def test_slice_from_3d():
# Resample a 3d image, returning a zslice, yslice and xslice
#
# This example creates a coordmap that coincides with
# a given z, y, or x slice of an image, and checks that
# resampling agrees with the data in the given slice.
shape = (100,90,80)
g = AffineTransform.from_params('ijk',
'xyz',
np.diag([0.5,0.5,0.5,1]))
img = Image(np.ones(shape), g)
img.get_data()[50:55,40:55,30:33] = 3
I = np.identity(4)
zsl = slices.zslice(26,
((0,49.5), 100),
((0,44.5), 90),
img.reference)
ir = resample(img, zsl, I, (100, 90))
assert_array_almost_equal(ir.get_data(), img[:,:,53].get_data())
ysl = slices.yslice(22,
((0,49.5), 100),
((0,39.5), 80),
img.reference)
ir = resample(img, ysl, I, (100, 80))
assert_array_almost_equal(ir.get_data(), img[:,45,:].get_data())
xsl = slices.xslice(15.5,
((0,44.5), 90),
((0,39.5), 80),
img.reference)
ir = resample(img, xsl, I, (90, 80))
assert_array_almost_equal(ir.get_data(), img[32,:,:].get_data())
def test_resample_outvalue():
# Test resampling with different modes, constant values, datatypes, orders
def func(xyz):
return xyz + np.asarray([1, 0, 0])
coordmap = vox2mni(np.eye(4))
arr = np.arange(3 * 3 * 3).reshape(3, 3, 3)
aff = np.eye(4)
aff[0, 3] = 1. # x translation
for mapping, dt, order in product(
[aff, func],
[np.int8, np.intp, np.int32, np.int64, np.float32, np.float64],
[0, 1, 3]):
img = Image(arr.astype(dt), coordmap)
# Test constant value of 0
img2 = resample(img,
coordmap,
mapping,
img.shape,
order=order,
mode='constant',
cval=0.)
exp_arr = np.zeros(arr.shape)
exp_arr[:-1, :, :] = arr[1:, :, :]
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test constant value of 1
img2 = resample(img,
coordmap,
mapping,
img.shape,
order=order,
mode='constant',
cval=1.)
exp_arr[-1, :, :] = 1
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test nearest neighbor
img2 = resample(img,
coordmap,
mapping,
img.shape,
order=order,
mode='nearest')
exp_arr[-1, :, :] = arr[-1, :, :]
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test img2img
target_coordmap = vox2mni(aff)
target = Image(arr, target_coordmap)
img2 = resample_img2img(img, target, 3, 'nearest')
assert_array_almost_equal(img2.get_data(), exp_arr)
img2 = resample_img2img(img, target, 3, 'constant', cval=1.)
exp_arr[-1, :, :] = 1
assert_array_almost_equal(img2.get_data(), exp_arr)
def test_nonaffine():
# resamples an image along a curve through the image.
#
# FIXME: use the reference.evaluate.Grid to perform this nicer
# FIXME: Remove pylab references
def curve(x): # function accept N by 1, returns N by 2
return np.vstack([5 * np.sin(x.T), 5 * np.cos(x.T)]).T + [52, 47]
for names in (("xy", "ij", "t", "u"), ("ij", "xy", "t", "s")):
in_names, out_names, tin_names, tout_names = names
g = AffineTransform.from_params(in_names, out_names, np.identity(3))
img = Image(np.ones((100, 90)), g)
img[50:55, 40:55] = 3.0
tcoordmap = AffineTransform.from_start_step(tin_names, tout_names, [0], [np.pi * 1.8 / 100])
ir = resample(img, tcoordmap, curve, (100,))
if gui_review:
import pylab
pylab.figure(num=3)
pylab.imshow(img, interpolation="nearest")
d = curve(np.linspace(0, 1.8 * np.pi, 100))
pylab.plot(d[0], d[1])
pylab.gca().set_ylim([0, 99])
pylab.gca().set_xlim([0, 89])
pylab.figure(num=4)
pylab.plot(np.asarray(ir))
def resamp(nipy_img, onto_aff, onto_shape, order=3, cval=-1, w2wmap=None, debug=0):
"""
utility function to resample an image
input:
nipy image
onto affine
onto shape
order : scipy resample interpolation order
cval: value outside when resampling to bigger box
"""
arraycoo = 'ijklmnopq'[:len(onto_shape)]
spacecoo = 'xyztrsuvw'[:len(onto_shape)]
if debug: print('\narraycoo: ', arraycoo,
'\nspacecoo: ', spacecoo, '\nonto_aff\n', onto_aff)
dmaker = CoordSysMaker(arraycoo, 'generic-array')
rmaker = CoordSysMaker(spacecoo, 'generic-scanner')
cm_maker = cmap.CoordMapMaker(dmaker, rmaker)
cmap_out = cm_maker.make_affine(onto_aff)
if debug: print('cmap_out:\n',cmap_out)
if w2wmap == None: w2wmap = np.eye(onto_aff.shape[0])
if debug: print('w2wmap:\n',w2wmap)
return resample(nipy_img, cmap_out, w2wmap, onto_shape, order=order, cval=cval)
def test_nonaffine():
# resamples an image along a curve through the image.
#
# FIXME: use the reference.evaluate.Grid to perform this nicer
# FIXME: Remove pylab references
def curve(x): # function accept N by 1, returns N by 2
return (np.vstack([5 * np.sin(x.T), 5 * np.cos(x.T)]).T + [52, 47])
for names in (('xy', 'ij', 't', 'u'), ('ij', 'xy', 't', 's')):
in_names, out_names, tin_names, tout_names = names
g = AffineTransform.from_params(in_names, out_names, np.identity(3))
img = Image(np.ones((100, 90)), g)
img.get_data()[50:55, 40:55] = 3.
