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This is actually "cameras can't focus close, and QR scanners aren't good at seeing a code which is tiny in the frame". By making the pixels of the code bigger,

This is actually "cameras can't focus close, and QR scanners aren't good at seeing a code which is tiny in the frame". By making the pixels of the code bigger, the camera can be a bit blurry to get the code big enough, and then it'll read.

deleted 3y ago
[deleted]
Retr0id 3y ago
I mean, that's kinda the whole point? The precise details of the optic path don't really matter, bigger pixels will always be easier to resolve. One might reasonably expect error correction to help with the decode of blurry inputs, but that wasn't really the case in my experiments.
- londons_explore 3y ago
  The 'proper' fix is to either engineer cameras that can focus closer, or to engineer barcode scanning apps to be able to see a code which is small somewhere in the frame. I think people are working on both as we speak.
  - deleted 3y ago
    [deleted]
  - Retr0id 3y ago
    It doesn't matter how objectively good your camera/decoder is, in absolute terms. There will always be some minimum size or maximum distance, where the detail can no longer be resolved (or errors no longer corrected)
    - subtra3t 3y ago
      Why? Is this something that's a side effect of some irrefutable physics law or a limitation of the current technology?
      - Retr0id 3y ago
        Both. You can't have a measurable feature smaller than the Planck length, but that's not relevant to QR decoding in any practical sense. As for the practical limits, try using your phone to take a picture of something very far away, or very tiny, and see what happens.
    - londons_explore 3y ago
      If we're talking theory, the pixel size doesn't matter - it's the amount of information encoded in the QR code that matters (ie. excluding ECC bits!). In turn, that means it is theoretically possible to decode a QR code where each 'pixel' of the code is smaller than the pixel of the camera sensor observing the code. While it is theoretically possible, nobody has yet done so...

deleted 3y ago

[deleted]

Retr0id 3y ago

I mean, that's kinda the whole point? The precise details of the optic path don't really matter, bigger pixels will always be easier to resolve. One might reasonably expect error correction to help with the decode of blurry inputs, but that wasn't really the case in my experiments.

londons_explore 3y ago
The 'proper' fix is to either engineer cameras that can focus closer, or to engineer barcode scanning apps to be able to see a code which is small somewhere in the frame. I think people are working on both as we speak.
- deleted 3y ago
  [deleted]
- Retr0id 3y ago
  It doesn't matter how objectively good your camera/decoder is, in absolute terms. There will always be some minimum size or maximum distance, where the detail can no longer be resolved (or errors no longer corrected)
  - subtra3t 3y ago
    Why? Is this something that's a side effect of some irrefutable physics law or a limitation of the current technology?
    - Retr0id 3y ago
      Both. You can't have a measurable feature smaller than the Planck length, but that's not relevant to QR decoding in any practical sense. As for the practical limits, try using your phone to take a picture of something very far away, or very tiny, and see what happens.
  - londons_explore 3y ago
    If we're talking theory, the pixel size doesn't matter - it's the amount of information encoded in the QR code that matters (ie. excluding ECC bits!). In turn, that means it is theoretically possible to decode a QR code where each 'pixel' of the code is smaller than the pixel of the camera sensor observing the code. While it is theoretically possible, nobody has yet done so...