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dupeguru/py/modules/block/block.pyx

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# Created By: Virgil Dupras
# Created On: 2009-04-23
# $Id$
# Copyright 2009 Hardcoded Software (http://www.hardcoded.net)
cdef extern from "stdlib.h":
int abs(int n) # required so that abs() is applied on ints, not python objects
class NoBlocksError(Exception):
"""avgdiff/maxdiff has been called with empty lists"""
class DifferentBlockCountError(Exception):
"""avgdiff/maxdiff has been called with 2 block lists of different size."""
cdef object getblock(object image):
"""Returns a 3 sized tuple containing the mean color of 'image'.
image: a PIL image or crop.
"""
cdef int pixel_count, red, green, blue, r, g, b
if image.size[0]:
pixel_count = image.size[0] * image.size[1]
red = green = blue = 0
for r, g, b in image.getdata():
red += r
green += g
blue += b
return (red // pixel_count, green // pixel_count, blue // pixel_count)
else:
return (0, 0, 0)
def getblocks2(image, int block_count_per_side):
"""Returns a list of blocks (3 sized tuples).
image: A PIL image to base the blocks on.
block_count_per_side: This integer determine the number of blocks the function will return.
If it is 10, for example, 100 blocks will be returns (10 width, 10 height). The blocks will not
necessarely cover square areas. The area covered by each block will be proportional to the image
itself.
"""
if not image.size[0]:
return []
cdef int width, height, block_width, block_height, ih, iw, top, bottom, left, right
width, height = image.size
block_width = max(width // block_count_per_side, 1)
block_height = max(height // block_count_per_side, 1)
result = []
for ih in range(block_count_per_side):
top = min(ih * block_height, height - block_height)
bottom = top + block_height
for iw in range(block_count_per_side):
left = min(iw * block_width, width - block_width)
right = left + block_width
box = (left, top, right, bottom)
crop = image.crop(box)
result.append(getblock(crop))
return result
cdef int diff(first, second):
"""Returns the difference between the first block and the second.
It returns an absolute sum of the 3 differences (RGB).
"""
cdef int r1, g1, b1, r2, g2, b2
r1, g1, b1 = first
r2, g2, b2 = second
return abs(r1 - r2) + abs(g1 - g2) + abs(b1 - b2)
def avgdiff(first, second, int limit, int min_iterations):
"""Returns the average diff between first blocks and seconds.
If the result surpasses limit, limit + 1 is returned, except if less than min_iterations
iterations have been made in the blocks.
"""
cdef int count, sum, i, iteration_count
count = len(first)
if count != len(second):
raise DifferentBlockCountError()
if not count:
raise NoBlocksError()
sum = 0
for i in range(count):
iteration_count = i + 1
item1 = first[i]
item2 = second[i]
sum += diff(item1, item2)
if sum > limit * iteration_count and iteration_count >= min_iterations:
return limit + 1
result = sum // count
if (not result) and sum:
result = 1
return result