def __init__(self, fp, stop_when=None, force=False):
"""Read the preambleand meta info, prepare iterator for remainder
fp -- an open DicomFileLike object, at start of file
Adds flags to fp: Big/Little-endian and Implicit/Explicit VR
"""
self.fp = fp
self.stop_when = stop_when
self.preamble = preamble = read_preamble(fp, force)
self.has_header = has_header = (preamble is not None)
self.file_meta_info = Dataset()
if has_header:
self.file_meta_info = file_meta_info = _read_file_meta_info(fp)
transfer_syntax = file_meta_info.TransferSyntaxUID
if transfer_syntax == dicom.UID.ExplicitVRLittleEndian:
self._is_implicit_VR = False
self._is_little_endian = True
elif transfer_syntax == dicom.UID.ImplicitVRLittleEndian:
self._is_implicit_VR = True
self._is_little_endian = True
elif transfer_syntax == dicom.UID.ExplicitVRBigEndian:
self._is_implicit_VR = False
self._is_little_endian = False
elif transfer_syntax == dicom.UID.DeflatedExplicitVRLittleEndian:
# See PS3.6-2008 A.5 (p 71) -- when written, the entire dataset following
# the file metadata was prepared the normal way, then "deflate" compression applied.
# All that is needed here is to decompress and then use as normal in a file-like object
zipped = fp.read()
# -MAX_WBITS part is from comp.lang.python answer: http://groups.google.com/group/comp.lang.python/msg/e95b3b38a71e6799
unzipped = zlib.decompress(zipped, -zlib.MAX_WBITS)
fp = StringIO(unzipped) # a file-like object that usual code can use as normal
self.fp = fp #point to new object
self._is_implicit_VR = False
self._is_little_endian = True
else:
# Any other syntax should be Explicit VR Little Endian,
# e.g. all Encapsulated (JPEG etc) are ExplVR-LE by Standard PS 3.5-2008 A.4 (p63)
self._is_implicit_VR = False
self._is_little_endian = True
else: # no header -- make assumptions
fp.TransferSyntaxUID = dicom.UID.ImplicitVRLittleEndian
self._is_little_endian = True
self._is_implicit_VR = True
logger.debug("Using %s VR, %s Endian transfer syntax" %(("Explicit", "Implicit")[self._is_implicit_VR], ("Big", "Little")[self._is_little_endian]))
def __init__(self, fp, stop_when=None, force=False):
"""Read the preambleand meta info, prepare iterator for remainder
fp -- an open DicomFileLike object, at start of file
Adds flags to fp: Big/Little-endian and Implicit/Explicit VR
"""
self.fp = fp
self.stop_when = stop_when
self.preamble = preamble = read_preamble(fp, force)
self.has_header = has_header = (preamble is not None)
self.file_meta_info = Dataset()
if has_header:
self.file_meta_info = file_meta_info = _read_file_meta_info(fp)
transfer_syntax = file_meta_info.TransferSyntaxUID
if transfer_syntax == dicom.UID.ExplicitVRLittleEndian:
self._is_implicit_VR = False
self._is_little_endian = True
elif transfer_syntax == dicom.UID.ImplicitVRLittleEndian:
self._is_implicit_VR = True
self._is_little_endian = True
elif transfer_syntax == dicom.UID.ExplicitVRBigEndian:
self._is_implicit_VR = False
self._is_little_endian = False
elif transfer_syntax == dicom.UID.DeflatedExplicitVRLittleEndian:
# See PS3.6-2008 A.5 (p 71) -- when written, the entire dataset following
# the file metadata was prepared the normal way, then "deflate" compression applied.
# All that is needed here is to decompress and then use as normal in a file-like object
zipped = fp.read()
# -MAX_WBITS part is from comp.lang.python answer: http://groups.google.com/group/comp.lang.python/msg/e95b3b38a71e6799
unzipped = zlib.decompress(zipped, -zlib.MAX_WBITS)
fp = StringIO(unzipped) # a file-like object that usual code can use as normal
self.fp = fp #point to new object
self._is_implicit_VR = False
self._is_little_endian = True
else:
# Any other syntax should be Explicit VR Little Endian,
# e.g. all Encapsulated (JPEG etc) are ExplVR-LE by Standard PS 3.5-2008 A.4 (p63)
self._is_implicit_VR = False
self._is_little_endian = True
else: # no header -- make assumptions
fp.TransferSyntaxUID = dicom.UID.ImplicitVRLittleEndian
self._is_little_endian = True
self._is_implicit_VR = True
logger.debug("Using %s VR, %s Endian transfer syntax" %(("Explicit", "Implicit")[self._is_implicit_VR], ("Big", "Little")[self._is_little_endian]))
