SNARK93

A programming system for 2-D image reconstruction from projections for the UNIX/Sun environment

Department of Computer Science, The Graduate Center, CUNY

SNARK93 is a programming system designed to help researchers interested in developing and evaluating reconstruction algorithms for image reconstruction from projections. It is the latest in a series of releases of SNARK. One of these, SNARK77, is described in some detail in the book by G.T. Herman, Image Reconstruction from Projections: The Fundamentals of Computerized Tomography, Academic Press, New York, 1980; in fact, all illustrations of two dimensional reconstructions (by a large variety of algorithms) in that book were produced by SNARK77. Additional reconstruction algorithms can be found in SNARK93, such as the linogram method of Edholm, Herman, and Roberts (IEEE Trans. on Med. Imaging, vol. 7, pp. 239-246, 1987), the maximum likelihood EM algorithm of Shepp and Vardi (IEEE Trans. Med. Imaging, vol. 6, pp. 113-122, 1982), and the maximum a posteriori probability algorithm of Herman, De Pierro, Gai (J. Visual Comm. and Image Proc., vol. 3, pp. 316-324, 1992). SNARK93 also provides a methodology for testing for statistically significant task-specific performance differences between algorithms, as illustrated in the papers by Herman and Odhner (IEEE Trans. Med. Imaging, vol. 10, pp. 336-346, 1991) and Herman and Meyer (IEEE Trans. Med. Imaging, vol. 12, pp. 600-609,1992). It also extends the capability of previous SNARK releases (which simulate data collection in X-ray computed tomography) to emission tomography. SNARK93 has been designed to be flexible and transportable, in places at the expense of efficiency. While it may also be used to reconstruct repeatedly from data collected by a particular device, a special purpose program for that device is likely to be much more efficient.

The SNARK93 programming system is designed to:

  1. be capable of generating mathematically described phantoms realistically representing various cross-sections of the human body;
  2. be capable of generating mathematically simulated projection data of such cross-sections reflecting the characteristics (geometrical arrangements of sources and detectors, spectra, noise properties, etc.) of various possible tomographic data-collection devices;
  3. contain many of the published reconstruction algorithms;
  4. contain subroutines to carry out work which appears to be common to many reconstruction algorithms, so as to facilitate the incorporation of additional (user-defined) algorithms;
  5. contain routines for the evaluation of single reconstructions and provide a methodology for testing for statistically significant differences between reconstruction algorithms;
  6. be capable of displaying the reconstructed images and plotting several distance measures between the original object and the reconstructed image.
SNARK93 will be made available to all who request it at the cost of reproduction and mailing of the FORTRAN source code and the manual. The software and the manual may also be received via ftp (in which case we will require a login ID and a password). We charge US$200.00 (checks only; drawn on a U.S. bank) for providing this service. For overseas mailing add another US$50.00 if air mail delivery is required. Please make the check payable to RFCUNY on behalf of CISDD and send it with your order to:

Gabor T. Herman

Department of Computer Science
The Graduate Center
City University of New York
365 Fifth Avenue
New York, NY 10016
U.S.A.

 email:  gherman@gc.cuny.edu

SNARK93 Confidentiality Agreement & Disclaimer

By purchasing the SNARK93 software, the recipient agrees to abide by the following terms:
  1. SNARK93 shall not be redistributed in any way.
  2. SNARK93 is not a patient-care tool and it is not approved by the United States Federal Drug Administration.
  3. While every effort has been made to correct all known bugs, SNARK93 is provided "as is" with no warranty whatsoever. As such, the recipient agrees not to hold the authors responsible for any problems they may encounter with the software.
  4. The recipient agrees to purchase SNARK93 with the explicit knowledge that the authors do not offer technical support.