def testUnfilterScanlinePaeth(self):
"""This tests more edge cases in the paeth unfilter"""
scanprev = array('B', [2, 0, 0, 0, 9, 11])
scanline = array('B', [4, 6, 10, 9, 100, 101, 102])
filter_ = png.Filter(24, prev=scanprev)
out = filter_.undo_filter(scanline[0], scanline[1:])
self.assertEqual(list(out), [8, 10, 9, 108, 111, 113]) # paeth
def testUnfilterScanlinePaeth(self):
"""This tests more edge cases in the paeth unfilter"""
scanprev = array('B', [2, 0, 0, 0, 9, 11])
scanline = array('B', [4, 6, 10, 9, 100, 101, 102])
filter_ = png.Filter(24, prev=scanprev)
out = filter_.undo_filter(scanline[0], scanline[1:])
self.assertEqual(list(out), [8, 10, 9, 108, 111, 113]) # paeth
def testFilterScanline(self):
"""Test filtering with previous line"""
prev = array('B', [20, 21, 22, 210, 211, 212])
line = array('B', [30, 32, 34, 230, 233, 236])
filter_ = png.Filter(24, prev=prev)
res = filter_.filter_all(line)
# None
self.assertEqual(list(res[0]), [0, 30, 32, 34, 230, 233, 236])
# sub
self.assertEqual(list(res[1]), [1, 30, 32, 34, 200, 201, 202])
# up
self.assertEqual(list(res[2]), [2, 10, 11, 12, 20, 22, 24])
# average
self.assertEqual(list(res[3]), [3, 20, 22, 23, 110, 112, 113])
# paeth
self.assertEqual(list(res[4]),
[4, self.paeth(30, 0, 20, 0), self.paeth(32, 0, 21, 0),
self.paeth(34, 0, 22, 0), self.paeth(230, 30, 210, 20),
self.paeth(233, 32, 211, 21), self.paeth(236, 34, 212, 22)])
def testUnfilterScanline(self):
"""Test unfiltering"""
scanprev = array('B', [20, 21, 22, 210, 211, 212])
scanline = array('B', [30, 32, 34, 230, 233, 236])
def undo_filter(filter_type, line, prev):
"""undoing filter"""
filter_ = png.Filter(24, prev=prev)
line = array('B', line)
return filter_.undo_filter(filter_type, line)
out = undo_filter(0, scanline, scanprev)
self.assertEqual(list(out), list(scanline)) # none
out = undo_filter(1, scanline, scanprev)
self.assertEqual(list(out), [30, 32, 34, 4, 9, 14]) # sub
out = undo_filter(2, scanline, scanprev)
self.assertEqual(list(out), [50, 53, 56, 184, 188, 192]) # up
out = undo_filter(3, scanline, scanprev)
self.assertEqual(list(out), [40, 42, 45, 99, 103, 108]) # average
out = undo_filter(4, scanline, scanprev)
self.assertEqual(list(out), [50, 53, 56, 184, 188, 192]) # paeth
def testL2(self):
"""Test L with depth 2. Also tests asRGB8."""
w = png.Writer(1, 4, greyscale=True, bitdepth=2)
f = BytesIO()
w.write_array(f, array('B', range(4)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels, _ = r.asRGB8()
self.assertEqual(x, 1)
self.assertEqual(y, 4)
for i, row in enumerate(pixels):
self.assertEqual(len(row), 3)
self.assertEqual(list(row), [0x55 * i] * 3)
def testL2(self):
"""Test L with depth 2. Also tests asRGB8."""
w = png.Writer(1, 4, greyscale=True, bitdepth=2)
f = BytesIO()
w.write_array(f, array('B', range(4)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels, _ = r.asRGB8()
self.assertEqual(x, 1)
self.assertEqual(y, 4)
for i, row in enumerate(pixels):
self.assertEqual(len(row), 3)
self.assertEqual(list(row), [0x55 * i] * 3)
def testUnfilterScanline(self):
"""Test unfiltering"""
scanprev = array('B', [20, 21, 22, 210, 211, 212])
scanline = array('B', [30, 32, 34, 230, 233, 236])
def undo_filter(filter_type, line, prev):
"""undoing filter"""
filter_ = png.Filter(24, prev=prev)
line = array('B', line)
return filter_.undo_filter(filter_type, line)
out = undo_filter(0, scanline, scanprev)
self.assertEqual(list(out), list(scanline)) # none
out = undo_filter(1, scanline, scanprev)
self.assertEqual(list(out), [30, 32, 34, 4, 9, 14]) # sub
out = undo_filter(2, scanline, scanprev)
self.assertEqual(list(out), [50, 53, 56, 184, 188, 192]) # up
out = undo_filter(3, scanline, scanprev)
self.assertEqual(list(out), [40, 42, 45, 99, 103, 108]) # average
out = undo_filter(4, scanline, scanprev)
self.assertEqual(list(out), [50, 53, 56, 184, 188, 192]) # paeth
def helperLN(self, n):
"""Helper for L-tests"""
