Hacker News Reader

Comment by MauranKilom | Hacker News Reader

The part that makes higher error correction even more pointless is that errors can only be tolerated well in certain parts of the QR code. If the position markers are damaged, a scanner likely won't even recognize that there is a QR code visible, which obviates any error correction. The article mentions this in the very last sentence/caveat.

It feels a bit like the error correction exists mainly so you can embed fancy logos in your QR code... Avoiding damage to some parts but not others seems unaligned with real world scenarios...

View on HN

> It feels a bit like the error correction exists mainly so you can embed fancy logos in your QR code

Absolutely not the case. QR codes, like most 2D matrix codes were designed for logistics and supply chain, their leap into the consumer mobile phone arena was an interesting one, but not the original design intent at all (QR was developed at Denso, the automotive parts and logisitics arm of Toyota). The purpose for the error correction is so that the symbol can still be read on a label even if part of it is misprinted or obliterated, it works very well in practice. Industrial scanning software is mature technology, and more sophisticated than you imply (besides, segmenting and aligning barcodes, any barcode, in greyscale images is pretty simple). Position markers are easy to reconstruct and damage can be tolerated.

Since the position markers are constant they should be the easiest to recover if damaged. Considering how advanced computer vision is, a QR code can be identified without using them.

Agreed - QR recognition/alignment algorithms can clearly be improved further, and then when they are, higher error correction codes ought to be more reliable as designed.

It's not a case of can they be. It's a case of can they cheaply be.

The camera app on your smartphone likely searches for them by default. That means feeding at least 1-2 frames a second through it.

Basic pattern matching for the position markers is a rounding error overhead vs processing a video feed. Fancy computer vision is not - on lower end devices you may not have enough resources to do both and on higher end devices it'll still impact power usage.

Low tech stupid solution: carry a sharpie.

real CV programmers edit their QR codes with a sharpie

Approximately 10 years ago, I played with an Android app that takes the camera video input, looks for a Sudoku puzzle and then solves it. (AR Sudoku solver)

Detecting a QR code in real time should be possible on all devices by now...

Reply on news.ycombinator.com