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colr, flst, and pclr box. #130

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The pclr box is the problematic one.  If the box length is wrong, then
it's hard to reliably parse when reading just one raw buffer.
This commit is contained in:
jevans 2014-03-03 20:49:00 -05:00
commit bf0d94e65b
1 changed files with 25 additions and 23 deletions
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48
glymur/jp2box.py
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@ -401,28 +401,30 @@ class ColourSpecificationBox(Jp2kBox):
-------
ColourSpecificationBox instance
"""
num_bytes = offset + length - fptr.tell()
read_buffer = fptr.read(num_bytes)
# Read the brand, minor version.
read_buffer = fptr.read(3)
(method, precedence, approximation) = struct.unpack('>BBB',
read_buffer)
(method, precedence, approximation) = struct.unpack_from('>BBB',
read_buffer,
0)
if method == 1:
# enumerated colour space
read_buffer = fptr.read(4)
colorspace, = struct.unpack('>I', read_buffer)
colorspace, = struct.unpack_from('>I', read_buffer, 3)
icc_profile = None
else:
# ICC profile
colorspace = None
numbytes = offset + length - fptr.tell()
if numbytes < 128:
if num_bytes < 131:
# If the number of bytes is less than 128 + 3, then there
# cannot possibly be enough for an ICC profile.
msg = "ICC profile header is corrupt, length is "
msg += "only {0} instead of 128."
warnings.warn(msg.format(numbytes), UserWarning)
warnings.warn(msg.format(num_bytes - 3), UserWarning)
icc_profile = None
else:
profile = _ICCProfile(fptr.read(numbytes))
profile = _ICCProfile(read_buffer[3:])
icc_profile = profile.header
box = ColourSpecificationBox(method=method,
@ -1245,7 +1247,7 @@ class FragmentListBox(Jp2kBox):
@staticmethod
def parse(fptr, offset, length):
"""Parse JPX free box.
"""Parse JPX fragment list box.
Parameters
----------
@ -1260,11 +1262,13 @@ class FragmentListBox(Jp2kBox):
-------
FragmentListBox instance
"""
read_buffer = fptr.read(2)
num_fragments, = struct.unpack('>H', read_buffer)
num_bytes = offset + length - fptr.tell()
read_buffer = fptr.read(num_bytes)
num_fragments, = struct.unpack_from('>H', read_buffer, offset=0)
read_buffer = fptr.read(num_fragments * 14)
lst = struct.unpack('>' + 'QIH' * num_fragments, read_buffer)
lst = struct.unpack_from('>' + 'QIH' * num_fragments,
read_buffer,
offset=2)
frag_offset = lst[0::3]
frag_len = lst[1::3]
data_reference = lst[2::3]
@ -1826,13 +1830,12 @@ class PaletteBox(Jp2kBox):
-------
PaletteBox instance
"""
# Get the size of the palette.
read_buffer = fptr.read(3)
(num_entries, num_columns) = struct.unpack('>HB', read_buffer)
num_bytes = offset + length - fptr.tell()
read_buffer = fptr.read(num_bytes)
(nrows, ncols) = struct.unpack_from('>HB', read_buffer, offset=0)
# Need to determine bps and signed or not
read_buffer = fptr.read(num_columns)
data = struct.unpack('>' + 'B' * num_columns, read_buffer)
data = struct.unpack_from('>' + 'B' * ncols, read_buffer, offset=3)
bps = [((x & 0x7f) + 1) for x in data]
signed = [((x & 0x80) > 1) for x in data]
@ -1849,11 +1852,10 @@ class PaletteBox(Jp2kBox):
# That means a list comprehension does this in one shot.
row_nbytes = sum([int(math.ceil(x/8.0)) for x in bps])
read_buffer = fptr.read(num_entries * row_nbytes)
palette = np.zeros((num_entries, num_columns), dtype=np.int32)
for j in range(num_entries):
palette = np.zeros((nrows, ncols), dtype=np.int32)
for j in range(nrows):
palette[j] = struct.unpack_from(fmt, read_buffer,
offset=j * row_nbytes)
offset=j * row_nbytes + 3 + ncols)
return PaletteBox(palette, bps, signed, length=length, offset=offset)