Scanning QR Codes, do you find some wallets work better then others?

[DaveF]

Subject covers it.
Over the years I have had many issues scanning QR codes, but recently (say 4 years) it seems to have gotten better.

Now, it seems to be getting worse again for certain wallets.

I have a few wallets on my phone, I use different ones for different reasons. But at times, with the same QR code on the same screen one wallet will scan it with no problems and another will not unless I crank the brightness to 11 and get it at the perfect angle.

Just wondering if after a year it's time to buy my next phone or are there other people seeing this issue too?

-Dave

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[jackg]

Tldr: if it's brightness or "eye comfort" features causing the issue, I doubt they'll go by changing device. Check if your phone has an option to adjust brightness to a setting though - mine did without me knowing it would so I don't know if it's standard now or not.

I find it strange that a lot of exchanges crank up your brightness for you but wallet apps don't - it might be something to suggest to them as an improvement for the apps you use.

I normally assume it's the thing scanning the qr code that's the problem rather than the thing displaying it. If you're using a scanner that's meaning your phone is facing a screen then it's going to have glare issues from that - and that's not an issue with your phone unless your brightness is too low.

I'm kinda surprised nfc or other sharing tools aren't in higher demand than qr codes now - they're already quite an old technology imo. It's generally easier to scan a qr code on your phone and input something on a website than it is to try to get something to scan your phone.

[DaveF]

I find it strange that a lot of exchanges crank up your brightness for you but wallet apps don't - it might be something to suggest to them as an improvement for the apps you use.

I normally assume it's the thing scanning the qr code that's the problem rather than the thing displaying it. If you're using a scanner that's meaning your phone is facing a screen then it's going to have glare issues from that - and that's not an issue with your phone unless your brightness is too low.

I'm kinda surprised nfc or other sharing tools aren't in higher demand than qr codes now - they're already quite an old technology imo. It's generally easier to scan a qr code on your phone and input something on a website than it is to try to get something to scan your phone.

With NFC (or anything that can transmit) there is some form or greater risk according to some people. But, it's a hot wallet on a phone so there is that too.

What I just can't fathom the fact that when I wanted to pay someone for 1/2 of breakfast, blue wallet would not scan the QR, Zeus would not scan it, but Wallet Of Satoshi and poof done. But, at other times WoS won't scan but blue wallet will. And so on. Just trying to figure out if it's my phone, or if other people see it too. I can't see me be the only one. I know other people who only have 1 wallet on their phone have said that at times they can't scan some QR codes.

But was looking to see if anyone like me with multiple wallets find some work and some don't.

-Dave

[Hispo]

I have a 2019 smartphone with a camera of 12 MP.
I have used several wallets on it: Greenwallet, Schibald wallet, Trust wallet,  Blue Wallet and Samourai. I must way I have never had any trouble when scanning QR codes, the only think I can comment is the fact that sometimes it takes a couple of seconds to focus and read the QR code properly.

My personal appreciation is that those wallets worked just fine.

[joniboini]

I have more or less the same experience. Not only with crypto but with other apps too. I'm sure it is not because my phone camera is terrible. I tend to believe that QR code is buggy in general. Sometimes it works, sometimes it doesn't. I tried showing it on multiple monitors/displays but it is difficult to replicate the issue to the point that I use a QR scanner extension on my browser for work purposes.

[BlackHatCoiner]

I have a 5MP Aokin Rapsberry Pi camera; show me some respect. 

I don't have scanning issues, no. Not even once. Wallet software I use is Electrum and Sparrow for computer, and BlueWallet for mobile. The camera is used along with other hardware stuff, which consist Seed Signer.

I don't understand how are exchanges related to this. Do they mess up with QR codes?

[BitMaxz]

I only use two wallets for Bitcoin which are Electrum and Mycelium. They are both working fine unlike before when sometime scanning a QR code does not work right now if you have a better camera you can scan a QR code from any angle without any problem.

My current phone is an s9+ with 12mp I'm also using other finance apps for scanning QR codes and I don't have any problem yet.

My guess is you might be experiencing some issues due to outdated phone firmware most new software does not support the old android/ios version which I think is the reason why some BTC wallet QR codes do not work properly.

