The current practice involves interpretation of these resultant images to give any useful information on the size and location of defects. Some of these imaging techniques use Fourier transforms in processing the raw data, and in this process final images are produced by mathematical inversion of the processed data.

We know that the Fourier transform of any image gives the frequency aspects of that image. This information regarding the frequency content of an image can sometimes give vital clues leading to the details of the structure of the specimen. This "Fourier Vision" is illustrated, in the paper, by a set of tomographic images taken by the X-ray CT scanner designed and developed at the Fraunhofer-Institute for NDT [1]. REFERENCES

1. J. Zhou, P. Munshi, M. Maisl and H. Reiter, "An investigation of higher order tomographic filters using Fourier transform of reconstructed images", Nuclear Instruments and Methods in Physics Research, B88 (1994) pp. 485-489
2. G. T. Herman, Image reconstruction from projections: The fundamentals of computerized tomography, John Wiley (1980), New York
3. P. Munshi, "Error analysis of tomographic filters I: Theory", NDT & E International, 25 (1992) pp. 191-194
4. P. Munshi, R. K. S. Rathore, K. S. Ram and M. S. Kalra, "Error analysis of tomographic filters II: Results", NDT & E International 26 (1993) pp. 235-240