Improved Convergence for CCD Gain Calibration Using Simultaneous-Overrelaxation Techniques
Abstract
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 (sqrt(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.
- Publication:
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The Astronomical Journal
- Pub Date:
- August 2003
- DOI:
- 10.1086/376846
- Bibcode:
- 2003AJ....126.1112T
- Keywords:
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- Techniques: Image Processing