Viewing file:  FitsStubImagePlugin.py (2.5 KB) -rw-r--r--
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#
# The Python Imaging Library
# $Id$
#
# FITS stub adapter
#
# Copyright (c) 1998-2003 by Fredrik Lundh
#
# See the README file for information on usage and redistribution.
#
from . import Image, ImageFile
_handler = None
def register_handler(handler):
"""
Install application-specific FITS image handler.
:param handler: Handler object.
"""
global _handler
_handler = handler
# --------------------------------------------------------------------
# Image adapter
def _accept(prefix):
return prefix[:6] == b"SIMPLE"
class FITSStubImageFile(ImageFile.StubImageFile):
format = "FITS"
format_description = "FITS"
def _open(self):
offset = self.fp.tell()
headers = {}
while True:
header = self.fp.read(80)
if not header:
raise OSError("Truncated FITS file")
keyword = header[:8].strip()
if keyword == b"END":
break
value = header[8:].strip()
if value.startswith(b"="):
value = value[1:].strip()
if not headers and (not _accept(keyword) or value != b"T"):
raise SyntaxError("Not a FITS file")
headers[keyword] = value
naxis = int(headers[b"NAXIS"])
if naxis == 0:
raise ValueError("No image data")
elif naxis == 1:
self._size = 1, int(headers[b"NAXIS1"])
else:
self._size = int(headers[b"NAXIS1"]), int(headers[b"NAXIS2"])
number_of_bits = int(headers[b"BITPIX"])
if number_of_bits == 8:
self.mode = "L"
elif number_of_bits == 16:
self.mode = "I"
# rawmode = "I;16S"
elif number_of_bits == 32:
self.mode = "I"
elif number_of_bits in (-32, -64):
self.mode = "F"
# rawmode = "F" if number_of_bits == -32 else "F;64F"
self.fp.seek(offset)
loader = self._load()
if loader:
loader.open(self)
def _load(self):
return _handler
def _save(im, fp, filename):
if _handler is None or not hasattr("_handler", "save"):
raise OSError("FITS save handler not installed")
_handler.save(im, fp, filename)
# --------------------------------------------------------------------
# Registry
Image.register_open(FITSStubImageFile.format, FITSStubImageFile, _accept)
Image.register_save(FITSStubImageFile.format, _save)
Image.register_extensions(FITSStubImageFile.format, [".fit", ".fits"])
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