wiener_deblur

pysaber.wiener_deblur(rad, sod, odd, pix_wid, src_pars, det_pars, reg_par)

Function to reduce blur (deblur) in a radiograph using Wiener filtering.

Parameters

  • rad (numpy.ndarray) – Normalized radiograph to deblur

  • sod (float) – Source to object distance (SOD) for the radiograph rad.

  • odd (float) – Object to detector distance (SDD) for the radiograph rad.

  • 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.

  • reg_par (float) – Regularization parameter for Wiener filter. Noise and ringing artifacts in the deblurred radiograph decreases with increasing values for reg_par and vice versa. But, note that increasing reg_par can also result in excessive blurring due to over-regulization. It is recommended to empirically choose this parameter by increasing or decreasing it by a factor, greater than one (such as 2 or 10), until the desired image quality is achieved.

Returns

Deblurred radiograph using a Wiener filter.

Return type

numpy.ndarray