Or maybe you need to clean your camera a bit or reset the camera settings to factory default or just clear the data and cache under the application to fix your issue.

[DaveF]

I don't understand how are exchanges related to this. Do they mess up with QR codes?

Some places try to get 'cute' with a QR code:
Both of these point to 38s7D6x3hQP9uoYTEKJydwwxHnH7MgyRaq

The 1st one is the standard one we all know and love:


This is what (as an example) bitrefill gives you:


Close, but not great. Other places get worse with cute non standard QR codes. I was thinking that was the problem.


I'll see if I can get a picture of my friends phone, that I was trying to scan that started this thread, just after the bitrefill invoice I was trying to pay gave me grief. As I said some apps would flat out not scan it but WoS did in under a second.

Earlier in the week I was trying to pay a regular BTCPay invoice but no matter what I did my phone would not scan it on my daily use laptop. I took a screenshot and emailed it to myself and opened it on my home desktop and it worked. And my laptop screen is a newer and better then these ancient monitors I have here.

A couple of hours later I loaned someone here some BTC, he posted an address I copied it to mempool.space so I could get a QR code. And on that very same laptop with that very same phone that would not scan the other QR it worked. But, using a different app. Going back to blue wallet it would not scan. Went back to the 1st app and it worked. Tried to scan a different address in blue wallet and it worked??

So, we have 3 votes it's me / my phone. And 1 vote of yeah it happens to me too.
Lets see what others say.

The phone is a OnePlus Nord N10 5G about 15 months old. Not the best, not the worst.

-Dave

[nc50lc]

Both of these point to 38s7D6x3hQP9uoYTEKJydwwxHnH7MgyRaq

The former decoded into the address, purely the address string.
The latter has extra metadata, namely "bitcoin:", fee and rbf false flag; probably the cause of the issue in other wallets.

Electrum, Mycelium, Blockchain(dot)com, Bitcoin(dot)com and Blue wallets work.
Green on the other hand, scans, but has to manually delete the other data and leave the address.
(some of the tested wallets are outdated)

Maybe it has something to do with the QR Code's size, I'm viewing it with a 1080p - 22" monitor, 100% scale of the page.

[DaveF]

Both of these point to 38s7D6x3hQP9uoYTEKJydwwxHnH7MgyRaq

The former decoded into the address, purely the address string.
The latter has extra metadata, namely "bitcoin:", fee and rbf false flag; probably the cause of the issue in other wallets.

Electrum, Mycelium, Blockchain(dot)com, Bitcoin(dot)com and Blue wallets work.
Green on the other hand, scans, but has to manually delete the other data and leave the address.
(some of the tested wallets are outdated)

Maybe it has something to do with the QR Code's size, I'm viewing it with a 1080p - 22" monitor, 100% scale of the page.

Interesting, never thought about the metadata adding something the wallet does not like. Wondering now if it's a combination of things.
Extra data, not the best screen, not the best camera all causing it not to scan all the time. It needs that 'perfect viewing angle' kind of thing.
Have to do some more testing. Might be a good excuse to get a new phone too :-)

-Dave

[n0nce]

Great topic idea! I personally noticed (and experimented a bit) that multiple fast-switching QR codes are generally picked up better than fewer, higher density QR codes.
If a wallet works better, it's probably because it uses QR codes with fewer pixels. Even if you increase the on-screen size of a 'large' QR code, devices have a harder time recognizing it than a tiny, low-density code.

My theory is that it's partly due to scanning monitors instead of printed QR codes (as in a restaurant or on a wall). Not only do you usually have less light indoors; maybe try taking a picture of your PC screen with your phone and vice-versa to see how terrible they turn out. The shutter speed and screen refresh rate are out of sync, you could get glare based on the screen's surface finish and reflections from light sources. Add to that a potentially too bright backlight and you end up with a whole bunch of potential for issues.

The solution which works beautifully for me, is using 'smaller' QR codes. On both of my Passports, I always set the QR codes to the smallest size and PCs pick them up super fast, even in the worst conditions.
In its latest release, Sparrow added the ability to change the QR code size as well, which I found improved detection by Passport, too.

TL;DR: Photographing another screen can be challenging and the best solution is using multiple 'smaller' QR codes (less information per code).

