apply_blur_psfs

pysaber.apply_blur_psfs(rad, sod, odd, pix_wid, src_pars, det_pars, padded_widths=[0, 0], pad_type='constant', pad_constant=0)

Function to blur the input radiograph with point spread functions (PSF) of X-ray source and detector blurs.

This function blurs the input radiograph with X-ray source blur and detector blur with the specified point spread function (PSF) parameters. This function is useful to observe the effect of source and detector blurs on a simulated radiograph.

Parameters

  • rad (numpy.ndarray) – Radiograph of type numpy.ndarray that is normalized using the bright-field (also called flat-field) and dark-field images.

  • sod (float) – Source to object distance (SOD) of radiograph.

  • odd (float) – Object to detector distance (ODD) of radiograph.

  • pix_wid (float) – Effective width of each detector pixel. Note that this is the effective pixel size given by dividing the physical width of each detector pixel by the zoom factor of the optical lens.

  • src_pars (dict) – Dictionary containing the estimated parameters of X-ray source PSF. It consists of several key-value pairs. The value for key source_FWHM_x_axis is the full width half maximum (FWHM) of the source PSF along the x-axis (i.e., second numpy.ndarray dimension). The value for key source_FWHM_y_axis is the FWHM of source PSF along the y-axis (i.e., first numpy.ndarray dimension). All FWHMs are for the source PSF in the plane of the X-ray source (and not the plane of the detector). The value for key cutoff_FWHM_multiplier decides the non-zero spatial extent of the source PSF. The PSF is clipped to zero beginning at a distance, as measured from the PSF’s origin, equal to the maximum of src_pars['cutoff_FWHM_multiplier'] times src_pars['source_FWHM_x_axis']/2 and src_pars['cutoff_FWHM_multiplier'] times src_pars['source_FWHM_y_axis']/2.

  • det_pars (dict) – Dictionary containing the estimated parameters of detector PSF. It consists of several key-value pairs. The value for key detector_FWHM_1 is the FWHM of the first density function in the mixture density model for detector blur. The first density function is the most dominant part of detector blur. The value for key detector_FWHM_2 is the FWHM of the second density function in the mixture density model. This density function has the largest FWHM and models the long running tails of the detector blur’s PSF. The value for key detector_weight_1 is between 0 and 1 and is a measure of the amount of contribution of the first density function to the detector blur. The values for keys cutoff_FWHM_1_multiplier and cutoff_FWHM_2_multiplier decide the non-zero spatial extent of the detector PSF. The PSF is clipped to zero beginning at a distance, as measured from the PSF’s origin, equal to the maximum of det_pars['cutoff_FWHM_1_multiplier'] times det_pars['detector_FWHM_1']/2 and det_pars['cutoff_FWHM_2_multiplier'] times det_pars['detector_FWHM_2']/2.

  • padded_widths (list) – List of two integers that specifies the amount of padding already applied to input radiograph. The first integer specifies the padding applied along the first dimension of radiograph. The second integer specifies the padding applied along the second dimension of radiograph. Assumes padded_widths[k]/2 amount of padding is applied at both the left and right extremities of dimension k, where k is 0 or 1.

  • pad_type (str) – Type of additional padding that must be used if amount of padding specified in padded_widths is insufficient. Supported values are edge and constant.

  • pad_constant (float) – If pad_type is constant, specify the constant value that must be padded.

Returns

Radiograph that is blurred using X-ray source and detector blurs.

Return type

numpy.ndarray