Tomographic reconstructions using map algorithms - application to the SPIDR mission

Ghosh Roy, D.N. ; Wilton, K. ; Cook, T.A. ; Chakrabarti, S. ; Qi, J. ; Gullberg, G.T.

Lawrence Berkeley National Laboratory

关键词: Spectra;    99 General And Miscellaneous//Mathematics, Computing, And Information Science;    Free Enthalpy;    Algorithms;    Astronomy;   

DOI  :  10.2172/838183
RP-ID  :  LBNL--54934
RP-ID  :  AC03-76SF00098
RP-ID  :  838183

美国|英语

来源: UNT Digital Library

【 摘 要 】

The spectral image of an astronomical scene is reconstructed from noisy tomographic projections using maximum a posteriori (MAP) and filtered backprojection (FBP) algorithms. Both maximum entropy (ME) and Gibbs prior are used in the MAP reconstructions. The scene, which is a uniform background with a localized emissive source superimposed on it, is reconstructed for a broad range of source counts. The algorithms are compared regarding their ability to detect the source in the background. Detectability is defined in terms of a contrast-to-noise ratio (CNR) which is a Monte Carlo ensemble average of spatially averaged CNRs for the individual reconstructions. Overall, MAP was found to yield improved CNR relative to FBP. Moreover, as a function of the total source counts, the CNR varies distinctly different for source and background regions. This may be important in separating a weak source from the background.