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Speed up of about 33%, maybe? #210

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Added a real fix for #209, seeing about a 22% speed up there.
This commit is contained in:
John Evans 2014-04-02 11:28:00 -04:00
commit eb1df90fb9
1 changed files with 14 additions and 18 deletions
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32
glymur/jp2box.py
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@ -1882,21 +1882,14 @@ class PaletteBox(Jp2kBox):
fptr.write(write_buffer)
bps = self.bits_per_component
if any(b != bps[0] for b in bps):
if all(b == bps[0] for b in bps):
# All components are the same. Writing is straightforward.
if self.bits_per_component[0] <= 8:
code = 'B'
dtype = np.uint8
write_buffer = np.getbuffer(self.palette.astype(np.uint8))
elif self.bits_per_component[0] <= 16:
code = 'H'
dtype = np.uint16
write_buffer = np.getbuffer(self.palette.astype(np.uint16))
elif self.bits_per_component[0] <= 32:
code = 'I'
dtype = np.uint32
nelts = self.palette.shape[0] * self.palette.shape[1]
fmt = '>{0}{1}'.format(nelts, code)
write_buffer = struct.pack(fmt,
self.palette.astype(dtype).flatten())
write_buffer = np.getbuffer(self.palette.astype(np.uint32))
fptr.write(write_buffer)
else:
# Not all the components are the same. More general, but much rarer
@ -1937,19 +1930,22 @@ class PaletteBox(Jp2kBox):
bps = [((x & 0x7f) + 1) for x in bps_signed]
signed = [((x & 0x80) > 1) for x in bps_signed]
if any(b != bps_signed[0] for b in bps_signed):
if all(b == bps_signed[0] for b in bps_signed):
# Ok the palette has the same datatype for all columns. We should
# be able to efficiently read it.
if bps <= 8:
if bps[0] <= 8:
nbytes_per_row = num_columns
dtype = np.uint8
elif bps <= 16:
elif bps[0] <= 16:
nbytes_per_row = 2 * num_columns
dtype = np.uint16
elif bps <= 32:
elif bps[0] <= 32:
nbytes_per_row = 3 * num_columns
dtype = np.uint32
read_buffer = fptr.read(num_entries * np.sum(bps) / 8)
palette = np.frombuffer(read_buffer, dtype)
palette.reshape((num_entries, num_columns))
read_buffer = fptr.read(num_entries * nbytes_per_row)
palette = np.frombuffer(read_buffer, dtype=dtype)
palette = np.reshape(palette, (num_entries, num_columns))
else:
# General case where the columns may not be the same width.