Neutron CT enhancement by iterative de-blurring of neutron transmission images

It is well known that neutron radiography lags behind in terms of image spatial resolution compared to X-ray radiography. The reason for this is a combined effect of the beam line geometry, limited detector spatial resolution, scattering… etc. Although a lot of effort has been spent in the last 30 years to improve the resolution of classical digital images, the improvement of radiographic data is hardly ever done. In this paper, we explain why this is the case and come up with an approach to sharpen radiographs. An iterative, accelerated, damped algorithm has been developed to reduce blur artefacts in images obtained from neutron radiography facilities. In this technique, estimates of the radiographic data are convoluted with the detector response function and compared with the original blurred image. Successive iterated estimates of the un-blurred image are obtained by minimizing the square of the difference in pixel count between the original and blurred predicted image. This kind of Lucy-Richardson approach can be used effectively when the point-spread function PSF (blurring operator) is known, but little or no information is available for the noise. Additional optical system (e.g. camera) characteristics can be used as input parameters to improve the quality of the image restoration.