mod2 template as intensity model
Template tmp_mod1 is registered towards real_mod1 (which are assumed of the same modality) using SyN-CC.
The transformation is applied to template tmp_mod2 (which is assumed to be perfectly aligned with tmp_mod1).
The transfer function is computed from real_mod1 to warped tmp_mod2 and applied to real_mod1.
"""
real_mod1 = params.real
base_fixed = getBaseFileName(real_mod1)
tmp_mod1 = params.template
prealign_name = params.prealign
tmp_mod2_list = [os.path.join(params.warp_dir, name) for name in os.listdir(params.warp_dir)]
tmp_mod2_list = [tmp_mod1] + tmp_mod2_list
# Check if all warpings are already done
warp_done = os.path.isfile("mask_" + base_fixed + ".nii.gz")
if warp_done:
for tmp_mod2 in tmp_mod2_list:
base_moving = getBaseFileName(tmp_mod2)
wname = "warpedDiff_" + base_moving + "_" + base_fixed
if real_mod1[-3:] == "img": # Analyze
wname += ".img"
else:
wname += ".nii.gz"
if not os.path.isfile(wname):
warp_done = False
break
# Load input images
real_nib = nib.load(real_mod1)
real_aff = real_nib.get_affine()
real = real_nib.get_data().squeeze()
if real_mod1[-3:] == "img": # Analyze: move reference from center to corner
offset = real_aff[:3, :3].dot(np.array(real.shape) // 2)
real_aff[:3, 3] += offset
t_mod1_nib = nib.load(tmp_mod1)
t_mod1_aff = t_mod1_nib.get_affine()
t_mod1 = t_mod1_nib.get_data().squeeze()
if tmp_mod1[-3:] == "img": # Analyze: move reference from center to corner
offset = t_mod1_aff[:3, :3].dot(np.array(t_mod1.shape) // 2)
t_mod1_aff[:3, 3] += offset
# Load pre-align matrix
print("Pre-align:", prealign_name)
if not prealign_name:
prealign = np.eye(4)
else:
if real_mod1[-3:] == "img": # Analyze
ref_coordinate_system = "LAS"
else: # DICOM
ref_coordinate_system = "LPS"
if tmp_mod1[-3:] == "img": # Analyze
tgt_coordinate_system = "LAS"
else: # DICOM
tgt_coordinate_system = "LPS"
prealign = readAntsAffine(prealign_name, ref_coordinate_system, tgt_coordinate_system)
# Configure CC metric
sigma_diff = 1.7
radius = 4
similarity_metric = metrics.CCMetric(3, sigma_diff, radius)
# Configure optimizer
opt_iter = [100, 100, 50]
step_length = 0.25
opt_tol = 1e-5
inv_iter = 20
inv_tol = 1e-3
ss_sigma_factor = 0.2
if not warp_done:
syn = imwarp.SymmetricDiffeomorphicRegistration(
similarity_metric, opt_iter, step_length, ss_sigma_factor, opt_tol, inv_iter, inv_tol, callback=None
)
# Run registration
syn.verbosity = VerbosityLevels.DEBUG
mapping = syn.optimize(real, t_mod1, real_aff, t_mod1_aff, prealign)
# Save the warped template (so we can visually check the registration result)
warped = mapping.transform(t_mod1)
base_moving = getBaseFileName(tmp_mod1)
oname = "warpedDiff_" + base_moving + "_" + base_fixed
if real_mod1[-3:] == "img": # Analyze
oname += ".img"
else:
oname += ".nii.gz"
real[...] = warped[...]
real_nib.to_filename(oname)
mask = (t_mod1 > 0).astype(np.int32)
wmask = mapping.transform(mask, "nearest")
wmask_nib = nib.Nifti1Image(wmask, t_mod1_aff)
wmask_nib.to_filename("mask_" + base_fixed + ".nii.gz")
else:
wmask_nib = nib.load("mask_" + base_fixed + ".nii.gz")
wmask = wmask_nib.get_data().squeeze()
# Compute and save the semi-synthetic images in different modalities
for tmp_mod2 in tmp_mod2_list:
print("Warping: " + tmp_mod2)
t_mod2_nib = nib.load(tmp_mod2)
t_mod2_aff = t_mod2_nib.get_affine()
t_mod2 = t_mod2_nib.get_data().squeeze()
base_moving = getBaseFileName(tmp_mod2)
oname = base_moving + "_" + base_fixed
if real_mod1[-3:] == "img": # Analyze
oname += ".img"
else:
oname += ".nii.gz"
if not warp_done:
# Save warped image
warped = mapping.transform(t_mod2)
wnib = nib.Nifti1Image(warped, t_mod2_aff)
wnib.to_filename("warpedDiff_" + oname)
else:
wnib = nib.load("warpedDiff_" + oname)
warped = wnib.get_data().squeeze()
real_nib = nib.load(real_mod1)
real = real_nib.get_data().squeeze()
use_density_estimation = True
nbins = 100
if use_density_estimation:
print("Using density sampling.")
oname = "ssds_" + oname
# Compute marginal distributions
densities = np.array(compute_densities(real.astype(np.int32), warped.astype(np.float64), nbins, wmask))
# Sample the marginal distributions
real[...] = create_ss_de(real.astype(np.int32), densities)
else:
print("Using mean transfer.")
oname = "ssmt_" + oname
# Compute transfer function
means, vars = get_mean_transfer(real, warped)
# Apply transfer to real
real[...] = means[real]
# Save semi_synthetic
real_nib.to_filename(oname)