mask = (1 << n) - 1
# Use small chunk_limit so that multiple chunk writing is tested.
w = png.Writer(15, 17, greyscale=True, bitdepth=n, chunk_limit=99)
f = BytesIO()
w.write_array(f, array('B', [mask & it for it in range(1, 256)]))
r = png.Reader(bytes=f.getvalue())
x, y, pixels, _ = r.read()
self.assertEqual(x, 15)
self.assertEqual(y, 17)
self.assertEqual(list(itertools.chain(*pixels)),
[mask & it for it in range(1, 256)])
def helperLN(self, n):
"""Helper for L-tests"""
mask = (1 << n) - 1
# Use small chunk_limit so that multiple chunk writing is tested.
w = png.Writer(15, 17, greyscale=True, bitdepth=n, chunk_limit=99)
f = BytesIO()
w.write_array(f, array('B', [mask & it for it in range(1, 256)]))
r = png.Reader(bytes=f.getvalue())
x, y, pixels, _ = r.read()
self.assertEqual(x, 15)
self.assertEqual(y, 17)
self.assertEqual(list(itertools.chain(*pixels)),
[mask & it for it in range(1, 256)])
def testP2(self):
"""2-bit palette."""
a = (255, 255, 255)
b = (200, 120, 120)
c = (50, 99, 50)
w = png.Writer(1, 4, bitdepth=2, palette=[a, b, c])
f = BytesIO()
w.write_array(f, array('B', (0, 1, 1, 2)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels = r.asRGB8()[:3]
self.assertEqual(x, 1)
self.assertEqual(y, 4)
self.assertEqual([list(p) for p in pixels],
[list(p) for p in (a, b, b, c)])
def testP2(self):
"""2-bit palette."""
a = (255, 255, 255)
b = (200, 120, 120)
c = (50, 99, 50)
w = png.Writer(1, 4, bitdepth=2, palette=[a, b, c])
f = BytesIO()
w.write_array(f, array('B', (0, 1, 1, 2)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels = r.asRGB8()[:3]
self.assertEqual(x, 1)
self.assertEqual(y, 4)
self.assertEqual([list(p) for p in pixels],
[list(p) for p in (a, b, b, c)])
def testFilterScanline(self):
"""Test filtering with previous line"""
prev = array('B', [20, 21, 22, 210, 211, 212])
line = array('B', [30, 32, 34, 230, 233, 236])
filter_ = png.Filter(24, prev=prev)
res = filter_.filter_all(line)
# None
self.assertEqual(list(res[0]), [0, 30, 32, 34, 230, 233, 236])
# sub
self.assertEqual(list(res[1]), [1, 30, 32, 34, 200, 201, 202])
# up
self.assertEqual(list(res[2]), [2, 10, 11, 12, 20, 22, 24])
# average
self.assertEqual(list(res[3]), [3, 20, 22, 23, 110, 112, 113])
# paeth
self.assertEqual(list(res[4]), [
4,
self.paeth(30, 0, 20, 0),
self.paeth(32, 0, 21, 0),
self.paeth(34, 0, 22, 0),
self.paeth(230, 30, 210, 20),
self.paeth(233, 32, 211, 21),
self.paeth(236, 34, 212, 22)
])
def testFilterScanlineFirstLine(self):
"""Test filter without previous line"""
line = array('B', [30, 31, 32, 230, 231, 232])
filter_ = png.Filter(24, prev=None)
res = filter_.filter_all(line)
# none
self.assertEqual(list(res[0]), [0, 30, 31, 32, 230, 231, 232])
# sub
self.assertEqual(list(res[1]), [1, 30, 31, 32, 200, 200, 200])
# up
self.assertEqual(list(res[2]), [2, 30, 31, 32, 230, 231, 232])
# average
self.assertEqual(list(res[3]), [3, 30, 31, 32, 215, 216, 216])
# paeth
self.assertEqual(list(res[4]),
[4, self.paeth(30, 0, 0, 0), self.paeth(31, 0, 0, 0),
self.paeth(32, 0, 0, 0), self.paeth(230, 30, 0, 0),
self.paeth(231, 31, 0, 0), self.paeth(232, 32, 0, 0)])
def ascii_scanlines(infile, width, height, planes, bitdepth):
"""
Generates boxed rows in flat pixel format, from the input file.