[DaveF]

TL;DR: Photographing another screen can be challenging and the best solution is using multiple 'smaller' QR codes (less information per code).

I am also thinking that some screen protectors also cause issues. I peeled the one off my old pixel 4 and EVERY code scanned. Some took a bit of getting a good shot but in the end they all did scan.
Put on a new screen protector, and I could not read the bitrefill one or the bluewallet QR. Took it off and they all scanned. That was just with 1 wallet scanning. Will do more over the weekend. But I think the issue does come down a bunch of things:

1) Camera
2) Screen
3) Code itself

Some phones / cameras are probably more forgiving then others, and what looks fine to our eyes, or at least mine in terms of screens and screen protectors may be giving some cameras more stress then they can deal with.

-Dave

[n0nce]

2) Screen

The screen can have a variety (and in my opinion largest amount) of issues. Refresh rate, resolution, brightness, glare, dirt / fingerprints, panel type, viewing angles, and probably even more factors can change the difficulty for a camera to photograph it well.

Some phones / cameras are probably more forgiving then others, and what looks fine to our eyes, or at least mine in terms of screens and screen protectors may be giving some cameras more stress then they can deal with.

Exactly; the best way to test is to open a camera app on your phone or computer and point it at the other device's screen which you have issues scanning. I bet that the pictures won't turn out well.

There are even web articles about this (though in the context of getting people to learn doing actual screenshots and not in the context of QR codes on screens).

Digital cameras don’t work anything like the human eye; screens are completely different to pieces of paper. Although this might seem obvious in theory, it’s at the root of why cameras and screens don’t play nicely together.

In this example, they show how the 'screen photo' has curves and dots on it (moiré effect).
You also see how the brightness is not uniform from the bottom left to the top right corner, and in other circumstances it would probably also have some reflections.

Anyhow; QR codes are actually made for working in bad conditions like this; the artifacts in the picture should just not be too bad for the resolution / amount of data per code chosen by the creator.

[Pmalek]

<Snip>

I just tried scanning both codes from my Nokia 8 smartphone, which is already several years old. I made 8 scans altogether. 4 from my laptop screen and 4 from the connected external monitor. Both QR codes were scanned from both monitors using two different apps: Electrum and Google Authenticator. I know that Google Authy can't do anything with the codes, but that's not the point. I just wanted to test the scanning capabilities. I had no problems with any of the scans. I didn't even have to position the phone or keep the device steady. It had no problems capturing either code.   

[DaveF]

<Snip>

I just tried scanning both codes from my Nokia 8 smartphone, which is already several years old. I made 8 scans altogether. 4 from my laptop screen and 4 from the connected external monitor. Both QR codes were scanned from both monitors using two different apps: Electrum and Google Authenticator. I know that Google Authy can't do anything with the codes, but that's not the point. I just wanted to test the scanning capabilities. I had no problems with any of the scans. I didn't even have to position the phone or keep the device steady. It had no problems capturing either code.   

Having been playing with this a bit more since @n0nce posted a week or so ago I think it's more phone to phone.

I can get just about anything scanned on the PC screen. But scanning on phones is an issue. BUT, it's not just mine (OnePlus Nord N10) but iPhones and other.

I don't think it's the camera either. EVERY one that did not have a screen protector on worked. ALL the ones that had issues had some form of screen protector.

From the $2.99 for a 5 pack from Amazon to the $24.99 each super name brand. If one of the phones could not scan another phone that screen had some form of protector on it.

It's more of a when I have a few minutes and not a real scientific experiment.

-Dave

[Pmalek]

<Snip>

I tried to Google the issue, but except a few similar questions where people have reported the same things as you (having issues to scan QR codes on devices that had screen protectors), I didn't come across a source with a reasonable explanation. Scanning a QR code from a different phone isn't as common as scanning codes from other surfaces in order to make payments. One could assume that the error correction features that QR codes have, would be enough to make the codes readable even under a screen protection, but obviously that's not the case.

You could try to contact some of the companies that produce screen protectors and ask them for more information and feedback about the problems.
It would be interesting to see if the codes are scannable if only part of the screen is covered with a screen protector (a third or half of it). No one would use a screen protector in that way, obviously, but it's also an experiment to see how good the QR code error correction capabilities are.