tcoordmap = AffineTransform.from_start_step(tin_names, tout_names, [0],
[np.pi * 1.8 / 100])
ir = resample(img, tcoordmap, curve, (100, ))
if gui_review:
import pylab
pylab.figure(num=3)
pylab.imshow(img, interpolation='nearest')
d = curve(np.linspace(0, 1.8 * np.pi, 100))
pylab.plot(d[0], d[1])
pylab.gca().set_ylim([0, 99])
pylab.gca().set_xlim([0, 89])
pylab.figure(num=4)
pylab.plot(ir.get_data())
def resample_image(source_file, target_file, outdir, w2wmap=None, order=3,
cval=0, verbose=0):
""" Resample the source image to match the target image using Nipy.
Parameters
----------
source_file: str (mandatory)
the image to resample.
target_file: str (mandatory)
the reference image.
outdir: str (mandatory)
the folder where the resampled image will be saved.
w2wmap: array (4, 4) or callable
physical to physical transformation.
verbose: int (optional, default 0)
the verbosity level.
Returns
-------
resampled_file: str
the resampled image.
"""
# Get target image information
target_image = nipy.load_image(target_file)
onto_shape = target_image.shape[:3]
onto_aff = xyz_affine(target_image.affine, xyz=[0, 1, 2], verbose=verbose)
# Define index and physical coordinate systems
arraycoo = "ijklmnopq"[:len(onto_shape)]
spacecoo = "xyztrsuvw"[:len(onto_shape)]
if verbose > 0:
print("\narraycoo: ", arraycoo, "\nspacecoo: ", spacecoo,
"\nonto_aff\n", onto_aff)
dmaker = CoordSysMaker(arraycoo, 'generic-array')
rmaker = CoordSysMaker(spacecoo, 'generic-scanner')
cm_maker = cmap.CoordMapMaker(dmaker, rmaker)
cmap_out = cm_maker.make_affine(onto_aff)
if verbose > 0:
print("cmap_out:\n", cmap_out)
# Define the default physical to physical transformation
if w2wmap is None:
w2wmap = np.eye(onto_aff.shape[0])
if verbose > 0:
print("w2wmap:\n", w2wmap)
# Resample
source_image = nipy.load_image(source_file)
resampled_image = resample(
source_image, cmap_out, w2wmap, onto_shape, order=order, cval=cval)
# Save the resampled image
resampled_file = os.path.join(
outdir, "resampled_{0}".format(os.path.basename(source_file)))
nipy.save_image(resampled_image, resampled_file)
return resampled_file
def test_resample2d3():
# Same as test_resample2d, only a different way of specifying
# the transform: here it is an (A,b) pair
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5,0.5,1]))
i = Image(np.ones((100,90)), g)
i.get_data()[50:55,40:55] = 3.
a = np.identity(3)
a[:2,-1] = 4.
ir = resample(i, i.coordmap, a, (100,90))
assert_array_almost_equal(ir.get_data()[42:47,32:47], 3.)
def test_resample2d2():
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5,0.5,1]))
i = Image(np.ones((100,90)), g)
i.get_data()[50:55,40:55] = 3.
a = np.identity(3)
a[:2,-1] = 4.
A = np.identity(2)
b = np.ones(2)*4
ir = resample(i, i.coordmap, (A, b), (100,90))
assert_array_almost_equal(ir.get_data()[42:47,32:47], 3.)
def test_resample2d2():
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i.get_data()[50:55, 40:55] = 3.
a = np.identity(3)
a[:2, -1] = 4.
A = np.identity(2)
b = np.ones(2) * 4
ir = resample(i, i.coordmap, (A, b), (100, 90))
assert_array_almost_equal(ir.get_data()[42:47, 32:47], 3.)
def test_resample2d3():
# Same as test_resample2d, only a different way of specifying
# the transform: here it is an (A,b) pair
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i.get_data()[50:55, 40:55] = 3.
a = np.identity(3)
a[:2, -1] = 4.
ir = resample(i, i.coordmap, a, (100, 90))
assert_array_almost_equal(ir.get_data()[42:47, 32:47], 3.)
