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So WTF is Maci Clare Peltz supposed to be? qartis
How to encode a message i a picture full#
Then it's 'i'.īy continuing in this way, we can decode the full message: Maci Clare Peltz. So far we've decoded "Ma".Ĭontinuing up and around the corner: 10100000 (masked), or 01100011 (unmasked). The next byte would be 10101101 (masked), which is 01100001 (unmasked). So the first byte would be 10000110 (masked), which is 01001101 (unmasked). We read the next 8 bits in a vertical zig-zag motion, like this: Since we're using 8-bit byte mode, our length field is 8 bits long. Here's the number of bits in the length field, for each encoding type: Like I said, the length field changes size depending on the encoding type. The next piece of information is the length field, or the number of characters (clusters of bits) that are in the message. So that means that our QR code uses 8-bit byte encoding. For our purposes these 3 encodings will be enough. They're used for encoding japanese characters, custom charsets and spreading a message across several QR codes in series.
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The other encoding types are rarely used in consumer QR codes. This means that our QR code's encoding type is 0100. However the bottom row is masked, so we invert the first two bits: 0100. So in our case, the tattoo itself has the bits 1000. The data areas are the yellow areas in this picture:
How to encode a message i a picture how to#
Note that we only mask the data pixels, and not the timing patterns or the format marker (otherwise we wouldn't know how to unmask it to get the mask reference number!). So in our case, we need to (in our mind, or using the pen and paper) invert all of the bits on odd-numbered rows. Once we've tiled the surface of our original QR code using the mask pattern, then every black pixel in the mask means we need to invert the corresponding bit in the original QR code. In our case we have a mask reference number 001, which means all of the odd-numbered rows are black. You can imagine the masking process as essentially covering the surface of the QR code in one of the patterns seen above, starting from the top left corner. The computer then unmasks the original data bytes using the same process, and retrieves the data.
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These undesirable features confuse the QR code reader, so the data is masked against a value in order to make the code easier to process when it's scanned by a QR code reader. The reason QR codes are masked in the first place is that sometimes particular combinations of data bytes produce QR codes with certain undesirable features (like big empty blocks in the middle).