How do I use dmtxread to read a scanned data matrix?

I am trying to read a data matrix which I have generated from a private 2096-bit encrypted RSA key. The key was generated using gpg and printed to PDF with the following command: gpg --export-secret-key MY_PRIVATE_KEY_ID | paperkey --output-type raw | dmtxwrite -e 8 -f PDF > ~/key.pdf I then printed key.pdf and scanned it, producing the following jpg file: I now wanted to use the following command to recreate my private key: dmtxread /path/to/image.jpg | paperkey --pubring ~/.gnupg/pubring.gpg > my-regenerated-private-key.gpg However, the command dmtxread prints nothing to stdout and returns 1. I have tried tinkering with the error correction by using -C 10000, reducing the tolerance for rotation by using -q 5, and increasing the canvas size of the image to increase the number of blank pixels to the left and right of the matrix. I also tried with a larger resolution scan (I don't know the DPI, but it was 4MB and the squares were very well defined) and adjusting the contrast tolerance using -t 20 and -t 5, all with the same result (although I had to skip pixels using -S 5 with this large file to get it to finish in < 30 minutes). I tried using --verbose but nothing was printed to stdout (or any diagnostic file as far as I could tell). I have also tried the -D option to produce a diagnostic image. I'm not really sure what to make of the result though: Clearly it's struggling with some of the boundaries, but I'm not sure why or how to make dmtxread more robust. My next step was going to be attempting to decrypt a dummy file using the recovered private key, but obviously I didn't get that far. It's disappointing that this is so difficult; if there is no easy way to do this with the command-line libdmtx tools, maybe there is another tool that can do this for me out of the box? _Important_: it goes without saying that I would never use this private key for any actual encrypting, now that I've shared it online. You should never share your private key.