Improved convergence for CCD gain calibration using simultaneous-overrelaxation techniques

R. M. Toussaint, J. W. Harvey, Doug Toussaint

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Simple modifications to the analysis used in the Kuhn, Lin, & Loranz flat-field CCD calibration method yield significant improvements in both speed and accuracy. In this method, multiple exposures are taken of a time-independent signal at different spatial positions. The flat field is then expressed in the form of a Jacobi relaxation solution to Poisson's equation. By applying the technique of simultaneous overrelaxation, we have improved the convergence rate to require approximately the square root of the number of iterations (√r) needed by the Jacobi method. For large arrays, where r is correspondingly large, this improvement is significant. Furthermore, we have improved the accuracy by extending the method to account for fractional pixel shifts.

Original languageEnglish (US)
Pages (from-to)1112-1118
Number of pages7
JournalAstronomical Journal
Issue number2 1772
StatePublished - Aug 2003


  • Techniques: image processing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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