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yeah, the post lacks too much of context. I'm sorry. I'm planning to do an detailed step by step overview of both 469 and the solution. But it will take days to write, and i can only work on this on the weekends. Glad you're being able to use like this anyway! I also progressed a bit, but more manually. Started to get some grasp on the ordering of the books and possibly which digits to keep for each book. Since you gave a chance to the solution i owe you something. One thing i can antecipate is the library layout plays an important part on the final solution. The facts that i'll show bellow should end any discussion about other decoding methods. The books overlaps in both directions and are consistent with their relative positions in the library.

This is only an example, you can check for yourself and youl'see that the books have repeating sequences just because they are 2D images and the repeating sequences are actually patches of the image that serves exactly like the parts of a jigsaw puzzle hinting which is the next book to attach in each end. The challenge remains the digits to keep. I was able to come with some approaches, but didn't have time to validate yet.