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#cython: boundscheck=False
#cython: wraparound=False
from libc.stdlib cimport abs as c_abs
cimport cpython.array
# TODO: I don't know how can I not return any value (void doesn't work)
cpdef int undo_filter_sub(int filter_unit, unsigned char[:] scanline,
unsigned char[:] previous, unsigned char[:] result) nogil:
"""Undo sub filter."""
cdef int l = result.shape[0]
cdef int ai = 0
cdef unsigned char x, a
# Loops starts at index fu. Observe that the initial part
# of the result is already filled in correctly with
# scanline.
for i in range(filter_unit, l):
x = scanline[i]
a = result[ai]
result[i] = (x + a) & 0xff
ai += 1
return 0
cpdef int undo_filter_up(int filter_unit, unsigned char[:] scanline,
unsigned char[:] previous, unsigned char[:] result) nogil:
"""Undo up filter."""
cdef int i
cdef int l = result.shape[0]
cdef unsigned char x, b
for i in range(l):
x = scanline[i]
b = previous[i]
result[i] = (x + b) & 0xff
return 0
cpdef int undo_filter_average(int filter_unit, unsigned char[:] scanline,
unsigned char[:] previous, unsigned char[:] result) nogil:
"""Undo up filter."""
cdef int i, ai
cdef int l = result.shape[0]
cdef unsigned char x, a, b
ai = -filter_unit
for i in range(l):
x = scanline[i]
if ai < 0:
a = 0
else:
a = result[ai]
b = previous[i]
result[i] = (x + ((a + b) >> 1)) & 0xff
ai += 1
return 0
cpdef int undo_filter_paeth(int filter_unit, unsigned char[:] scanline,
unsigned char[:] previous, unsigned char[:] result) nogil:
"""Undo Paeth filter."""
# Also used for ci.
cdef int ai = -filter_unit
cdef int l = result.shape[0]
cdef int i, pa, pb, pc, p
cdef unsigned char x, a, b, c, pr
for i in range(l):
x = scanline[i]
if ai < 0:
a = c = 0
else:
a = result[ai]
c = previous[ai]
b = previous[i]
p = a + b - c
pa = c_abs(p - a)
pb = c_abs(p - b)
pc = c_abs(p - c)
if pa <= pb and pa <= pc:
pr = a
elif pb <= pc:
pr = b
else:
pr = c
result[i] = (x + pr) & 0xff
ai += 1
return 0
cpdef int convert_rgb_to_rgba(unsigned char[:] row, unsigned char[:] result) nogil:
cdef int i, l, j, k
l = min(row.shape[0] / 3, result.shape[0] / 4)
for i in range(l):
j = i * 3
k = i * 4
result[k] = row[j]
result[k + 1] = row[j + 1]
result[k + 2] = row[j + 2]
return 0
cpdef int convert_l_to_rgba(unsigned char[:] row, unsigned char[:] result) nogil:
cdef int i, l, j, k, lum
l = min(row.shape[0], result.shape[0] / 4)
for i in range(l):
j = i
k = i * 4
lum = row[j]
result[k] = lum
result[k + 1] = lum
result[k + 2] = lum
return 0
cpdef int convert_la_to_rgba(unsigned char[:] row, unsigned char[:] result) nogil:
cdef int i, l, j, k, lum
l = min(row.shape[0] / 2, result.shape[0] / 4)
for i in range(l):
j = i * 2
k = i * 4
lum = row[j]
result[k] = lum
result[k + 1] = lum
result[k + 2] = lum
result[k + 3] = row[j + 1]
return 0
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