lsst.ip.diffim.subtractImages Namespace Reference

Classes
class	AlardLuptonSubtractConfig
class	AlardLuptonSubtractConnections
class	AlardLuptonSubtractTask
class	SubtractImageOutputConnections
class	SubtractInputConnections

Functions
def	checkTemplateIsSufficient (templateExposure, logger, requiredTemplateFraction=0.)

Function Documentation

checkTemplateIsSufficient()

def lsst.ip.diffim.subtractImages.checkTemplateIsSufficient	(		templateExposure,
			logger,
			requiredTemplateFraction = 0.
	)

Raise NoWorkFound if template coverage < requiredTemplateFraction

Parameters
----------
templateExposure : `lsst.afw.image.ExposureF`
    The template exposure to check
logger : `lsst.log.Log`
    Logger for printing output.
requiredTemplateFraction : `float`, optional
    Fraction of pixels of the science image required to have coverage
    in the template.

Raises
------
lsst.pipe.base.NoWorkFound
    Raised if fraction of good pixels, defined as not having NO_DATA
    set, is less then the configured requiredTemplateFraction

Definition at line 492 of file subtractImages.py.

def checkTemplateIsSufficient(templateExposure, logger, requiredTemplateFraction=0.):
    """Raise NoWorkFound if template coverage < requiredTemplateFraction
 
    Parameters
    ----------
    templateExposure : `lsst.afw.image.ExposureF`
        The template exposure to check
    logger : `lsst.log.Log`
        Logger for printing output.
    requiredTemplateFraction : `float`, optional
        Fraction of pixels of the science image required to have coverage
        in the template.
 
    Raises
    ------
    lsst.pipe.base.NoWorkFound
        Raised if fraction of good pixels, defined as not having NO_DATA
        set, is less then the configured requiredTemplateFraction
    """
    # Count the number of pixels with the NO_DATA mask bit set
    # counting NaN pixels is insufficient because pixels without data are often intepolated over)
    pixNoData = np.count_nonzero(templateExposure.mask.array
                                 & templateExposure.mask.getPlaneBitMask('NO_DATA'))
    pixGood = templateExposure.getBBox().getArea() - pixNoData
    logger.info("template has %d good pixels (%.1f%%)", pixGood,
                100*pixGood/templateExposure.getBBox().getArea())
 
    if pixGood/templateExposure.getBBox().getArea() < requiredTemplateFraction:
        message = ("Insufficient Template Coverage. (%.1f%% < %.1f%%) Not attempting subtraction. "
                   "To force subtraction, set config requiredTemplateFraction=0." % (
                       100*pixGood/templateExposure.getBBox().getArea(),
                       100*requiredTemplateFraction))
        raise lsst.pipe.base.NoWorkFound(message)