lsst.afw.image.exposure._multiband Namespace Reference

Classes
class	IncompleteDataError
class	MultibandExposure

Functions
def	computePsfImage (psfModels, position, bands, useKernelImage=True)

Function Documentation

computePsfImage()

def lsst.afw.image.exposure._multiband.computePsfImage	(		psfModels,
			position,
			bands,
			useKernelImage = True
	)

Get a multiband PSF image

The PSF Kernel Image is computed for each band
and combined into a (filter, y, x) array.

Parameters
----------
psfList : `list` of `lsst.afw.detection.Psf`
    The list of PSFs in each band.
position : `Point2D` or `tuple`
    Coordinates to evaluate the PSF.
bands: `list` or `str`
        List of names for each band
Returns
-------
psfs: `np.ndarray`
    The multiband PSF image.

Definition at line 41 of file _multiband.py.

def computePsfImage(psfModels, position, bands, useKernelImage=True):
    """Get a multiband PSF image
 
    The PSF Kernel Image is computed for each band
    and combined into a (filter, y, x) array.
 
    Parameters
    ----------
    psfList : `list` of `lsst.afw.detection.Psf`
        The list of PSFs in each band.
    position : `Point2D` or `tuple`
        Coordinates to evaluate the PSF.
    bands: `list` or `str`
            List of names for each band
    Returns
    -------
    psfs: `np.ndarray`
        The multiband PSF image.
    """
    psfs = []
    # Make the coordinates into a Point2D (if necessary)
    if not isinstance(position, Point2D):
        position = Point2D(position[0], position[1])
 
    for bidx, psfModel in enumerate(psfModels):
        try:
            if useKernelImage:
                psf = psfModel.computeKernelImage(position)
            else:
                psf = psfModel.computeImage(position)
            psfs.append(psf)
        except InvalidParameterError:
            # This band failed to compute the PSF due to incomplete data
            # at that location. This is unlikely to be a problem for Rubin,
            # however the edges of some HSC COSMOS fields contain incomplete
            # data in some bands, so we track this error to distinguish it
            # from unknown errors.
            msg = "Failed to compute PSF at {} in band {}"
            raise IncompleteDataError(msg.format(position, bands[bidx])) from None
 
    left = np.min([psf.getBBox().getMinX() for psf in psfs])
    bottom = np.min([psf.getBBox().getMinY() for psf in psfs])
    right = np.max([psf.getBBox().getMaxX() for psf in psfs])
    top = np.max([psf.getBBox().getMaxY() for psf in psfs])
    bbox = Box2I(Point2I(left, bottom), Point2I(right, top))
    psfs = np.array([projectImage(psf, bbox).array for psf in psfs])
    return psfs