Class lsst::meas::base::PeakLikelihoodFluxControl

class PeakLikelihoodFluxControl

C++ control object for peak likelihood instrument flux.

Peak likelihood flux requires an image that has been filtered by convolving with its own PSF (or an approximate model). It is equivalent to a PSF instrument flux (e.g. as computed by PsfFluxAlgorithm) computed on a non-preconvolved image.

The PSF must be provided in the exposure, as it is used to compute a weighting factor.

Flux and error are computed as follows:

• instFlux = sum(unfiltered image * PSF) / sum(PSF^2) = value of peak of filtered source / sum(PSF^2)

• err = sqrt(sum(unfiltered variance * PSF^2) / sum(PSF^2)^2) = sqrt(value of filtered variance at peak / sum(PSF^2)^2)

• The pixels in the image are samples of a band-limited function, and by using a sinc interpolation (via a warping kernel) we can evaluate this function at any point. We use this technique to compute the peak of the function, which is assumed to be at the centroid of the filtered source.