def shift_mask(self, dx, dy, method='lanczos', order=5, cval=0.0):
'''Shift the mask of Stack object.
Parameters:
dx, dy (float): shift distance (in pixel) along x (horizontal) and y (vertical).
Note that elements in one row has the same y but different x.
Example: dx = 2 is to shift the image "RIGHT", dy = 3 is to shift the image "UP".
method (str): interpolation method. Use 'lanczos' or 'spline'.
order (int): the order of spline interpolation (within 0-5) or Lanczos interpolation (>0).
cval (scalar): value to fill the edges. Default is NaN.
Returns:
shift_mask: ndarray.
'''
if not hasattr(self, 'mask'):
raise AttributeError("This `Stack` object doesn't have `mask`!")
ny, nx = self.image.shape
if abs(dx) > nx or abs(ny) > ny:
raise ValueError('# Shift distance is beyond the image size.')
if method == 'lanczos':
try: # try to import galsim
from galsim import degrees, Angle
from galsim.interpolant import Lanczos
from galsim import Image, InterpolatedImage
from galsim.fitswcs import AstropyWCS
except:
raise ImportError(
'# Import `galsim` failed! Please check if `galsim` is installed!'
)
# Begin shift
assert (order > 0) and isinstance(
order,
int), 'order of ' + method + ' must be positive interger.'
galimg = InterpolatedImage(Image(self.mask, dtype=float),
scale=0.168,
x_interpolant=Lanczos(order))
galimg = galimg.shift(dx=dx * 0.168, dy=dy * 0.168)
result = galimg.drawImage(scale=0.168, nx=nx,
ny=ny) #, wcs=AstropyWCS(self.wcs))
self._mask = (result.array > 0.5).astype(float)
# Change the WCS of image
hdr = copy.deepcopy(self.header)
hdr['CRPIX1'] += dx
hdr['CRPIX2'] += dy
self.header = hdr
self.wcs = wcs.WCS(hdr)
return result.array
elif method == 'spline':
from scipy.ndimage.interpolation import shift
assert 0 < order <= 5 and isinstance(
order, int), 'order of ' + method + ' must be within 0-5.'
result = shift(self.mask, [dy, dx],
order=order,
mode='constant',
cval=cval)
self._mask = (result > 0.5).astype(float)
# Change the WCS of image
hdr = copy.deepcopy(self.header)
hdr['CRPIX1'] += dx
hdr['CRPIX2'] += dy
self.header = hdr
self.wcs = wcs.WCS(hdr)
return result
else:
raise ValueError(
"# Not supported interpolation method. Use 'lanczos' or 'spline'."
)
def shift_mask(self, dx, dy, method='iraf', order=5, cval=0.0):
'''Shift the mask of Celestial object.
Parameters:
dx, dy (float): shift distance (in pixel) along x (horizontal) and y (vertical).
Note that elements in one row has the same y but different x.
Example: dx = 2 is to shift the image "RIGHT", dy = 3 is to shift the image "UP".
method (str): interpolation method. Use 'lanczos' or 'spline' or 'iraf'
order (int): the order of spline interpolation (within 0-5) or Lanczos interpolation (>0).
cval (scalar): value to fill the edges. Default is NaN.
Returns:
shift_mask: ndarray.
'''
ny, nx = self.mask.shape
if abs(dx) > nx or abs(ny) > ny:
raise ValueError('# Shift distance is beyond the image size.')
if method == 'lanczos':
try: # try to import galsim
from galsim import degrees, Angle
from galsim.interpolant import Lanczos
from galsim import Image, InterpolatedImage
from galsim.fitswcs import AstropyWCS
except:
raise ImportError(
'# Import `galsim` failed! Please check if `galsim` is installed!'