def test_resample2d3():
# Same as test_resample2d, only a different way of specifying
# the transform: here it is an (A,b) pair
g = AffineTransform.from_params("ij", "xy", np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i[50:55, 40:55] = 3.0
a = np.identity(3)
a[:2, -1] = 4.0
ir = resample(i, i.coordmap, a, (100, 90))
yield assert_array_almost_equal, ir[42:47, 32:47], 3.0
def test_resample2d2():
g = AffineTransform.from_params("ij", "xy", np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i[50:55, 40:55] = 3.0
a = np.identity(3)
a[:2, -1] = 4.0
A = np.identity(2)
b = np.ones(2) * 4
ir = resample(i, i.coordmap, (A, b), (100, 90))
yield assert_array_almost_equal, ir[42:47, 32:47], 3.0
def test_rotate2d():
# Rotate an image in 2d on a square grid, should result in transposed image
g = AffineTransform.from_params('ij', 'xy', np.diag([0.7, 0.5, 1]))
g2 = AffineTransform.from_params('ij', 'xy', np.diag([0.5, 0.7, 1]))
i = Image(np.ones((100, 100)), g)
# This sets the image data by writing into the array
i.get_data()[50:55, 40:55] = 3.
a = np.array([[0, 1, 0], [1, 0, 0], [0, 0, 1]], np.float)
ir = resample(i, g2, a, (100, 100))
assert_array_almost_equal(ir.get_data().T, i.get_data())
def test_slice_from_3d():
# Resample a 3d image, returning a zslice, yslice and xslice
#
# This example creates a coordmap that coincides with
# a given z, y, or x slice of an image, and checks that
# resampling agrees with the data in the given slice.
shape = (100, 90, 80)
g = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5, 0.5, 0.5, 1]))
img = Image(np.ones(shape), g)
img.get_data()[50:55, 40:55, 30:33] = 3
I = np.identity(4)
zsl = slices.zslice(26, ((0, 49.5), 100), ((0, 44.5), 90), img.reference)
ir = resample(img, zsl, I, (100, 90))
assert_array_almost_equal(ir.get_data(), img[:, :, 53].get_data())
ysl = slices.yslice(22, ((0, 49.5), 100), ((0, 39.5), 80), img.reference)
ir = resample(img, ysl, I, (100, 80))
assert_array_almost_equal(ir.get_data(), img[:, 45, :].get_data())
xsl = slices.xslice(15.5, ((0, 44.5), 90), ((0, 39.5), 80), img.reference)
ir = resample(img, xsl, I, (90, 80))
assert_array_almost_equal(ir.get_data(), img[32, :, :].get_data())
def test_slice_from_3d():
# Resample a 3d image, returning a zslice, yslice and xslice
#
# This example creates a coordmap that coincides with
# the 10th slice of an image, and checks that
# resampling agrees with the data in the 10th slice.
shape = (100, 90, 80)
g = AffineTransform.from_params("ijk", "xyz", np.diag([0.5, 0.5, 0.5, 1]))
i = Image(np.ones(shape), g)
i[50:55, 40:55, 30:33] = 3
a = np.identity(4)
zsl = slices.zslice(26, ((0, 44.5), 90), ((0, 39.5), 80), i.reference)
ir = resample(i, zsl, a, (90, 80))
yield assert_true(np.allclose(np.asarray(ir), np.asarray(i[53])))
ysl = slices.yslice(22, (0, 49.5), (0, 39.5), i.reference, (100, 80))
ir = resample(i, ysl.coordmap, a, ysl.shape)
yield assert_true(np.allclose(np.asarray(ir), np.asarray(i[:, 45])))
xsl = slices.xslice(15.5, (0, 49.5), (0, 44.5), i.reference, (100, 90))
ir = resample(i, xsl.coordmap, a, xsl.shape)
yield assert_true(np.allclose(np.asarray(ir), np.asarray(i[:, :, 32])))
def test_rotate3d():
# Rotate / transpose a 3d image on a non-square grid
g = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5, 0.6, 0.7, 1]))
g2 = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5, 0.7, 0.6, 1]))
shape = (100, 90, 80)
i = Image(np.ones(shape), g)
i.get_data()[50:55, 40:55, 30:33] = 3.
a = np.array([[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 1.]])
ir = resample(i, g2, a, (100, 80, 90))
assert_array_almost_equal(np.transpose(ir.get_data(), (0, 2, 1)),
i.get_data())
def test_rotate2d():
# Rotate an image in 2d on a square grid, should result in transposed image
g = AffineTransform.from_params('ij', 'xy', np.diag([0.7,0.5,1]))
g2 = AffineTransform.from_params('ij', 'xy', np.diag([0.5,0.7,1]))
i = Image(np.ones((100,100)), g)
# This sets the image data by writing into the array
i.get_data()[50:55,40:55] = 3.
a = np.array([[0,1,0],
[1,0,0],
[0,0,1]], np.float)
ir = resample(i, g2, a, (100, 100))
assert_array_almost_equal(ir.get_data().T, i.get_data())
def test_resample_outvalue():
# Test resampling with different modes, constant values, datatypes, orders
def func(xyz):
return xyz + np.asarray([1,0,0])
coordmap = vox2mni(np.eye(4))
arr = np.arange(3 * 3 * 3).reshape(3, 3, 3)
aff = np.eye(4)
aff[0, 3] = 1. # x translation
for mapping, dt, order in product(
[aff, func],
[np.int8, np.intp, np.int32, np.int64, np.float32, np.float64],
[0, 1, 3]):
img = Image(arr.astype(dt), coordmap)
# Test constant value of 0
img2 = resample(img, coordmap, mapping, img.shape,
order=order, mode='constant', cval=0.)
