Understand QR error correction levels and why more correction is not always the best default.
QR codes include recovery information that can help a reader reconstruct data when part of the symbol is dirty or damaged. The standard options are commonly labeled L, M, Q, and H. DENSO WAVE describes approximate restoration capability of 7, 15, 25, and 30 percent respectively, although real scan performance also depends on where damage occurs and how the image is captured.
The capacity tradeoff
More recovery data leaves less room for the payload at a given version. A higher setting can therefore produce a denser code. Density may force a larger print size, and tiny modules can lose clarity on a low-resolution printer. Choosing H automatically does not guarantee the best real-world result.
Practical selection
For a clean digital display or protected paper, a low or medium setting may be adequate. Outdoor signs, tickets, industrial labels, or codes likely to be scratched may justify more protection. Decorative logos can also consume readable area, but error correction should not be treated as permission to cover arbitrary modules.
Test the actual artifact
Start with concise content, good contrast, and a clear quiet zone. Generate the code, print it at the final dimensions, and test clean and realistically handled samples. Try multiple phones and the dedicated scanner used in the workflow. The DENSO WAVE error correction overview provides primary background.