3D X-ray Transform Comparison

This example shows how to define a SCICO native 3D X-ray transform using ASTRA toolbox conventions and vice versa.

import numpy as np

import jax
import jax.numpy as jnp

import scico.linop.xray.astra as astra
from scico import plot
from scico.examples import create_block_phantom
from scico.linop.xray import XRayTransform3D
from scico.util import ContextTimer, Timer
plot.config_notebook_plotting()

Create a ground truth image and set detector dimensions.

N = 64
# use rectangular volume to check whether axes are handled correctly
in_shape = (N + 1, N + 2, N + 3)
x = create_block_phantom(in_shape)
x = jnp.array(x)

# use rectangular detector to check whether axes are handled correctly
out_shape = (N, N + 1)

Set up SCICO projection.

num_angles = 3


rot_X = 90.0 - 16.0
rot_Y = np.linspace(0, 180, num_angles, endpoint=False)
angles = np.stack(np.broadcast_arrays(rot_X, rot_Y), axis=-1)
matrices = XRayTransform3D.matrices_from_euler_angles(
    in_shape, out_shape, "XY", angles, degrees=True
)

Specify geometry using SCICO conventions and project.

num_repeats = 3

timer_scico = Timer()
with ContextTimer(timer_scico, "init"):
    H_scico = XRayTransform3D(in_shape, matrices, out_shape)

with ContextTimer(timer_scico, "first_fwd"):
    y_scico = H_scico @ x
    jax.block_until_ready(y_scico)

with ContextTimer(timer_scico, "avg_fwd"):
    for _ in range(num_repeats):
        y_scico = H_scico @ x
        jax.block_until_ready(y_scico)
timer_scico.td["avg_fwd"] /= num_repeats

with ContextTimer(timer_scico, "first_back"):
    HTy_scico = H_scico.T @ y_scico

with ContextTimer(timer_scico, "avg_back"):
    for _ in range(num_repeats):
        HTy_scico = H_scico.T @ y_scico
        jax.block_until_ready(HTy_scico)
timer_scico.td["avg_back"] /= num_repeats

Convert SCICO geometry to ASTRA and project.

vectors_from_scico = astra.convert_from_scico_geometry(in_shape, matrices, out_shape)

timer_astra = Timer()
with ContextTimer(timer_astra, "init"):
    H_astra_from_scico = astra.XRayTransform3D(
        input_shape=in_shape, det_count=out_shape, vectors=vectors_from_scico
    )

with ContextTimer(timer_astra, "first_fwd"):
    y_astra_from_scico = H_astra_from_scico @ x
    jax.block_until_ready(y_astra_from_scico)

with ContextTimer(timer_astra, "avg_fwd"):
    for _ in range(num_repeats):
        y_astra_from_scico = H_astra_from_scico @ x
        jax.block_until_ready(y_astra_from_scico)
timer_astra.td["avg_fwd"] /= num_repeats

with ContextTimer(timer_astra, "first_back"):
    HTy_astra_from_scico = H_astra_from_scico.T @ y_astra_from_scico

with ContextTimer(timer_astra, "avg_back"):
    for _ in range(num_repeats):
        HTy_astra_from_scico = H_astra_from_scico.T @ y_astra_from_scico
        jax.block_until_ready(HTy_astra_from_scico)
timer_astra.td["avg_back"] /= num_repeats

Specify geometry with ASTRA conventions and project.

angles = np.random.rand(num_angles) * 180  # random projection angles
det_spacing = [1.0, 1.0]
vectors = astra.angle_to_vector(det_spacing, angles)

H_astra = astra.XRayTransform3D(input_shape=in_shape, det_count=out_shape, vectors=vectors)

y_astra = H_astra @ x
HTy_astra = H_astra.T @ y_astra

Convert ASTRA geometry to SCICO and project.

P_from_astra = astra._astra_to_scico_geometry(H_astra.vol_geom, H_astra.proj_geom)
H_scico_from_astra = XRayTransform3D(in_shape, P_from_astra, out_shape)

y_scico_from_astra = H_scico_from_astra @ x
HTy_scico_from_astra = H_scico_from_astra.T @ y_scico_from_astra

Print timing results.

print(f"init         astra    {timer_astra.td['init']:.2e} s")
print(f"init         scico    {timer_scico.td['init']:.2e} s")
print("")
for tstr in ("first", "avg"):
    for dstr in ("fwd", "back"):
        for timer, pstr in zip((timer_astra, timer_scico), ("astra", "scico")):
            print(f"{tstr:5s}  {dstr:4s}  {pstr}    {timer.td[tstr + '_' + dstr]:.2e} s")
        print()

init         astra    1.04e-04 s
init         scico    9.71e-01 s

first  fwd   astra    5.27e-02 s
first  fwd   scico    4.84e-02 s

first  back  astra    4.84e-02 s
first  back  scico    6.53e-01 s

avg    fwd   astra    4.67e-02 s
avg    fwd   scico    4.90e-02 s

avg    back  astra    4.59e-02 s
avg    back  scico    3.31e-02 s

Show projections.

fig, ax = plot.subplots(nrows=3, ncols=2, figsize=(8, 10))
plot.imview(y_scico[0], title="SCICO projections", cbar=None, fig=fig, ax=ax[0, 0])
plot.imview(y_scico[1], cbar=None, fig=fig, ax=ax[1, 0])
plot.imview(y_scico[2], cbar=None, fig=fig, ax=ax[2, 0])
plot.imview(y_astra_from_scico[:, 0], title="ASTRA projections", cbar=None, fig=fig, ax=ax[0, 1])
plot.imview(y_astra_from_scico[:, 1], cbar=None, fig=fig, ax=ax[1, 1])
plot.imview(y_astra_from_scico[:, 2], cbar=None, fig=fig, ax=ax[2, 1])
fig.suptitle("Using SCICO conventions")
fig.tight_layout()
fig.show()

fig, ax = plot.subplots(nrows=3, ncols=2, figsize=(8, 10))
plot.imview(y_scico_from_astra[0], title="SCICO projections", cbar=None, fig=fig, ax=ax[0, 0])
plot.imview(y_scico_from_astra[1], cbar=None, fig=fig, ax=ax[1, 0])
plot.imview(y_scico_from_astra[2], cbar=None, fig=fig, ax=ax[2, 0])
plot.imview(y_astra[:, 0], title="ASTRA projections", cbar=None, fig=fig, ax=ax[0, 1])
plot.imview(y_astra[:, 1], cbar=None, fig=fig, ax=ax[1, 1])
plot.imview(y_astra[:, 2], cbar=None, fig=fig, ax=ax[2, 1])
fig.suptitle("Using ASTRA conventions")
fig.tight_layout()
fig.show()

Show back projections.

fig, ax = plot.subplots(nrows=1, ncols=2, figsize=(8, 5))
plot.imview(HTy_scico[N // 2], title="SCICO back projection", cbar=None, fig=fig, ax=ax[0])
plot.imview(
    HTy_astra_from_scico[N // 2], title="ASTRA back projection", cbar=None, fig=fig, ax=ax[1]
)
fig.suptitle("Using SCICO conventions")
fig.tight_layout()
fig.show()

fig, ax = plot.subplots(nrows=1, ncols=2, figsize=(8, 5))
plot.imview(
    HTy_scico_from_astra[N // 2], title="SCICO back projection", cbar=None, fig=fig, ax=ax[0]
)
plot.imview(HTy_astra[N // 2], title="ASTRA back projection", cbar=None, fig=fig, ax=ax[1])
fig.suptitle("Using ASTRA conventions")
fig.tight_layout()
fig.show()