From 7ab4a4d6f5575f114d16dc06cfa152b3b3a51db0 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 13 Nov 2011 19:47:28 -0500
Subject: Initial commit.

---
 unshred-binary-merge-failure.py | 81 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100755 unshred-binary-merge-failure.py

(limited to 'unshred-binary-merge-failure.py')

diff --git a/unshred-binary-merge-failure.py b/unshred-binary-merge-failure.py
new file mode 100755
index 0000000..abb19c5
--- /dev/null
+++ b/unshred-binary-merge-failure.py
@@ -0,0 +1,81 @@
+#!/usr/bin/env python
+
+# Instagram Unshredder -- Binary Simplify Failure
+# by Jason A. Donenfeld <Jason@zx2c4.com>
+# for http://instagram-engineering.tumblr.com/post/12651721845/instagram-engineering-challenge-the-unshredder
+
+from PIL import Image
+from sys import argv, exit, stderr
+from math import sqrt
+
+if len(argv) < 4:
+	print >> stderr, "Usage: %s columns input output" % argv[0]
+	exit(-1)
+
+image = Image.open(argv[2])
+data = image.getdata()
+columns = int(argv[1])
+shred_width = image.size[0] / columns
+
+def pixel(x, y):
+	pixel = data[y * image.size[0] + x]
+	return pixel
+def pixel_distance(a, b):
+	opacity_a = a[3] / 255
+	opacity_b = b[3] / 255
+	a_r, a_g, a_b = (a[0] * opacity_a, a[1] * opacity_a, a[2] * opacity_a)
+	b_r, b_g, b_b = (b[0] * opacity_b, b[1] * opacity_b, b[2] * opacity_b)
+	return sqrt((a_r - b_r) ** 2 + (a_g - b_g) ** 2 + (a_b - b_b) ** 2)
+def match_score(left, right):
+	left = left[len(left) - 1]
+	right = right[0]
+	total = 0
+	for i in xrange(0, image.size[1]):
+		total += pixel_distance(pixel((left + 1) * shred_width - 1, i), pixel(right * shred_width, i))
+	return total
+def binary_simplify(order_lists):
+	simplified = list()
+	blacklist = list()
+	for i in order_lists:
+		if i in blacklist:
+			continue;
+		minimum = image.size[1] * 442 # = sqrt(3) * 255
+		value = None
+		right = False
+		for j in order_lists:
+			if i == j or j in blacklist:
+				continue
+			score = match_score(i, j)
+			if score < minimum:
+				minimum = score
+				value = j
+				right = True
+			score = match_score(j, i)
+			if score < minimum:
+				minimum = score
+				value = j
+				right = False
+		if value == None:
+			smushed = i[:]
+		elif right:
+			smushed = i[:]
+			smushed.extend(value)
+		else:
+			smushed = value[:]
+			smushed.extend(i)
+		simplified.append(smushed)
+		blacklist.append(i)
+		blacklist.append(value)
+	return simplified
+
+column_order = [[i] for i in xrange(0, columns)]
+print column_order
+while len(column_order) > 1:
+	column_order = binary_simplify(column_order)
+	print column_order
+column_order = column_order[0]
+	
+unshredded = Image.new("RGBA", image.size)
+for destination, source in enumerate(column_order):
+	unshredded.paste(image.crop((shred_width * source, 0, shred_width * source + shred_width, unshredded.size[1])), (destination * shred_width, 0))
+unshredded.save(argv[3])
-- 
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