It assumes that the input file is in a "Netpbm-like"
ASCII format, and is positioned at the beginning of the first
pixel. The number of pixels to read is taken from the image
dimensions (`width`, `height`, `planes`) and the number of bytes
per value is implied by the image `bitdepth`.
"""
# Values per row
vpr = width * planes
if bitdepth > 8:
assert bitdepth == 16
typecode = 'H'
else:
typecode = 'B'
for _ in range(height):
line = read_int_tokens(infile, vpr, True)
yield array(typecode, line)
def ascii_scanlines(infile, width, height, planes, bitdepth):
"""
Generates boxed rows in flat pixel format, from the input file.
It assumes that the input file is in a "Netpbm-like"
ASCII format, and is positioned at the beginning of the first
pixel. The number of pixels to read is taken from the image
dimensions (`width`, `height`, `planes`) and the number of bytes
per value is implied by the image `bitdepth`.
"""
# Values per row
vpr = width * planes
if bitdepth > 8:
assert bitdepth == 16
typecode = 'H'
else:
typecode = 'B'
for _ in range(height):
line = read_int_tokens(infile, vpr, True)
yield array(typecode, line)
def testPtrns(self):
"""Test colour type 3 and tRNS chunk (and 4-bit palette)."""
a = (50, 99, 50, 50)
b = (200, 120, 120, 80)
c = (255, 255, 255)
d = (200, 120, 120)
e = (50, 99, 50)
w = png.Writer(3, 3, bitdepth=4, palette=[a, b, c, d, e])
f = BytesIO()
w.write_array(f, array('B', (4, 3, 2, 3, 2, 0, 2, 0, 1)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels = r.asRGBA8()[:3]
self.assertEqual(x, 3)
self.assertEqual(y, 3)
c = c + (255, )
d = d + (255, )
e = e + (255, )
boxed = [(e, d, c), (d, c, a), (c, a, b)]
flat = [itertools.chain(*row) for row in boxed]
self.assertEqual([list(it) for it in pixels],
[list(it) for it in flat])
def testPtrns(self):
"""Test colour type 3 and tRNS chunk (and 4-bit palette)."""
a = (50, 99, 50, 50)
b = (200, 120, 120, 80)
c = (255, 255, 255)
d = (200, 120, 120)
e = (50, 99, 50)
w = png.Writer(3, 3, bitdepth=4, palette=[a, b, c, d, e])
f = BytesIO()
w.write_array(f, array('B', (4, 3, 2, 3, 2, 0, 2, 0, 1)))
r = png.Reader(bytes=f.getvalue())
x, y, pixels = r.asRGBA8()[:3]
self.assertEqual(x, 3)
self.assertEqual(y, 3)
c = c + (255,)
d = d + (255,)
e = e + (255,)
boxed = [(e, d, c), (d, c, a), (c, a, b)]
flat = [itertools.chain(*row) for row in boxed]
self.assertEqual([list(it) for it in pixels],
[list(it) for it in flat])
def testFilterScanlineFirstLine(self):
"""Test filter without previous line"""
line = array('B', [30, 31, 32, 230, 231, 232])
filter_ = png.Filter(24, prev=None)
res = filter_.filter_all(line)
# none
self.assertEqual(list(res[0]), [0, 30, 31, 32, 230, 231, 232])
# sub
self.assertEqual(list(res[1]), [1, 30, 31, 32, 200, 200, 200])
# up
self.assertEqual(list(res[2]), [2, 30, 31, 32, 230, 231, 232])
# average
self.assertEqual(list(res[3]), [3, 30, 31, 32, 215, 216, 216])
# paeth
self.assertEqual(list(res[4]), [
4,
self.paeth(30, 0, 0, 0),
self.paeth(31, 0, 0, 0),
self.paeth(32, 0, 0, 0),
self.paeth(230, 30, 0, 0),
self.paeth(231, 31, 0, 0),
self.paeth(232, 32, 0, 0)
])
def line():
return array('H', struct.unpack(fmt, infile.read(row_bytes)))
def undo_filter(filter_type, line, prev):
"""undoing filter"""
filter_ = png.Filter(24, prev=prev)
line = array('B', line)
return filter_.undo_filter(filter_type, line)
def line():
return array('H', struct.unpack(fmt, infile.read(row_bytes)))
def undo_filter(filter_type, line, prev):
"""undoing filter"""
filter_ = png.Filter(24, prev=prev)
line = array('B', line)
return filter_.undo_filter(filter_type, line)