def getBlur(self, fwhm=None, gradient=False):
        blurToReturn = None
        if fwhm == -1:
            blurToReturn = self.basevol
        else:
            if not fwhm:
                fwhm = self.lastblur
                if gradient:
                    fwhm = self.lastgradient
            if gradient:
                # these might not exist, so we need to try this
                try:
                    blurToReturn = self.gradients[fwhm]
                except:
                    print("Error: the gradient file with fwhm ", fwhm, " does not exist for file ", self.basevol)
                    print("Unexpected error: ", sys.exc_info())
                    raise
            else:
                try:
                    blurToReturn = self.blurs[fwhm]
                except:
                    print("Error: the blur file with fwhm ", fwhm, " does not exist for file ", self.basevol)
                    print("Unexpected error: ", sys.exc_info())
                    raise
        return(blurToReturn)
returns file with specified blurring kernel
dataset/ETHPy150Open Mouse-Imaging-Centre/pydpiper/atoms_and_modules/registration_file_handling.py/RegistrationGroupedFiles.getBlur