Create decode.py

Oceanlotus/decode.py

@@ -0,0 +1,24 @@
+import png
+def get_rgba(w, h, pixels, x, y):
+“””Get RGBA pixel DWORD from x, y”””
+    pos = x + y * w
+    pixel = pixels[pos * 4 : (pos + 1) * 4]
+    return pixel[0], pixel[1], pixel[2], pixel[3]
+def decode_pixel(w, h, pixels, x, y):
+“””Get RGBA pixel DWORD at x, y and decode to BYTE”””
+    r, g, b, a = get_rgba(w, h, pixels, x, y)
+    return (r & 7 | 8 * (8 * b | g & 7)) & 0xff
+# Open payload image
+w, h, pixels, metadata = png.Reader(filename=”payload.png”).read_flat()
+size = 0
+x = 0
+y = 0
+# Decode size of payload
+while x < 4:
+    size = (size >> 8) | decode_pixel(w, h, pixels, x, y) << 24
+    x = x + 1
+print(hex(size))
+# Decode first row
+while x < w:
+    print(hex(decode_pixel(w, h, pixels, x, y)))
+    x = x + 1