exp_arr = np.zeros(arr.shape)
exp_arr[:-1, :, :] = arr[1:, :, :]
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test constant value of 1
img2 = resample(img, coordmap, mapping, img.shape,
order=order, mode='constant', cval=1.)
exp_arr[-1, :, :] = 1
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test nearest neighbor
img2 = resample(img, coordmap, mapping, img.shape,
order=order, mode='nearest')
exp_arr[-1, :, :] = arr[-1, :, :]
assert_array_almost_equal(img2.get_data(), exp_arr)
# Test img2img
target_coordmap = vox2mni(aff)
target = Image(arr, target_coordmap)
img2 = resample_img2img(img, target, 3, 'nearest')
assert_array_almost_equal(img2.get_data(), exp_arr)
img2 = resample_img2img(img, target, 3, 'constant', cval=1.)
exp_arr[-1, :, :] = 1
assert_array_almost_equal(img2.get_data(), exp_arr)
def test_2d_from_3d():
# Resample a 3d image on a 2d affine grid
# This example creates a coordmap that coincides with
# the 10th slice of an image, and checks that
# resampling agrees with the data in the 10th slice.
shape = (100, 90, 80)
g = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5, 0.5, 0.5, 1]))
i = Image(np.ones(shape), g)
i.get_data()[50:55, 40:55, 30:33] = 3.
a = np.identity(4)
g2 = ArrayCoordMap.from_shape(g, shape)[10]
ir = resample(i, g2.coordmap, a, g2.shape)
assert_array_almost_equal(ir.get_data(), i[10].get_data())
def test_2d_from_3d():
# Resample a 3d image on a 2d affine grid
# This example creates a coordmap that coincides with
# the 10th slice of an image, and checks that
# resampling agrees with the data in the 10th slice.
shape = (100, 90, 80)
g = AffineTransform.from_params("ijk", "xyz", np.diag([0.5, 0.5, 0.5, 1]))
i = Image(np.ones(shape), g)
i[50:55, 40:55, 30:33] = 3.0
a = np.identity(4)
g2 = ArrayCoordMap.from_shape(g, shape)[10]
ir = resample(i, g2.coordmap, a, g2.shape)
yield assert_array_almost_equal, np.asarray(ir), np.asarray(i[10])
def test_rotate3d():
# Rotate / transpose a 3d image on a non-square grid
g = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5,0.6,0.7,1]))
g2 = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5,0.7,0.6,1]))
shape = (100,90,80)
i = Image(np.ones(shape), g)
i.get_data()[50:55,40:55,30:33] = 3.
a = np.array([[1,0,0,0],
[0,0,1,0],
[0,1,0,0],
[0,0,0,1.]])
ir = resample(i, g2, a, (100,80,90))
assert_array_almost_equal(np.transpose(ir.get_data(), (0,2,1)),
i.get_data())
def test_resample2d1():
# Tests the same as test_resample2d, only using a callable instead of
# an AffineTransform instance
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5,0.5,1]))
i = Image(np.ones((100,90)), g)
i.get_data()[50:55,40:55] = 3.
a = np.identity(3)
a[:2,-1] = 4.
A = np.identity(2)
b = np.ones(2)*4
def mapper(x):
return np.dot(x, A.T) + b
ir = resample(i, i.coordmap, mapper, (100,90))
assert_array_almost_equal(ir.get_data()[42:47,32:47], 3.)
def test_rotate3d():
# Rotate / transpose a 3d image on a non-square grid
g = AffineTransform.from_params("ijk", "xyz", np.diag([0.5, 0.6, 0.7, 1]))
g2 = AffineTransform.from_params("ijk", "xyz", np.diag([0.5, 0.7, 0.6, 1]))
shape = (100, 90, 80)
i = Image(np.ones(shape), g)
i[50:55, 40:55, 30:33] = 3.0
a = np.array([[1, 0, 0, 0], [0, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 1.0]])
ir = resample(i, g2, a, (100, 80, 90))
yield assert_array_almost_equal, np.transpose(np.asarray(ir), (0, 2, 1)), i
def test_rotate2d2():
# Rotate an image in 2d on a non-square grid,
# should result in transposed image
g = AffineTransform.from_params("ij", "xy", np.diag([0.7, 0.5, 1]))
g2 = AffineTransform.from_params("ij", "xy", np.diag([0.5, 0.7, 1]))
i = Image(np.ones((100, 80)), g)
i[50:55, 40:55] = 3.0
a = np.array([[0, 1, 0], [1, 0, 0], [0, 0, 1]], np.float)
ir = resample(i, g2, a, (80, 100))
yield assert_array_almost_equal, np.asarray(ir).T, i
def test_resample2d():
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i.get_data()[50:55, 40:55] = 3.
