~charles/misc

71264ec6ef3707b305185d3c605dff97418b3774 — Charles A. Daniels 2 months ago bd815e1
add README
1 files changed, 9 insertions(+), 0 deletions(-)

A qtar2/README.md
A qtar2/README.md => qtar2/README.md +9 -0
@@ 0,0 1,9 @@
Example encode: `python3 qtar.py -o shuttle_768_5_4.pdf images/shuttle.jpg`

Example decode: `python3 quntar.py -i shuttle_768_5_4_scan.pdf -o outprefix`

Shell scripts are included that demonstrate adding redundancy using the par2 parity file creation tool, which can allow file contents to survive the loss of individual QR codes, or potentially entire pages with enough redundancy.

On my Brother DCP7065DN, the 82kb test image generates a 1.9MB PDF file 6 pages in length. Scanning it back in with the same device at 600DPI resulted in the entire file being successfully recovered. This results in a density of ~13kb/page, or about 615 pages per MB.

My motivational use case was to back up a ~1.5MB password database, which would be a bit impractical at this density. I think perhaps experimenting with the parameters a bit more may allow higher densities though, but I'm leaving that for future work for now.