piffPsf.py

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# This file is part of meas_extensions_piff.
#
# Developed for the LSST Data Management System.
# This product includes software developed by the LSST Project
# (https://www.lsst.org).
# See the COPYRIGHT file at the top-level directory of this distribution
# for details of code ownership.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
__all__ = ["PiffPsf"]
 
import pickle
import numpy as np
from lsst.afw.typehandling import StorableHelperFactory
from lsst.meas.algorithms import ImagePsf
from lsst.afw.image import Image
from lsst.geom import Box2I, Point2I, Extent2I, Point2D
 
 
class PiffPsf(ImagePsf):
    _factory = StorableHelperFactory(
        "lsst.meas.extensions.piff.piffPsf",
        "PiffPsf"
    )
 
    def __init__(self, width, height, piffResult):
        assert width == height
        ImagePsf.__init__(self)
        self.width = width
        self.height = height
        self.dimensions = Extent2I(width, height)
        self._piffResult = piffResult
        self._averagePosition = None
 
    @property
    def piffResult(self):
        return self._piffResult
 
    # Storable overrides
 
    def isPersistable(self):
        return True
 
    def _getPersistenceName(self):
        return "PiffPsf"
 
    def _getPythonModule(self):
        return "lsst.meas.extensions.piff.piffPsf"
 
    def _write(self):
        return pickle.dumps((self.width, self.height, self._piffResult))
 
    @staticmethod
    def _read(pkl):
        return PiffPsf(*pickle.loads(pkl))
 
    # ImagePsf overrides
 
    def __deepcopy__(self, meta=None):
        return PiffPsf(self.width, self.height, self._piffResult)
 
    def resized(self, width, height):
        assert width == height
        return PiffPsf(width, height, self._piffResult)
 
    def _doComputeImage(self, position, color):
        return self._doImage(position, center=None)
 
    def _doComputeKernelImage(self, position, color):
        return self._doImage(position, center=True)
 
    def _doComputeBBox(self, position, color):
        return self._doBBox(Point2I(0, 0), center=True)
 
    def getAveragePosition(self):
        if self._averagePosition is None:
            x = np.mean([star.image_pos.x for star in self._piffResult.stars])
            y = np.mean([star.image_pos.y for star in self._piffResult.stars])
            self._averagePosition = Point2D(x, y)
        return self._averagePosition
 
    # Internal private methods
 
    def _doImage(self, position, center):
        # Follow Piff conventions for center.
        # None => draw as if star at position
        # True => draw in center of image
        gsimg = self._piffResult.draw(
            position.x, position.y, stamp_size=self.width, center=center
        )
        bbox = self._doBBox(position, center)
        img = Image(bbox, dtype=np.float64)
        img.array[:] = gsimg.array
        img.array /= np.sum(img.array)
        return img
 
    def _doBBox(self, position, center):
        origin = -(self.dimensions//2)
        if center is None:
            origin = Point2I(position) + origin
        return Box2I(Point2I(origin), self.dimensions)