# This mapping describes a mapping from the "target" physical
# coordinates to the "image" physical coordinates. The 3x3 matrix
# below indicates that the "target" physical coordinates are related
# to the "image" physical coordinates by a shift of -4 in each
# coordinate. Or, to find the "image" physical coordinates, given
# the "target" physical coordinates, we add 4 to each "target
# coordinate". The resulting resampled image should show the
# overall image shifted -8,-8 voxels towards the origin
a = np.identity(3)
a[:2, -1] = 4.
ir = resample(i, i.coordmap, a, (100, 90))
assert_array_almost_equal(ir.get_data()[42:47, 32:47], 3.)
def test_resample2d1():
# Tests the same as test_resample2d, only using a callable instead of
# an AffineTransform instance
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5, 0.5, 1]))
i = Image(np.ones((100, 90)), g)
i.get_data()[50:55, 40:55] = 3.
a = np.identity(3)
a[:2, -1] = 4.
A = np.identity(2)
b = np.ones(2) * 4
def mapper(x):
return np.dot(x, A.T) + b
ir = resample(i, i.coordmap, mapper, (100, 90))
assert_array_almost_equal(ir.get_data()[42:47, 32:47], 3.)
def test_resample2d():
g = AffineTransform.from_params('ij', 'xy', np.diag([0.5,0.5,1]))
i = Image(np.ones((100,90)), g)
i.get_data()[50:55,40:55] = 3.
# This mapping describes a mapping from the "target" physical
# coordinates to the "image" physical coordinates. The 3x3 matrix
# below indicates that the "target" physical coordinates are related
# to the "image" physical coordinates by a shift of -4 in each
# coordinate. Or, to find the "image" physical coordinates, given
# the "target" physical coordinates, we add 4 to each "target
# coordinate". The resulting resampled image should show the
# overall image shifted -8,-8 voxels towards the origin
a = np.identity(3)
a[:2,-1] = 4.
ir = resample(i, i.coordmap, a, (100,90))
assert_array_almost_equal(ir.get_data()[42:47,32:47], 3.)
def test_resample3d():
g = AffineTransform.from_params('ijk', 'xyz', np.diag([0.5, 0.5, 0.5, 1]))
shape = (100, 90, 80)
i = Image(np.ones(shape), g)
i.get_data()[50:55, 40:55, 30:33] = 3.
# This mapping describes a mapping from the "target" physical
# coordinates to the "image" physical coordinates. The 4x4 matrix
# below indicates that the "target" physical coordinates are related
# to the "image" physical coordinates by a shift of -4 in each
# coordinate. Or, to find the "image" physical coordinates, given
# the "target" physical coordinates, we add 4 to each "target
# coordinate". The resulting resampled image should show the
# overall image shifted [-6,-8,-10] voxels towards the origin
a = np.identity(4)
a[:3, -1] = [3, 4, 5]
ir = resample(i, i.coordmap, a, (100, 90, 80))
assert_array_almost_equal(ir.get_data()[44:49, 32:47, 20:23], 3.)
def test_resample3d():
g = AffineTransform.from_params("ijk", "xyz", np.diag([0.5, 0.5, 0.5, 1]))
shape = (100, 90, 80)
i = Image(np.ones(shape), g)
i[50:55, 40:55, 30:33] = 3.0
# This mapping describes a mapping from the "target" physical
# coordinates to the "image" physical coordinates. The 4x4 matrix
# below indicates that the "target" physical coordinates are related
# to the "image" physical coordinates by a shift of -4 in each
# coordinate. Or, to find the "image" physical coordinates, given
# the "target" physical coordinates, we add 4 to each "target
# coordinate". The resulting resampled image should show the
# overall image shifted [-6,-8,-10] voxels towards the origin
a = np.identity(4)
a[:3, -1] = [3, 4, 5]
ir = resample(i, i.coordmap, a, (100, 90, 80))
yield assert_array_almost_equal, ir[44:49, 32:47, 20:23], 3.0
def test_rotate2d3():
# Another way to rotate/transpose the image, similar to
# test_rotate2d2 and test_rotate2d, except the world of the
# output coordmap is the same as the world of the
# original image. That is, the data is transposed on disk, but the
# output coordinates are still 'x,'y' order, not 'y', 'x' order as
# above
# this functionality may or may not be used a lot. if data is to
# be transposed but one wanted to keep the NIFTI order of output
# coords this would do the trick
g = AffineTransform.from_params('xy', 'ij', np.diag([0.5, 0.7, 1]))
i = Image(np.ones((100, 80)), g)
# This sets the image data by writing into the array
i.get_data()[50:55, 40:55] = 3.
