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Updated LSF function #191

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merged 3 commits into from
Dec 22, 2021
Merged

Updated LSF function #191

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1ee3f13
updated lsf fun
Lucrezia-Cester Dec 22, 2021
6dd2ac3
updated spat_res tests to work with new lsf fun
Lucrezia-Cester Dec 22, 2021
223d760
removed superflous print statements
Lucrezia-Cester Dec 22, 2021
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51 changes: 4 additions & 47 deletions hazenlib/spatial_resolution.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,52 +22,9 @@

import hazenlib


def maivis_deriv(x, a, h=1, n=1, axis=-1):
"""
Performs differentiation the same way as done with MAIVIS to find the line spread function (LSF). This function has been re-implemented from IDL code written by Ioannis.

;differentiate the ESF the same way as done with MAIVIS to find the line spread function (LSF)
max_deriv=FIX(n_elements(ESF)/4)

lsf=FLTARR(4*max_deriv)

for lsf_element=0, 4*max_deriv-4 do begin

aa=ESF(lsf_element)+ESF(lsf_element+1)
bb=ESF(lsf_element+2)+ESF(lsf_element+3)
lsf(lsf_element)=(bb-aa)/2

end

;pad the last 3 elements of the lsf
for lsf_element=4*max_deriv-3, 4*max_deriv-1 do begin
lsf(lsf_element)=lsf(4*max_deriv-4)
end

Parameters
----------
a : array_like
Input array
n : int, optional
The number of times values are differenced.
axis : int, optional
The axis along which the difference is taken, default is the last axis.
Returns
-------
diff : ndarray
The `n` order differences. The shape of the output is the same as `a`
except along `axis` where the dimension is smaller by `n`.
See Also
--------
idl_deriv
numpy.diff

"""
max_deriv = len(a) // 4
b = [(a[i + 2] + a[i + 3] - a[i] - a[i + 1]) / 2 for i in range(4 * max_deriv - 3)]
# pad last 3 elements of b
b.extend([b[-1]] * 3)
def deri(a):
# This function calculated the LSF by taking the derivative of the ESF. Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3643984/
b = np.gradient(a)
return b


Expand Down Expand Up @@ -440,7 +397,7 @@ def calculate_mtf_for_edge(dicom, edge, report_path=False):
angle, intercept = get_edge_angle_and_intercept(x_edge, y_edge)
x, y = get_edge_profile_coords(angle, intercept, spacing)
u, esf = get_esf(edge_arr, y)
lsf = maivis_deriv(u, esf)
lsf = deri(esf)
lsf = np.array(lsf)
n=lsf.size
mtf = abs(np.fft.fft(lsf))
Expand Down
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