)
# Begin shift
assert (order > 0) and isinstance(
order,
int), 'order of ' + method + ' must be positive interger.'
galimg = InterpolatedImage(Image(self.mask, dtype=float),
scale=self.pixel_scale,
x_interpolant=Lanczos(order))
galimg = galimg.shift(dx=dx * self.pixel_scale,
dy=dy * self.pixel_scale)
result = galimg.drawImage(scale=self.pixel_scale, nx=nx,
ny=ny) #, wcs=AstropyWCS(self.wcs))
self._mask = result.array
# Change the WCS of image
hdr = copy.deepcopy(self.header)
hdr['CRPIX1'] += dx
hdr['CRPIX2'] += dy
self.header = hdr
self.wcs = wcs.WCS(hdr)
self._wcs_header_merge()
return result.array
elif method == 'iraf':
self.save_to_fits('./_temp.fits', 'mask')
imshift('./_temp.fits',
'./_shift_temp.fits',
dx,
dy,
interp_type='poly3',
boundary_type='constant')
hdu = fits.open('./_shift_temp.fits')
self.mask = hdu[0].data
self.shape = hdu[0].data.shape
self.header = hdu[0].header
self.wcs = wcs.WCS(self.header)
hdu.close()
imdelete('./*temp.fits')
else:
raise ValueError(
"# Not supported interpolation method. Use 'lanczos' or 'iraf'."
)
def shift_mask(self, dx, dy, method='spline', order=5, cval=0.0):
'''Shift the mask of Celestial object.
Parameters:
dx (float): shift distance (in pixel) along x (horizontal).
Note that elements in one row has the same y but different x.
Example: dx = 2 is to shift the mask "RIGHT" (as seen in DS9), dy = 3 is to shift the image "UP".
dy (float): shift distance (in pixel) along y (vertical).
Note that elements in one row has the same y but different x.
Example: dx = 2 is to shift the mask "RIGHT" (as seen in DS9), dy = 3 is to shift the image "UP".
method (str): interpolation method. Use 'spline', lanczos' or 'iraf'.
If using 'iraf', default interpolation is 'poly3. 'Lanczos' requires ``GalSim`` installed.
order (int): the order of Spline or Lanczos interpolation (>0).
cval (float): value to fill the edges. Default is 0.
Returns:
shift_mask (ndarray): shifted mask. The "mask" attribute of ``Celestial`` class will also be changed accordingly.
'''
ny, nx = self.mask.shape
if abs(dx) > nx or abs(ny) > ny:
raise ValueError('# Shift distance is beyond the image size.')
if method == 'lanczos' or method == 'cubic' or method == 'quintic':
try: # try to import galsim
from galsim import degrees, Angle
from galsim.interpolant import Lanczos
from galsim import Image, InterpolatedImage
from galsim.fitswcs import AstropyWCS
except:
raise ImportError(
'# Import ``galsim`` failed! Please check if ``galsim`` is installed!'
)
# Begin shift
assert (order > 0) and isinstance(
order,
int), 'order of ' + method + ' must be positive interger.'
if method == 'lanczos':
galimg = InterpolatedImage(Image(self.image, dtype=float),
scale=self.pixel_scale,
x_interpolant=Lanczos(order))
else:
galimg = InterpolatedImage(Image(self.image, dtype=float),
scale=self.pixel_scale,
x_interpolant=method)
galimg = galimg.shift(dx=dx * self.pixel_scale,
dy=dy * self.pixel_scale)
result = galimg.drawImage(scale=self.pixel_scale, nx=nx,
ny=ny) #, wcs=AstropyWCS(self.wcs))
self._mask = result.array
# Change the WCS of image
hdr = copy.deepcopy(self.header)
hdr['CRPIX1'] += dx
hdr['CRPIX2'] += dy
self.header = hdr
self.wcs = wcs.WCS(self.header)
return result.array
elif method == 'iraf':
self.save_to_fits('./_temp.fits', 'mask')
imshift('./_temp.fits',
'./_shift_temp.fits',
dx,
dy,
interp_type='poly3',
boundary_type='constant')
hdu = fits.open('./_shift_temp.fits')
self.mask = hdu[0].data
self.shape = hdu[0].data.shape
self.header = hdu[0].header
self.wcs = wcs.WCS(self.header)
hdu.close()
imdelete('./*temp.fits')
return self.mask
elif method == 'spline':
from scipy.ndimage.interpolation import shift
assert 0 < order <= 5 and isinstance(
order, int), 'order of ' + method + ' must be within 0-5.'
result = shift(self.mask, [dy, dx],
order=order,
mode='constant',
cval=cval)
self._mask = result
# Change the WCS of image
hdr = copy.deepcopy(self.header)
hdr['CRPIX1'] += dx
hdr['CRPIX2'] += dy
self.header = hdr
self.wcs = wcs.WCS(self.header)
return result
else:
raise ValueError(
"# Not supported interpolation method. Use 'lanczos' or 'iraf'."
)