Visualize Blur PSF

• For further analysis and visualization, we can also compute the point spread functions (PSF) of source blur and detector blur. The PSF of source blur is computed using the function pysaber.get_source_psf() and PSF of detector blur is computed using pysaber.get_detector_psf().

• The function pysaber.get_source_psf() is useful to compute PSF either in the plane of the X-ray source or the plane of the detector. Since source blur PSF on the detector plane is a function of the object’s source to object distance (SOD) and object to detector distance (ODD), SOD and ODD must be specified when computing source PSF in the plane of the detector. To compute source blur PSF in the source plane, it is sufficient to use the default values for SOD and ODD in pysaber.get_source_psf().

• The detector blur PSF obtained using pysaber.get_detector_psf() models blur due to the scintillator and detector panel. Hence, it is independent of SOD and ODD.

• Example python scripts that demonstrate visualization of source and detector PSFs are shown below.

Plot X-ray source blur PSF

import numpy as np #For mathematics on vectors
import matplotlib.pyplot as plt #For plotting and showing images
from pysaber import get_source_psf #To compute PSF of source blur 

pix_wid = 0.675 #Width of each pixel in micrometers
#Parameters of X-ray source blur
src_params = {'source_FWHM_x_axis':2.69,
                'source_FWHM_y_axis':3.01, 
                'norm_power':1.0,
                'cutoff_FWHM_multiplier':10}

#Get point spread function (PSF) of source blur in the plane of the X-ray source.
#Do not supply SOD and SDD if you need PSF in the source plane.
source_psf = get_source_psf(pix_wid,src_params)

#Display the source blur PSF on the source plane as an image
sz = source_psf.shape
x = np.arange(-(sz[1]//2),(sz[1]//2)+1,1)*pix_wid
y = np.arange(-(sz[0]//2),(sz[0]//2)+1,1)*pix_wid
plt.pcolormesh(x,y,source_psf,cmap='gray')
plt.xlabel('micrometers')
plt.ylabel('micrometers')
plt.title('X-ray source PSF at source plane')
plt.colorbar()
plt.show()

#To get source blur PSF on the detector plane, supply SOD and ODD = SDD - SOD to the function get_source_psf
sod = 25000 #in micrometers
sdd = 71000 #in micrometers
source_psf = get_source_psf(pix_wid,src_params,sod,sdd-sod)

#help(get_source_psf)
#Uncomment the above line to get help on using the function get_source_psf

#Display the source blur PSF on the detector plane as an image
sz = source_psf.shape
x = np.arange(-(sz[1]//2),(sz[1]//2)+1,1)*pix_wid
y = np.arange(-(sz[0]//2),(sz[0]//2)+1,1)*pix_wid
plt.pcolormesh(x,y,source_psf,cmap='gray')
plt.xlabel('micrometers')
plt.ylabel('micrometers')
plt.title('X-ray source PSF at detector plane')
plt.colorbar()
plt.show()

Plot X-ray detector blur PSF

import numpy as np #For mathematics on vectors
import matplotlib.pyplot as plt #For displaying images
from matplotlib.colors import LogNorm #To display image values in logarithm scale 
from pysaber import get_detector_psf #To compute PSF of detector blur

pix_wid = 0.675 #Width of each pixel in micrometers
#Parameters of detector blur
det_params = {'detector_FWHM_1':1.85, 
                'detector_FWHM_2':126.5, 
                'detector_weight_1':0.916, 
                'norm_power':1.0, 
                'cutoff_FWHM_1_multiplier':10, 
                'cutoff_FWHM_2_multiplier':10}

#Get point spread function (PSF) of detector blur as a 2D numpy array.
detector_psf = get_detector_psf(pix_wid,det_params)

#help(get_detector_psf)
#Uncomment the above line to get help in using the function get_detector_psf

#Display the PSF of detector blur
sz = detector_psf.shape
x = np.arange(-(sz[1]//2),(sz[1]//2)+1,1)*pix_wid
y = np.arange(-(sz[0]//2),(sz[0]//2)+1,1)*pix_wid
plt.pcolormesh(x,y,detector_psf,cmap='gray',norm=LogNorm())
plt.xlabel('micrometers')
plt.ylabel('micrometers')
plt.title('Detector PSF')
plt.colorbar()
plt.show()