a = np.identity(3)
g2 = AffineTransform.from_params(
'xy', 'ij', np.array([[0, 0.5, 0], [0.7, 0, 0], [0, 0, 1]]))
ir = resample(i, g2, a, (80, 100))
assert_array_almost_equal(ir.get_data().T, i.get_data())
def test_rotate2d3():
# Another way to rotate/transpose the image, similar to
# test_rotate2d2 and test_rotate2d, except the world of the
# output coordmap is the same as the world of the
# original image. That is, the data is transposed on disk, but the
# output coordinates are still 'x,'y' order, not 'y', 'x' order as
# above
# this functionality may or may not be used a lot. if data is to
# be transposed but one wanted to keep the NIFTI order of output
# coords this would do the trick
g = AffineTransform.from_params('xy', 'ij', np.diag([0.5,0.7,1]))
i = Image(np.ones((100,80)), g)
# This sets the image data by writing into the array
i.get_data()[50:55,40:55] = 3.
a = np.identity(3)
g2 = AffineTransform.from_params('xy', 'ij', np.array([[0,0.5,0],
[0.7,0,0],
[0,0,1]]))
ir = resample(i, g2, a, (80,100))
assert_array_almost_equal(ir.get_data().T, i.get_data())
def test_rotate2d3():
# Another way to rotate/transpose the image, similar to
# test_rotate2d2 and test_rotate2d except the world of the
# output coordmap are the same as the world of the
# original image. That is, the data is transposed on disk, but the
# output coordinates are still 'x,'y' order, not 'y', 'x' order as
# above
# this functionality may or may not be used a lot. if data is to
# be transposed but one wanted to keep the NIFTI order of output
# coords this would do the trick
g = AffineTransform.from_params("xy", "ij", np.diag([0.5, 0.7, 1]))
i = Image(np.ones((100, 80)), g)
i[50:55, 40:55] = 3.0
a = np.identity(3)
g2 = AffineTransform.from_params("xy", "ij", np.array([[0, 0.5, 0], [0.7, 0, 0], [0, 0, 1]]))
ir = resample(i, g2, a, (80, 100))
v2v = compose(g.inverse(), g2)
yield assert_array_almost_equal, np.asarray(ir).T, i
def test_subsample():
# This is how you would subsample with nipy.algorithms.resample
# On the first axis, we'll take every 2nd,
# on the second axis every 3rd, and on the 3rd every 4th
im, xyz_im, ras = generate_im()
subsample_matrix = np.array([[2,0,0,0],
[0,3,0,0],
[0,0,4,0],
[0,0,0,1]])
subsampled_shape = np.array(xyz_im)[::2,::3,::4].shape
subsample_coordmap = AffineTransform(xyz_im.xyz_transform.function_domain,
xyz_im.xyz_transform.function_domain,
subsample_matrix)
target_coordmap = compose(xyz_im.xyz_transform,
subsample_coordmap)
# The images have the same output coordinates
world_to_world_coordmap = AffineTransform(xyz_im.xyz_transform.function_range,
xyz_im.xyz_transform.function_range,
np.identity(4))
im_subsampled = resample(xyz_im, target_coordmap,
world_to_world_coordmap,
shape=subsampled_shape)
xyz_im_subsampled = xyz_image.XYZImage(np.array(im_subsampled),
im_subsampled.affine,
im_subsampled.coordmap.function_domain.coord_names)
yield assert_almost_equal, np.array(xyz_im_subsampled), np.array(xyz_im)[::2,::3,::4]
# We can now do subsampling with these methods.
xyz_im_subsampled2 = xyz_im.resampled_to_affine(target_coordmap,
shape=subsampled_shape)
yield assert_almost_equal, np.array(xyz_im_subsampled2), np.array(xyz_im_subsampled)
yield assert_true, xyz_im_subsampled2 == xyz_im_subsampled
def _set_coef_block( self,
coords = None,
mask = MASK_FULL,
upsample = True ):
"""
Gets a coefficient block corresponding to a set of model parameters.
"""
if coords is None:
coords = [self.x_coord, self.y_coord, self.z_coord, self.t_coord]
coefs = self._get_coefs( self.params )
ims = unmask( coefs, mask )
im = ims[ coords[3] ] / np.fabs( ims[ coords[3] ] ).max()
im = Image( im, self.anatim.coordmap )
if upsample == True:
print 'resampling'
if self.affine_resample is None:
h = R.HistogramRegistration( im, self.anathi )
self.affine_resample = h.optimize( 'affine' ).as_affine()
resampled_im = resample( im,
self.anathi.coordmap,
self.affine_resample,
self.anathi.shape,
order = 1 )
# reim = resample( im, self.anathi.coordmap, np.identity(4), self.anathi.shape, order=1 )
print 'done'
# im = np.ma.masked_array( np.asarray(reim), np.less( np.fabs(reim), 0.05 ) )
im = np.asarray( resampled_im )
self.im = im
def resampled_to_affine(self, affine_transform,
world_to_world=None,
interpolation_order=3,
shape=None):
""" Resample the image to be an affine image.
Parameters
----------
affine_transform : XYZTransform
Affine of the new grid.
world_to_world: 4x4 ndarray, optional
A matrix representing a mapping from the target's "world"
to self's "world". Defaults to np.identity(4)
interpolation_order : int, optional
Order of the spline interplation. If 0, nearest-neighbour
interpolation is performed.
shape: tuple
Shape of the resulting image. Defaults to self.shape.
