Introduction to Image Reduction

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Motivation & background Instrumental Signature Removal Combining multiple images Photometric calibration Why don’t we remove effect of PSF by deconvolving? from GREAT08, Bridle et al Deconvolution works well only in the high-S/N limit. (Same is true of many classical image-processing techniques.) Lensers extract lensing-specific corrections from the PSF, or forward-model the whole process.
Motivation & background Instrumental Signature Removal Combining multiple images Photometric calibration Combining multiple images: overview Conceptually, simply “coadd” multiple images of the same field to obtain a higher S/N “stacked image.” 20x → This is a form of lossy data compression with (usually) high compression and low loss. There may be better ways to analyze your dataset (eg comeasurement, model fitting), but you usually want a stack at least for reference purposes.
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Introduction to Image Reduction

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