def test_pnmimage_quantize():
img = PNMImage(32, 32, 3)
for x in range(32):
for y in range(32):
img.set_xel_val(x, y, randint(0, 100), randint(50, 100), randint(0, 1))
hist = PNMImage.Histogram()
img.make_histogram(hist)
num_colors = hist.get_num_pixels()
assert num_colors > 100
img2 = PNMImage(img)
img2.quantize(100)
hist = PNMImage.Histogram()
img2.make_histogram(hist)
assert hist.get_num_pixels() <= 100
# Make sure that this is reasonably close
max_dist = 0
for x in range(32):
for y in range(32):
diff = img.get_xel(x, y) - img2.get_xel(x, y)
max_dist = max(max_dist, diff.length_squared())
# Also make sure that they are not out of range of the original
col = img2.get_xel_val(x, y)
assert col.r <= 100
assert col.g >= 50 and col.g <= 100
assert col.b in (0, 1)
assert max_dist < 0.1 ** 2
def _write_bitmap(self, fp, image, size, bpp):
""" Writes the bitmap header and data of an .ico file. """
fp.write(
struct.pack('<IiiHHIIiiII', 40, size, size * 2, 1, bpp, 0, 0, 0, 0,
0, 0))
# XOR mask
if bpp == 24:
# Align rows to 4-byte boundary
rowalign = b'\0' * (-(size * 3) & 3)
for y in xrange(size):
for x in xrange(size):
r, g, b = image.getXel(x, size - y - 1)
fp.write(
struct.pack('<BBB', int(b * 255), int(g * 255),
int(r * 255)))
fp.write(rowalign)
elif bpp == 32:
for y in xrange(size):
for x in xrange(size):
r, g, b, a = image.getXelA(x, size - y - 1)
fp.write(
struct.pack('<BBBB', int(b * 255), int(g * 255),
int(r * 255), int(a * 255)))
elif bpp == 8:
# We'll have to generate a palette of 256 colors.
hist = PNMImage.Histogram()
image2 = PNMImage(image)
if image2.hasAlpha():
image2.premultiplyAlpha()
image2.removeAlpha()
image2.quantize(256)
image2.make_histogram(hist)
colors = list(hist.get_pixels())
assert len(colors) <= 256
# Write the palette.
i = 0
while i < 256 and i < len(colors):
r, g, b, a = colors[i]
fp.write(struct.pack('<BBBB', b, g, r, 0))
i += 1
if i < 256:
# Fill the rest with zeroes.
fp.write(b'\x00' * (4 * (256 - i)))
# Write indices. Align rows to 4-byte boundary.
rowalign = b'\0' * (-size & 3)
for y in xrange(size):
for x in xrange(size):
pixel = image2.get_pixel(x, size - y - 1)
index = colors.index(pixel)
if index >= 256:
# Find closest pixel instead.
index = closest_indices[index - 256]
fp.write(struct.pack('<B', index))
fp.write(rowalign)
else:
raise ValueError("Invalid bpp %d" % (bpp))
# Create an AND mask, aligned to 4-byte boundary
if image.hasAlpha() and bpp <= 8:
rowalign = b'\0' * (-((size + 7) >> 3) & 3)
for y in xrange(size):
mask = 0
num_bits = 7
for x in xrange(size):
a = image.get_alpha_val(x, size - y - 1)
if a <= 1:
mask |= (1 << num_bits)
num_bits -= 1
if num_bits < 0:
fp.write(struct.pack('<B', mask))
mask = 0
num_bits = 7
if num_bits < 7:
fp.write(struct.pack('<B', mask))
fp.write(rowalign)
else:
andsize = (size + 7) >> 3
if andsize % 4 != 0:
andsize += 4 - (andsize % 4)
fp.write(b'\x00' * (andsize * size))