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LSST Data Management Base Package
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utils.py
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1# This file is part of afw.
2#
3# Developed for the LSST Data Management System.
4# This product includes software developed by the LSST Project
5# (https://www.lsst.org).
6# See the COPYRIGHT file at the top-level directory of this distribution
7# for details of code ownership.
8#
9# This program is free software: you can redistribute it and/or modify
10# it under the terms of the GNU General Public License as published by
11# the Free Software Foundation, either version 3 of the License, or
12# (at your option) any later version.
13#
14# This program is distributed in the hope that it will be useful,
15# but WITHOUT ANY WARRANTY; without even the implied warranty of
16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17# GNU General Public License for more details.
18#
19# You should have received a copy of the GNU General Public License
20# along with this program. If not, see <https://www.gnu.org/licenses/>.
21
22__all__ = ["clipImage", "projectImage", "getProjectionIndices"]
23
24import lsst.afw.detection as afwDetect
25from ._maskedImage import MaskedImage, makeMaskedImage
26from ._image import Mask
27
28
29def clipImage(im, minClip, maxClip):
30 """Clip an image to lie between minClip and maxclip (None to ignore)"""
31 if isinstance(im, MaskedImage):
32 mi = im
33 else:
34 mi = makeMaskedImage(im, Mask(im.getDimensions()))
35
36 if minClip is not None:
37 ds = afwDetect.FootprintSet(
38 mi, afwDetect.Threshold(-minClip, afwDetect.Threshold.VALUE, False))
39 afwDetect.setImageFromFootprintList(
40 mi.getImage(), ds.getFootprints(), minClip)
41
42 if maxClip is not None:
43 ds = afwDetect.FootprintSet(mi, afwDetect.Threshold(maxClip))
44 afwDetect.setImageFromFootprintList(
45 mi.getImage(), ds.getFootprints(), maxClip)
46
47
48def getProjectionIndices(imageBBox, targetBBox):
49 """Get the indices to project an image
50
51 Given an image and target bounding box,
52 calculate the indices needed to appropriately
53 slice the input image and target image to
54 project the image to the target.
55
56 Parameters
57 ----------
58 imageBBox: Box2I
59 Bounding box of the input image
60 targetBBox: Box2I
61 Bounding box of the target image
62
63 Returns
64 -------
65 targetSlices: tuple
66 Slices of the target image in the form (by, bx), (iy, ix).
67 imageIndices: tuple
68 Slices of the input image in the form (by, bx), (iy, ix).
69 """
70 def getMin(dXmin):
71 """Get minimum indices"""
72 if dXmin < 0:
73 bxStart = -dXmin
74 ixStart = 0
75 else:
76 bxStart = 0
77 ixStart = dXmin
78 return bxStart, ixStart
79
80 def getMax(dXmax):
81 """Get maximum indices"""
82 if dXmax < 0:
83 bxEnd = None
84 ixEnd = dXmax
85 elif dXmax != 0:
86 bxEnd = -dXmax
87 ixEnd = None
88 else:
89 bxEnd = ixEnd = None
90 return bxEnd, ixEnd
91
92 dXmin = targetBBox.getMinX() - imageBBox.getMinX()
93 dXmax = targetBBox.getMaxX() - imageBBox.getMaxX()
94 dYmin = targetBBox.getMinY() - imageBBox.getMinY()
95 dYmax = targetBBox.getMaxY() - imageBBox.getMaxY()
96
97 bxStart, ixStart = getMin(dXmin)
98 byStart, iyStart = getMin(dYmin)
99 bxEnd, ixEnd = getMax(dXmax)
100 byEnd, iyEnd = getMax(dYmax)
101
102 bx = slice(bxStart, bxEnd)
103 by = slice(byStart, byEnd)
104 ix = slice(ixStart, ixEnd)
105 iy = slice(iyStart, iyEnd)
106 return (by, bx), (iy, ix)
107
108
109def projectImage(image, bbox, fill=0):
110 """Project an image into a bounding box
111
112 Return a new image whose pixels are equal to those of
113 `image` within `bbox`, and equal to `fill` outside.
114
115 Parameters
116 ----------
117 image: `afw.Image` or `afw.MaskedImage`
118 The image to project
119 bbox: `Box2I`
120 The bounding box to project onto.
121 fill: number
122 The value to fill the region of the new
123 image outside the bounding box of the original.
124
125 Returns
126 -------
127 newImage: `afw.Image` or `afw.MaskedImage`
128 The new image with the input image projected
129 into its bounding box.
130 """
131 if image.getBBox() == bbox:
132 return image
133 (by, bx), (iy, ix) = getProjectionIndices(image.getBBox(), bbox)
134
135 if isinstance(image, MaskedImage):
136 newImage = type(image.image)(bbox)
137 newImage.array[by, bx] = image.image.array[iy, ix]
138 newMask = type(image.mask)(bbox)
139 newMask.array[by, bx] = image.mask.array[iy, ix]
140 newVariance = type(image.image)(bbox)
141 newVariance.array[by, bx] = image.variance.array[iy, ix]
142 newImage = MaskedImage(image=newImage, mask=newMask, variance=newVariance, dtype=newImage.array.dtype)
143 else:
144 newImage = type(image)(bbox)
145 if fill != 0:
146 newImage.set(fill)
147 newImage.array[by, bx] = image.array[iy, ix]
148 return newImage
projectImage(image, bbox, fill=0)
Definition utils.py:109
clipImage(im, minClip, maxClip)
Definition utils.py:29
getProjectionIndices(imageBBox, targetBBox)
Definition utils.py:48