I've done something similar back in university (a course about signal processing); we were reading some kind of 2d pattern which had alignment marks like a QR c

I've done something similar back in university (a course about signal processing); we were reading some kind of 2d pattern which had alignment marks like a QR code. There was also some (artificial) distortion done on the image so we had to handle that as well. IIRC the process goes something like this: Preparation: - Make your image grayscale - Clean up your pic somewhat (we did an Fourier analysis on the data to find any repeating distortion like a moiré pattern, plus some averaging of completely white or black pixels) - Adjust brightness so you have reasonable values throughout - Somewhere in there you reduce the size to 512x512 or similar to make your life a bit easier in terms of computing power. Finding the anchor points: - You create a "mask" of what you're looking for - You "move" that mask over your whole image, pixel-by-pixel - For each pixel position, you compute the difference between the image and your mask (this should give you a single value for each position) - The position with the lowest difference value is probably where your pattern is Our images were flat, but were rotated a random angle. Our alignment marks were circular, though, which makes the thing a bit a bit simpler. I imagine the actual QR code algorithm skews and rotates its "candidate" mask so it can find codes in a skewed image. Also, it might just make a first pass looking at big contrasting spots and seeing if they match what a finder pattern should look like. There's tons of ways this can be optimized to run fast on a limited device. Anyway, once you have the 3 finder "cubes", you can try and see if the alignment mark is where you expect it, and at this point I guess you have your QR position in the original image. What I'd probably do then is go back to the original image, extract the relevant portion of it and then rotate and skew it so it's "square" (there's a matrix transform you can use for this, IIRC). Then you can cut it up into "pixels" by following the timing marks, and the rest is explained in TFA.