diff --git a/Day 09/decode.py b/Day 09/decode.py
new file mode 100644
index 0000000..759ab34
--- /dev/null
+++ b/Day 09/decode.py	
@@ -0,0 +1,94 @@
+#!/usr/bin/python
+
+from PIL import Image
+import numpy
+
+im = Image.open("qr.png")
+input = im.load()
+
+# QR Version 4
+size = 33
+pixelSize = im.size[0] // size
+
+# rule 30
+codes = {
+    "111": 0,
+    "110": 0,
+    "101": 0,
+    "100": 1,
+    "011": 1,
+    "010": 1,
+    "001": 1,
+    "000": 0
+}
+
+
+def translatePos(pos):
+    x = pos[0] * pixelSize + pixelSize // 2
+    y = pos[1] * pixelSize + pixelSize // 2
+    return (x, y)
+
+def fillPixel(pos, bit, pix):
+    color = (0,0,0) if bit == 1 else (255,255,255)
+    for x in range(5):
+        for y in range(5):
+            pix[pos[0]*pixelSize+x,pos[1]*pixelSize+y] = color
+
+def readPos(pos, pix, size):
+    if pos[0] < 0 or pos[0] >= size[0] or pos[1] < 0 or pos[1] >= size[1]:
+        return 0
+
+    translated = translatePos(pos)
+    return 0 if pix[translated] == 255 else 1
+
+def readBufPos(pos, buf):
+    x = pos[0]
+    y = pos[1]
+
+    if x < 0 or x >= buf.shape[0] or y < 0 or y >= buf.shape[1]:
+        return 0
+
+    return int(buf[x,y])
+
+def rule30decode(x, y, buf):
+    bits = "".join([str(readBufPos(p, buf)) for p in [(x - 1, y - 1), (x, y - 1), (x + 1, y - 1)]])
+    return codes[bits]
+
+
+# Used to save rule30 pyramid for visualization
+def bufToImage(buf, filename, pixelSize = 5):
+    imgSize = (buf.shape[0] * pixelSize, buf.shape[1] * pixelSize)
+    outImage = Image.new('RGB', imgSize, 255)
+    outPixel = outImage.load()
+    for x in range(0, buf.shape[0]):
+        for y in range(0, buf.shape[1]):
+            color = (0,0,0) if int(buf[x,y]) == 1 else (255,255,255)
+            for i in range(pixelSize):
+                for j in range(pixelSize):
+                    outPixel[x*pixelSize+i,y*pixelSize+j] = color
+
+    outImage.save(filename)
+
+# 33 + 33/2 + 2
+bufSize = 51
+buf = numpy.zeros(shape=(bufSize,bufSize))
+buf[buf.shape[0]//2,0] = 1
+
+for y in range(1,buf.shape[1]):
+    for x in range(0,buf.shape[0]):
+        buf[x,y] = rule30decode(x,y,buf)
+
+# bufToImage(buf, "rule30.png")
+
+offsetX = (bufSize-33)//2-1
+offsetY = 0
+
+outImage = Image.new('RGB', im.size, 255)
+outPix = outImage.load()
+for x in range(size):
+    for y in range(size):
+        bit1 = readPos((x,y), input, im.size)
+        bit2 = int(buf[offsetX+x,offsetY+y])
+        bit = bit1 ^ bit2
+        fillPixel((x,y), bit, outPix)
+outImage.save("decoded.png")
diff --git a/Day 09/decoded.png b/Day 09/decoded.png
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index 0000000..75f699d
Binary files /dev/null and b/Day 09/decoded.png differ
diff --git a/Day 09/qr.png b/Day 09/qr.png
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index 0000000..eb1d5fe
Binary files /dev/null and b/Day 09/qr.png differ