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# Licensed under a 3-clause BSD style license - see LICENSE.rst
from __future__ import (absolute_import, division, print_function,
unicode_literals)
import os
from ... import log
from ...io.fits import getdata
from ..mpl_normalize import simple_norm
def fits2bitmap(filename, ext=0, out_fn=None, stretch='linear',
power=1.0, asinh_a=0.1, min_cut=None, max_cut=None,
min_percent=None, max_percent=None, percent=None,
cmap='Greys_r'):
"""
Create a bitmap file from a FITS image, applying a stretching
transform between minimum and maximum cut levels and a matplotlib
colormap.
Parameters
----------
filename : str
The filename of the FITS file.
ext : int
FITS extension name or number of the image to convert. The
default is 0.
out_fn : str
The filename of the output bitmap image. The type of bitmap
is determined by the filename extension (e.g. '.jpg', '.png').
The default is a PNG file with the same name as the FITS file.
stretch : {{'linear', 'sqrt', 'power', log', 'asinh'}}
The stretching function to apply to the image. The default is
'linear'.
power : float, optional
The power index for ``stretch='power'``. The default is 1.0.
asinh_a : float, optional
For ``stretch='asinh'``, the value where the asinh curve
transitions from linear to logarithmic behavior, expressed as a
fraction of the normalized image. Must be in the range between
0 and 1. The default is 0.1.
min_cut : float, optional
The pixel value of the minimum cut level. Data values less than
``min_cut`` will set to ``min_cut`` before stretching the image.
The default is the image minimum. ``min_cut`` overrides
``min_percent``.
max_cut : float, optional
The pixel value of the maximum cut level. Data values greater
than ``min_cut`` will set to ``min_cut`` before stretching the
image. The default is the image maximum. ``max_cut`` overrides
``max_percent``.
min_percent : float, optional
The percentile value used to determine the pixel value of
minimum cut level. The default is 0.0. ``min_percent``
overrides ``percent``.
max_percent : float, optional
The percentile value used to determine the pixel value of
maximum cut level. The default is 100.0. ``max_percent``
overrides ``percent``.
percent : float, optional
The percentage of the image values used to determine the pixel
values of the minimum and maximum cut levels. The lower cut
level will set at the ``(100 - percent) / 2`` percentile, while
the upper cut level will be set at the ``(100 + percent) / 2``
percentile. The default is 100.0. ``percent`` is ignored if
either ``min_percent`` or ``max_percent`` is input.
cmap : str
The matplotlib color map name. The default is 'Greys_r'.
"""
import matplotlib.cm as cm
import matplotlib.image as mimg
# __main__ gives ext as a string
try:
ext = int(ext)
except ValueError:
pass
try:
image = getdata(filename, ext)
except Exception as e:
log.critical(e)
return 1
if image.ndim != 2:
log.critical('data in FITS extension {0} is not a 2D array'
.format(ext))
if out_fn is None:
out_fn = os.path.splitext(filename)[0]
if out_fn.endswith('.fits'):
out_fn = os.path.splitext(out_fn)[0]
out_fn += '.png'
if cmap not in cm.datad:
log.critical('{0} is not a valid matplotlib colormap name.'
.format(cmap))
return 1
norm = simple_norm(image, stretch=stretch, power=power, asinh_a=asinh_a,
min_cut=min_cut, max_cut=max_cut,
min_percent=min_percent, max_percent=max_percent,
percent=percent)
mimg.imsave(out_fn, norm(image), cmap=cmap)
log.info('Saved file to {0}.'.format(out_fn))
def main(args=None):
import argparse
parser = argparse.ArgumentParser(
description='Create a bitmap file from a FITS image.')
parser.add_argument('-e', '--ext', metavar='hdu', default=0,
help='Specify the HDU extension number or name '
'(Default is 0).')
parser.add_argument('-o', metavar='filename', type=str, default=None,
help='Filename for the output image (Default is a '
'PNG file with the same name as the FITS file).')
parser.add_argument('--stretch', type=str, default='linear',
help='Type of image stretching ("linear", "sqrt", '
'"power", "log", or "asinh") (Default is "linear").')
parser.add_argument('--power', type=float, default=1.0,
help='Power index for "power" stretching (Default is '
'1.0).')
parser.add_argument('--asinh_a', type=float, default=0.1,
help='The value in normalized image where the asinh '
'curve transitions from linear to logarithmic '
'behavior (used only for "asinh" stretch) '
'(Default is 0.1).')
parser.add_argument('--min_cut', type=float, default=None,
help='The pixel value of the minimum cut level '
'(Default is the image minimum).')
parser.add_argument('--max_cut', type=float, default=None,
help='The pixel value of the maximum cut level '
'(Default is the image maximum).')
parser.add_argument('--min_percent', type=float, default=None,
help='The percentile value used to determine the '
'minimum cut level (Default is 0).')
parser.add_argument('--max_percent', type=float, default=None,
help='The percentile value used to determine the '
'maximum cut level (Default is 100).')
parser.add_argument('--percent', type=float, default=None,
help='The percentage of the image values used to '
'determine the pixel values of the minimum and '
'maximum cut levels (Default is 100).')
parser.add_argument('--cmap', metavar='colormap_name', type=str,
default='Greys_r', help='matplotlib color map name '
'(Default is "Greys_r").')
parser.add_argument('filename', nargs='+',
help='Path to one or more FITS files to convert')
args = parser.parse_args(args)
for filename in args.filename:
fits2bitmap(filename, ext=args.ext, out_fn=args.o,
stretch=args.stretch, min_cut=args.min_cut,
max_cut=args.max_cut, min_percent=args.min_percent,
max_percent=args.max_percent, percent=args.percent,
power=args.power, asinh_a=args.asinh_a, cmap=args.cmap)
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