Returns
-------
resampled_image : XYZImage
New nipy image with the data resampled in the given
affine.
Notes
-----
The coordinate system of the output image is the world of
affine_transform. Therefore, if world_to_world=np.identity(4), the
coordinate system is not changed: the returned image points to the
same world space.
"""
shape = shape or self.shape
shape = shape[:3]
if world_to_world is None:
world_to_world = np.identity(4)
world_to_world_transform = AffineTransform(affine_transform.function_range,
self.reference, world_to_world)
if self.ndim == 3:
# we import ``resample`` here because an earlier import causes
# an import error, during build, because of the statistics
# import of compile modules. This is not a good fix, but it
# will do for now.
from nipy.algorithms.resample import resample
im = resample(self, affine_transform, world_to_world_transform,
shape, order=interpolation_order)
return XYZImage(np.array(im), affine_transform.affine,
affine_transform.function_domain.coord_names,
metadata=self.metadata)
# XXX this below wasn't included in the original XYZImage
# proposal and it would fail for an XYZImage with ndim == 4. I
# don't know if it should be included as a special case in the
# XYZImage, but then we should at least raise an exception
# saying that these resample_* methods only work for XYZImage's
# with ndim==3.
#
# This is part of the reason nipy.core.image.Image does not have
# resample_* methods...
elif self.ndim == 4:
result = np.empty(shape + (self.shape[3],))
data = self.get_data()
for i in range(self.shape[3]):
tmp_affine_im = XYZImage(data[...,i], self.affine,
self.axes.coord_names[:-1],
metadata=self.metadata)
tmp_im = tmp_affine_im.resampled_to_affine(affine_transform,
world_to_world,
interpolation_order,
shape)
result[...,i] = np.array(tmp_im)
return XYZImage(result, affine_transform.affine,
self.axes.coord_names,
metadata=self.metadata)
else:
raise ValueError('resampling only defined for 3d and 4d XYZImage')
# downsample to make smaller output image
downsamp = 1/3
epi_scale = np.diag([downsamp, downsamp, downsamp, 1])
# template voxels to epi box image voxels
vox2epi_vox = epi_scale.dot(rot.dot(epi_trans))
# epi image voxels to mm
epi_vox2mm = t2_img.affine.dot(npl.inv(vox2epi_vox))
# downsampled image shape
epi_vox_shape = np.array([data.shape[0], epi_x_len, epi_y_len]) * downsamp
# Make sure dimensions are odd by rounding up or down
# This makes the voxel center an integer index, which is convenient
epi_vox_shape = [np.floor(d) if np.floor(d) % 2 else np.ceil(d)
for d in epi_vox_shape]
# resample, preserving affine
epi_cmap = nca.vox2mni(epi_vox2mm)
epi = rsm.resample(t2_img, epi_cmap, np.eye(4), epi_vox_shape)
epi_data = epi.get_data()
# Do the same kind of thing for the anatomical scan
anat_vox_sizes = [2.75, 2.75, 2.75]
anat_scale = npl.inv(np.diag(anat_vox_sizes + [1]))
anat_trans = np.eye(4)
anat_trans[:3, 3] = -np.array([0, anat_box[0, 0], anat_box[0, 1]])
vox2anat_vox = anat_scale.dot(anat_trans)
anat_vox2mm = t1_img.affine.dot(npl.inv(vox2anat_vox))
anat_vox_shape = np.round(np.divide(
[data.shape[0], anat_x_len, anat_y_len], anat_vox_sizes))
anat_cmap = nca.vox2mni(anat_vox2mm)
anat = rsm.resample(t1_img, anat_cmap, np.eye(4), anat_vox_shape)
anat_data = anat.get_data()
save_plot()
def resampled_to_affine(self, affine_transform, world_to_world=None,
interpolation_order=3,
shape=None):
""" Resample the image to be an affine image.
Parameters
----------
affine_transform : AffineTransform
Affine of the new grid.
XXX In the original proposal, it said something about "if only 3x3 it is assumed
to be a rotation", but this wouldn't work the way the code was written becuase
it was written as if affine was the affine of an AffineImage. So, if you input
a "rotation matrix" that is assuming you have voxels of size 1....
This rotation can now be expressed with the world_to_world argument.
world_to_world: 4x4 ndarray, optional
A matrix representing a mapping from the target's (affine_transform) "world"
to self's "world". Defaults to np.identity(4)
interpolation_order : int, optional
Order of the spline interplation. If 0, nearest-neighbour
interpolation is performed.
shape: tuple
Shape of the resulting image. Defaults to self.shape.
Returns
-------
resampled_image : nipy AffineImage
New nipy image with the data resampled in the given
affine.
Notes
-----
The coordinate system of the resampled_image is the world
of affine_transform. Therefore, if world_to_world=np.identity(4),
the coordinate system is not changed: the
returned image points to the same world space.