[DaveF]

<Snip>

I tried to Google the issue, but except a few similar questions where people have reported the same things as you (having issues to scan QR codes on devices that had screen protectors), I didn't come across a source with a reasonable explanation. Scanning a QR code from a different phone isn't as common as scanning codes from other surfaces in order to make payments. One could assume that the error correction features that QR codes have, would be enough to make the codes readable even under a screen protection, but obviously that's not the case.

You could try to contact some of the companies that produce screen protectors and ask them for more information and feedback about the problems.
It would be interesting to see if the codes are scannable if only part of the screen is covered with a screen protector (a third or half of it). No one would use a screen protector in that way, obviously, but it's also an experiment to see how good the QR code error correction capabilities are.

I'm *guessing* it's 1/3 what n0nce talked about just taking pictures of screens does not always work perfectly, 1/3 screen protectors in general make it worse by adding a layer of distortion and 1/3 with phone makers trying to do all sorts of error correction and fancy tricks to make pictures look better is adding a bit of a difference to the picture coming into the app so it just sits there and goes 'duh'\

IMO this is going to get worse in the future as people are more likely to be sending funds using crypto apps on their phones to each other.

And, as lightning gets more use the amount of data in a QR is going to make it worse.



vs



-Dave

[n0nce]

From the $2.99 for a 5 pack from Amazon to the $24.99 each super name brand. If one of the phones could not scan another phone that screen had some form of protector on it.

That's very interesting. Completely clear screen protectors or with texture on them? And were they from glass (some thickness to it) or just thin plastic foil?
It's a fact that screen protectors affect the image quality of a smartphone screen, such as decreasing color accuracy and creating more fingerprints.

Did you notice that some phones were faster to scan a specific 'target' device than others? And do phones outperform a PC webcam?
Because I'm pretty sure that smartphones have ASIC or FPGA (depending on manufacturer) technology in the SoC for image recognition; amongst it, QR code recognition specifically.

Scanning a QR code from a different phone isn't as common as scanning codes from other surfaces in order to make payments.

Except if you're using QR codes as a communication medium between online device and airgapped hardware wallet.

And, as lightning gets more use the amount of data in a QR is going to make it worse.

The solution to this is using more QR codes with less data each (animated). I did some experiments about this and if a code is 'small' enough (in terms of data), it gets recognized immediately. So you can cycle through 4 codes and recognize them in 1-2 seconds instead of weirdly moving your phone across a single larger QR code with 4x the data amount.

[Pmalek]

Except if you're using QR codes as a communication medium between online device and airgapped hardware wallet.

Sure, but you can imagine how small that userbase is. We (as in all crypto users) are still quite a small part of the global financial economy. Then you have to take into account how many of those crypto users use crypto on a regular basis, which I consider at least once or twice a week, if not more. When you have gotten that far, it comes down to how many people own hardware wallets, and then an even smaller group who owns airgapped hardware wallets or airgapped computers. Lastly, how do those who use airgapped systems interact with their wallets. QR codes is one way of doing it. The other one is via USB drives. 

[DaveF]

That's very interesting. Completely clear screen protectors or with texture on them? And were they from glass (some thickness to it) or just thin plastic foil?
It's a fact that screen protectors affect the image quality of a smartphone screen, such as decreasing color accuracy and creating more fingerprints.

Clear, or if there was a tint it was so slight that I did not see / notice it. None with any kind of texture. But both the tempered glass and the older type plastic ones

Did you notice that some phones were faster to scan a specific 'target' device than others? And do phones outperform a PC webcam?
Because I'm pretty sure that smartphones have ASIC or FPGA (depending on manufacturer) technology in the SoC for image recognition; amongst it, QR code recognition specifically.

The newer iPhones worked best, the older which are only 2 or 3 gens out were uselessly bad. The androids were all average. Did not try with a webcam, just taking from a PC screen.

Scanning a QR code from a different phone isn't as common as scanning codes from other surfaces in order to make payments.

Except if you're using QR codes as a communication medium between online device and airgapped hardware wallet.

I think it really is for now such a niche things that until it starts to matter to the average user it really is going to just be what it is.
Might even start to change some marketing for places. i.e. our cameras are tweaked for qr scanning from other devices even though a screen protector.

-Dave