lsst.afw.image.utils Namespace Reference

Functions
	clipImage (im, minClip, maxClip)
	getProjectionIndices (imageBBox, targetBBox)
	projectImage (image, bbox, fill=0)

Function Documentation

clipImage()

lsst.afw.image.utils.clipImage	(		im,
			minClip,
			maxClip )

Clip an image to lie between minClip and maxclip (None to ignore)

Definition at line 29 of file utils.py.

def clipImage(im, minClip, maxClip):
    """Clip an image to lie between minClip and maxclip (None to ignore)"""
    if isinstance(im, MaskedImage):
        mi = im
    else:
        mi = makeMaskedImage(im, Mask(im.getDimensions()))
 
    if minClip is not None:
        ds = afwDetect.FootprintSet(
            mi, afwDetect.Threshold(-minClip, afwDetect.Threshold.VALUE, False))
        afwDetect.setImageFromFootprintList(
            mi.getImage(), ds.getFootprints(), minClip)
 
    if maxClip is not None:
        ds = afwDetect.FootprintSet(mi, afwDetect.Threshold(maxClip))
        afwDetect.setImageFromFootprintList(
            mi.getImage(), ds.getFootprints(), maxClip)
 
 

getProjectionIndices()

lsst.afw.image.utils.getProjectionIndices	(		imageBBox,
			targetBBox )

Get the indices to project an image

Given an image and target bounding box,
calculate the indices needed to appropriately
slice the input image and target image to
project the image to the target.

Parameters
----------
imageBBox: Box2I
    Bounding box of the input image
targetBBox: Box2I
    Bounding box of the target image

Returns
-------
targetSlices: tuple
    Slices of the target image in the form (by, bx), (iy, ix).
imageIndices: tuple
    Slices of the input image in the form (by, bx), (iy, ix).

Definition at line 48 of file utils.py.

def getProjectionIndices(imageBBox, targetBBox):
    """Get the indices to project an image
 
    Given an image and target bounding box,
    calculate the indices needed to appropriately
    slice the input image and target image to
    project the image to the target.
 
    Parameters
    ----------
    imageBBox: Box2I
        Bounding box of the input image
    targetBBox: Box2I
        Bounding box of the target image
 
    Returns
    -------
    targetSlices: tuple
        Slices of the target image in the form (by, bx), (iy, ix).
    imageIndices: tuple
        Slices of the input image in the form (by, bx), (iy, ix).
    """
    def getMin(dXmin):
        """Get minimum indices"""
        if dXmin < 0:
            bxStart = -dXmin
            ixStart = 0
        else:
            bxStart = 0
            ixStart = dXmin
        return bxStart, ixStart
 
    def getMax(dXmax):
        """Get maximum indices"""
        if dXmax < 0:
            bxEnd = None
            ixEnd = dXmax
        elif dXmax != 0:
            bxEnd = -dXmax
            ixEnd = None
        else:
            bxEnd = ixEnd = None
        return bxEnd, ixEnd
 
    dXmin = targetBBox.getMinX() - imageBBox.getMinX()
    dXmax = targetBBox.getMaxX() - imageBBox.getMaxX()
    dYmin = targetBBox.getMinY() - imageBBox.getMinY()
    dYmax = targetBBox.getMaxY() - imageBBox.getMaxY()
 
    bxStart, ixStart = getMin(dXmin)
    byStart, iyStart = getMin(dYmin)
    bxEnd, ixEnd = getMax(dXmax)
    byEnd, iyEnd = getMax(dYmax)
 
    bx = slice(bxStart, bxEnd)
    by = slice(byStart, byEnd)
    ix = slice(ixStart, ixEnd)
    iy = slice(iyStart, iyEnd)
    return (by, bx), (iy, ix)
 
 

projectImage()

lsst.afw.image.utils.projectImage	(		image,
			bbox,
			fill = 0 )

Project an image into a bounding box

Return a new image whose pixels are equal to those of
`image` within `bbox`, and equal to `fill` outside.

Parameters
----------
image: `afw.Image` or `afw.MaskedImage`
    The image to project
bbox: `Box2I`
    The bounding box to project onto.
fill: number
    The value to fill the region of the new
    image outside the bounding box of the original.

Returns
-------
newImage: `afw.Image` or `afw.MaskedImage`
    The new image with the input image projected
    into its bounding box.

Definition at line 109 of file utils.py.

def projectImage(image, bbox, fill=0):
    """Project an image into a bounding box
 
    Return a new image whose pixels are equal to those of
    `image` within `bbox`, and equal to `fill` outside.
 
    Parameters
    ----------
    image: `afw.Image` or `afw.MaskedImage`
        The image to project
    bbox: `Box2I`
        The bounding box to project onto.
    fill: number
        The value to fill the region of the new
        image outside the bounding box of the original.
 
    Returns
    -------
    newImage: `afw.Image` or `afw.MaskedImage`
        The new image with the input image projected
        into its bounding box.
    """
    if image.getBBox() == bbox:
        return image
    (by, bx), (iy, ix) = getProjectionIndices(image.getBBox(), bbox)
 
    if isinstance(image, MaskedImage):
        newImage = type(image.image)(bbox)
        newImage.array[by, bx] = image.image.array[iy, ix]
        newMask = type(image.mask)(bbox)
        newMask.array[by, bx] = image.mask.array[iy, ix]
        newVariance = type(image.image)(bbox)
        newVariance.array[by, bx] = image.variance.array[iy, ix]
        newImage = MaskedImage(image=newImage, mask=newMask, variance=newVariance, dtype=newImage.array.dtype)
    else:
        newImage = type(image)(bbox)
        if fill != 0:
            newImage.set(fill)
        newImage.array[by, bx] = image.array[iy, ix]
    return newImage