def test_not_little_endian(self):
"""Test reading big endian raises exception"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = False
with pytest.raises(ValueError,
match="'fp.is_little_endian' must be True"):
get_frame_offsets(fp)
def test_not_little_endian(self):
"""Test reading big endian raises exception"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = False
with pytest.raises(ValueError,
match="'fp.is_little_endian' must be True"):
get_frame_offsets(fp)
def test_bad_length_multiple(self):
"""Test raises exception if the item length is not a multiple of 4."""
# Length 10
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x0A\x00\x00\x00' \
b'\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
with pytest.raises(ValueError,
match="The length of the Basic Offset Table item"
" is not a multiple of 4."):
get_frame_offsets(fp)
def test_bad_tag(self):
"""Test raises exception if no item tag."""
# (fffe,e100)
bytestream = b'\xFE\xFF\x00\xE1' \
b'\x08\x00\x00\x00' \
b'\x01\x02\x03\x04\x05\x06\x07\x08'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
with pytest.raises(ValueError,
match="Unexpected tag '\(fffe, e100\)' when "
"parsing the Basic Table Offset item."):
get_frame_offsets(fp)
def test_bad_length_multiple(self):
"""Test raises exception if the item length is not a multiple of 4."""
# Length 10
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x0A\x00\x00\x00' \
b'\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
with pytest.raises(ValueError,
match="The length of the Basic Offset Table item"
" is not a multiple of 4."):
get_frame_offsets(fp)
def test_bad_tag(self):
"""Test raises exception if no item tag."""
# (fffe,e100)
bytestream = b'\xFE\xFF\x00\xE1' \
b'\x08\x00\x00\x00' \
b'\x01\x02\x03\x04\x05\x06\x07\x08'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
with pytest.raises(ValueError,
match="Unexpected tag '\(fffe, e100\)' when "
"parsing the Basic Table Offset item."):
get_frame_offsets(fp)
def test_zero_length(self):
"""Test reading BOT with zero length"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0] == get_frame_offsets(fp)
def test_encapsulate_single_fragment_per_frame_bot(self):
"""Test encapsulating single fragment per frame with BOT values."""
ds = dcmread(JP2K_10FRAME_NOBOT)
frames = decode_data_sequence(ds.PixelData)
assert len(frames) == 10
data = encapsulate(frames, fragments_per_frame=1, has_bot=True)
test_frames = decode_data_sequence(data)
for a, b in zip(test_frames, frames):
assert a == b
fp = DicomBytesIO(data)
fp.is_little_endian = True
length, offsets = get_frame_offsets(fp)
assert offsets == [
0x0000, # 0
0x0eee, # 3822
0x1df6, # 7670
0x2cf8, # 11512
0x3bfc, # 15356
0x4ade, # 19166
0x59a2, # 22946
0x6834, # 26676
0x76e2, # 30434
0x8594 # 34196
]
def test_zero_length(self):
"""Test reading BOT with zero length"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0] == get_frame_offsets(fp)
def test_encapsulate_single_fragment_per_frame_bot(self):
"""Test encapsulating single fragment per frame with BOT values."""
ds = dcmread(JP2K_10FRAME_NOBOT)
frames = decode_data_sequence(ds.PixelData)
assert len(frames) == 10
data = encapsulate(frames, fragments_per_frame=1, has_bot=True)
test_frames = decode_data_sequence(data)
for a, b in zip(test_frames, frames):
assert a == b
fp = DicomBytesIO(data)
fp.is_little_endian = True
offsets = get_frame_offsets(fp)
assert offsets == [
0x0000, # 0
0x0eee, # 3822
0x1df6, # 7670
0x2cf8, # 11512
0x3bfc, # 15356
0x4ade, # 19166
0x59a2, # 22946
0x6834, # 26676
0x76e2, # 30434
0x8594 # 34196
]
def test_single_frame(self):
"""Test reading single-frame BOT item"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x04\x00\x00\x00' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0] == get_frame_offsets(fp)
def test_single_frame(self):
"""Test reading single-frame BOT item"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x04\x00\x00\x00' \
b'\x00\x00\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0] == get_frame_offsets(fp)
def test_multi_frame(self):
"""Test reading multi-frame BOT item"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x10\x00\x00\x00' \
b'\x00\x00\x00\x00' \
b'\x66\x13\x00\x00' \
b'\xF4\x25\x00\x00' \
b'\xFE\x37\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0, 4966, 9716, 14334] == get_frame_offsets(fp)
def test_multi_frame(self):
"""Test reading multi-frame BOT item"""
bytestream = b'\xFE\xFF\x00\xE0' \
b'\x10\x00\x00\x00' \
b'\x00\x00\x00\x00' \
b'\x66\x13\x00\x00' \
b'\xF4\x25\x00\x00' \
b'\xFE\x37\x00\x00'
fp = DicomBytesIO(bytestream)
fp.is_little_endian = True
assert [0, 4966, 9716, 14334] == get_frame_offsets(fp)
def _read_bot(fp: DicomFile) -> List[int]:
"""Reads the Basic Offset Table (BOT) item of an encapsulated Pixel Data
element.
Parameters
----------
fp: pydicom.filebase.DicomFile
Pointer for DICOM PS3.10 file stream positioned at the first byte of
the Pixel Data element
Returns
-------
List[int]
Offset of each Frame item in bytes from the first byte of the Pixel Data
element following the BOT item
Note
----
Moves the pointer to the first byte of the open file following the BOT item
(the first byte of the first Frame item).
Raises
------
IOError
When file pointer is not positioned at first byte of Pixel Data element
"""
tag = TupleTag(fp.read_tag())
if int(tag) not in _PIXEL_DATA_TAGS:
raise IOError(
'Expected file pointer at first byte of Pixel Data element.')
# Skip Pixel Data element header (tag, VR, length)
pixel_data_element_value_offset = data_element_offset_to_value(
fp.is_implicit_VR, 'OB')
fp.seek(pixel_data_element_value_offset - 4, 1)
is_empty, offsets = get_frame_offsets(fp)
return offsets