"""
shape = shape or self.shape
shape = shape[:3]
if world_to_world is None:
world_to_world = np.identity(4)
world_to_world_transform = AffineTransform(affine_transform.function_range,
self.spatial_coordmap.function_range,
world_to_world)
if self.ndim == 3:
im = resample(self, affine_transform, world_to_world_transform,
shape, order=interpolation_order)
return AffineImage(np.array(im), affine_transform.affine,
affine_transform.function_domain.name)
# XXX this below wasn't included in the original AffineImage proposal
# and it would fail for an AffineImage with ndim == 4.
# I don't know if it should be included as a special case in the AffineImage,
# but then we should at least raise an exception saying that these resample_* methods
# only work for AffineImage's with ndim==3.
#
# This is part of the reason nipy.core.image.Image does not have
# resample_* methods...
elif self.ndim == 4:
result = np.empty(shape + (self.shape[3],))
data = self.get_data()
for i in range(self.shape[3]):
tmp_affine_im = AffineImage(data[...,i], self.affine,
self.axis_names[:-1])
tmp_im = tmp_affine_im.resampled_to_affine(affine_transform,
world_to_world,
interpolation_order,
shape)
result[...,i] = np.array(tmp_im)
return AffineImage(result, affine_transform.affine,
affine_transform.function_domain.name)
else:
raise ValueError('resampling only defined for 3d and 4d AffineImage')
def resample_image(source_file, target_file, output_directory,
w2wmap_file=None, erode_path_nb=0, order=3,
cval=0.0):
""" Resample the source image to match the target image using Nipy.
Parameters
----------
source_file: str (mandatory)
the image to resample.
target_file: str (mandatory)
the reference image.
outdir: str (mandatory)
the folder where the resampled image will be saved.
w2wmap: array (4, 4) or callable
physical to physical transformation.
erode_path_nb: Int (optional, default 1)
the number of path of the erosion. Performed before resampling.
verbose: int (optional, default 0)
the verbosity level.
Returns
-------
resampled_file: str
the resampled image.
CAPSUL header
-------------
<process capsul_xml="2.0">
<input name="source_file" type="file" doc="the image to resample."/>
<input name="target_file" type="file" doc="the reference image."/>
<input name="output_directory" type="directory" doc="the folder where the resampled image will be saved."/>
<input name="w2wmap_file" type="file" doc="physical to physical transformation file."/>
<input name="erode_path_nb" type="int" doc="the number of path in erosion of the mask"/>
<input name="order" type="int" doc="interpolation mode, 0 = nearest neighbour"/>
<input name="cval" type="float" doc=""/>
<return name="resampled_file" type="file" doc="the resampled image."/>
</process>
"""
verbose = 0
# get world to world transformation
# SPM version
w2wmap = scipy.io.loadmat(w2wmap_file)["Affine"]
# fsl version
# w2wmap = np.fromfile(w2wmap_file, sep=" ")
# w2wmap = w2wmap.reshape(4, 4)
w2wmap = np.linalg.inv(w2wmap)
# Get target image information
target_image = nipy.load_image(target_file)
onto_shape = target_image.shape[:3]
onto_aff = xyz_affine(target_image.affine, xyz=[0, 1, 2], verbose=verbose)
# Define index and physical coordinate systems
arraycoo = "ijklmnopq"[:len(onto_shape)]
spacecoo = "xyztrsuvw"[:len(onto_shape)]
if verbose > 0:
print("\narraycoo: ", arraycoo, "\nspacecoo: ", spacecoo,
"\nonto_aff\n", onto_aff)
dmaker = CoordSysMaker(arraycoo, 'generic-array')
rmaker = CoordSysMaker(spacecoo, 'generic-scanner')
cm_maker = cmap.CoordMapMaker(dmaker, rmaker)
cmap_out = cm_maker.make_affine(onto_aff)
if verbose > 0:
print("cmap_out:\n", cmap_out)
# Define the default physical to physical transformation
if w2wmap is None:
w2wmap = np.eye(onto_aff.shape[0])
if verbose > 0:
print("w2wmap:\n", w2wmap)
# erode anatomic mask if requestd
if erode_path_nb > 0:
structuring_element = np.array([[[0, 0, 0],
[0, 1, 0],
[0, 0, 0]],
[[0, 1, 0],
[1, 1, 1],
[0, 1, 0]],
[[0, 0, 0],
[0, 1, 0],
[0, 0, 0]]])
# get anatomic mask
source_image = nibabel.load(source_file)
source_data = source_image.get_data()
eroded_image = binary_erosion(
source_data,
iterations=erode_path_nb,
structure=structuring_element).astype(source_data.dtype)
# save
_temp = nibabel.Nifti1Image(eroded_image, source_image.get_affine())
source_file = os.path.join(output_directory,
'eroded_anat_mask.nii.gz')
nibabel.save(_temp, source_file)
# Get eroded anatomic mask
source_image = nipy.load_image(source_file)
# resample
resampled_image = resample(
source_image, cmap_out, w2wmap, onto_shape, order=order, cval=cval)
# save
resampled_file = os.path.join(
output_directory,
"resampled_{0}".format(os.path.basename(source_file)))
nipy.save_image(resampled_image, resampled_file)
# if not os.path.isfile(resampled_file):
# raise ValueError("NO RESAMPLED FILE")
return resampled_file
