Bayesian approach to the thermally generated charge elimination
Jan Švihlík · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2007
It is generally known that every astronomical image, which was acquired by CCD sensor, has to be corrected by dark frame. The Dark frame maps the thermally generated charge of the CCD. May become that the dark frame image is not available and it is impossible to correct the astronomical images directly. It is good to note that uncorrected images are not suitable for subsequent investigation. There are simple nonlinear filtering methods, e.g. median filtering, but the obtained results are not so satisfactory. During the recent year the algorithms for the thermally generated charge elimination were proposed. All these algorithms use the Discrete Wavelet Transform (DWT). The DWT transforms image into different frequency bands. Wavelet coefficients histogram should be modeled by generalized Laplacian probability density function (PDF). The Laplacian parameters were estimated by moment method using derived equation system. Furthermore, the images, where the thermally generated charge was suppressed, were estimated using Bayesian estimators. This algorithm will be in the future improved, but now to the promising eliminating algorithm should be involved.