lsst.synpipe.FakeSourceLib Namespace Reference

Classes
class	SkyMapIdContainer

Functions
def	cropFakeImage (fakeImage, expBBox)
def	addNoise (galImage, detector, rand_gen=None)

Function Documentation

addNoise()

def lsst.synpipe.FakeSourceLib.addNoise	(		galImage,
			detector,
			rand_gen = None
	)

adds noise to the the image and returns a variance plane
INPUT: image to add noise to
       detector where the image will be located, this sets the gain
NOTE: this assumes float type images and will break if given doubles
RETURN: a MaskedImageF with the image with additional noise and the
        variance plane
giving the variance due to the object

Definition at line 63 of file FakeSourceLib.py.

def addNoise(galImage, detector, rand_gen=None):
    """
    adds noise to the the image and returns a variance plane
    INPUT: image to add noise to
           detector where the image will be located, this sets the gain
    NOTE: this assumes float type images and will break if given doubles
    RETURN: a MaskedImageF with the image with additional noise and the
            variance plane
    giving the variance due to the object
    """
    # TODO: this is gaussian noise right now, probably good enough
    varImage = galImage.Factory(galImage, True)
    if rand_gen is None:
        rand_gen = np.random
    scale = np.sqrt(np.abs(varImage.getArray())) + 1e-12
    noiseArray = rand_gen.normal(loc=0.0,
                                 scale=scale,
                                 size=(galImage.getHeight(),
                                       galImage.getWidth()))
    noiseImage = lsst.afw.image.ImageF(noiseArray.astype(np.float32))
    galImage += noiseImage

    return lsst.afw.image.MaskedImageF(galImage, None, varImage)

cropFakeImage()

def lsst.synpipe.FakeSourceLib.cropFakeImage	(		fakeImage,
			expBBox
	)

Crops the Fake image to fit inside the exposure BBox
Note that the bboxes need to have the correct offsets applied
Args:
    fakeImage: fake image object
    expBBox:   bounding box for CCD exposure (integer type, BBoxI)
               and with offsets applied

Returns:
    New cropped fake image

Definition at line 41 of file FakeSourceLib.py.

def cropFakeImage(fakeImage, expBBox):
    """
    Crops the Fake image to fit inside the exposure BBox
    Note that the bboxes need to have the correct offsets applied
    Args:
        fakeImage: fake image object
        expBBox:   bounding box for CCD exposure (integer type, BBoxI)
                   and with offsets applied

    Returns:
        New cropped fake image
    """
    fakeBBox = fakeImage.getBBox(lsst.afw.image.PARENT)

    if not expBBox.contains(fakeBBox):
        newBBox = fakeImage.getBBox(lsst.afw.image.PARENT)
        newBBox.clip(expBBox)
        fakeImage = fakeImage.Factory(fakeImage, newBBox,
                                      lsst.afw.image.PARENT)
        # TODO: finish this up

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