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Reading QR codes without a computer

qr.blinry.org

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Re: Reading QR codes without a computer

#21

Post by londons_explore »

Retr0id wrote: post #18
londons_explore wrote: post #16

Earlier quoted context omitted.

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.

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.

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.

Re: Reading QR codes without a computer

#23

Post by bluGill »

yreg wrote: post #14

My friends often joke that a person who is checking our tickets is able to do precisely this mentally in their head – when that person is satisfied by seeing a QR code rather than scanning it. It became very popular over here with the Green Passes (EU Digital Covid Vaccination Certificates). Waiters, etc. were supposed to check whether the guests are vaccinated, but 99% of them just demanded any random QR code to be…

It would probably only take a week of training/practice for someone to get good enough to read them manually. Particularity if the vaccination codes have a common pattern - the same mask, format information and the like. I would expect you can look at a few areas to see if the person is vaccinated (though this wouldn't pick up on someone else's vaccinated status)

Re: Reading QR codes without a computer

#24

Post by efdee »

cyco130 wrote: post #5

Slightly off topic: One day in the late 90s or early 2000s, I wanted to transfer the contents of my Atari 8-bit disks to my PC. I did know about SIO2PC, a cable that converts between Atari's SIO port and the PC's serial port and a piece of software to go with it. But I didn't have the electronics skills to build one (even though it is actually very easy). So I ended up writing a Basic program on the Atari to read dat…

Just wanted to say this sounds like a fun project and you must have been pretty happy when it ended up working out!

Re: Reading QR codes without a computer

#25

Post by [deleted] »

londons_explore wrote: post #21
Retr0id wrote: post #18

Earlier quoted context omitted.

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.

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]

Re: Reading QR codes without a computer

#26

Post by Retr0id »

londons_explore wrote: post #21
Retr0id wrote: post #18

Earlier quoted context omitted.

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.

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.

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)

Re: Reading QR codes without a computer

#27

Post by mr_mitm »

bluGill wrote: post #23
yreg wrote: post #14

My friends often joke that a person who is checking our tickets is able to do precisely this mentally in their head – when that person is satisfied by seeing a QR code rather than scanning it. It became very popular over here with the Green Passes (EU Digital Covid Vaccination Certificates). Waiters, etc. were supposed to check whether the guests are vaccinated, but 99% of them just demanded any random QR code to be…

It would probably only take a week of training/practice for someone to get good enough to read them manually. Particularity if the vaccination codes have a common pattern - the same mask, format information and the like. I would expect you can look at a few areas to see if the person is vaccinated (though this wouldn't pick up on someone else's vaccinated status)

There is a digital signature embedded in the QR code. No one can verify that in their head.

Re: Reading QR codes without a computer

#28

Post by subtra3t »

Retr0id wrote: post #26
londons_explore wrote: post #21

Earlier quoted context omitted.

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.

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)

Why? Is this something that's a side effect of some irrefutable physics law or a limitation of the current technology?
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