How would you like to design a bitcoin banknote?

[Serith]

Computers are color blind.

Try to read it with your smartphone, it should do it just fine.

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[teflone]

White..



Contrast is best..

[Sekioh]

Actually I'm pretty sure all your cameras on your phones take pictures in color

The base QR algorithm used in any decent apps have a threshold range yes, but that's usually like a RGB change of about 10, anything more than that and it's fine using colors, it uses filtering of light-vs-dark as binary, not specific color palettes. The WHOLE background area DOES need to match as solid, but it samples the 'background color' from the area around the location marks in the corners. The standards are a blank area outline surrounding the code and must be pseudo-solid color background. That example matches the required specifications fine.

For a light color like that it's fine. You don't even need to use black if I recall correct, just it's the most contrasted color

[unclemantis]

i tried doing a bitcoin banknote once upon a time

here's what i came up with ...



front and back

We sure have come a long way with the designs!

[cbeast]

I hate QR squares! You can't tell what they are. I suppose the QR barcode IP is all patented. It would be nice if Bitcoin had its own scannable thingamabob. We should make them all in florescent colors or something.

[casascius]

I believe the patent owner says the public may use it. It belongs to some Japanese company.

[bg002h]

I hate QR squares! You can't tell what they are. I suppose the QR barcode IP is all patented. It would be nice if Bitcoin had its own scannable thingamabob. We should make them all in florescent colors or something.

Give it a whirl...the right colors and it might work!

[Boussac]

We should make them all in florescent colors or something.

Yes one can make them look ok

[Vandroiy]

Mess with the QR code too much, and some device somewhere at some time won't be able to read it. "It works with my device" is not an argument a designer should use.

It's not that bad to prefer function over form.

[Matthew N. Wright]

It's not that bad to prefer function over form.

Use punchcards still do we? Form often drives technology.

[Raoul Duke]

Just leaving this here for whoever will work on the website as I think it will be handy.

http://raphaeljs.com/

[casascius]

I regularly scan QR codes with a handheld laser scanner. This scanner uses a red laser and likely a monochrome CCD sensor.

It is less tolerant of style and color but it is very fast and very tolerant of unusual scanning angles and poor ambient lighting conditions.

Tradeoffs like this favor the rapid scanning you would want to see in a retail setting.  It is the only way retail POS systems are ever going to practically accept bitcoins (besides digital ones sent via smartphone).  Favoring it and not assuming all QR codes will be targeting a color smartphone camera is a good idea.

[ErebusBat]

Mess with the QR code too much, and some device somewhere at some time won't be able to read it. "It works with my device" is not an argument a designer should use.

I rarely ever agree with Vandroiy; however he is 100% on this.  We are not trying to be Apple (are we?)  also keep in mind that these bills may be given to people who are like 'WTF is bitcoin?' but QR codes are becoming more and more widespread new (even on my potato chips and ketchup).  If you start changing that your average user may not connect it is a QR code and say 'OH gee thanks for this piece of paper, but i don't know what to do with it'

To specifically hit on the bolded part of the quote: There are reasons there are specifications and not just "hey make it kinda like this, test it on your smartphone, then you are good to go!"

[Stephen Gornick]

• Your modification should allow the user to choose from NON-DENOMINATED bills, or to enter a specific denomination of their choice.  This should be implemented by having the bill artwork itself not contain the denomination - rather, the resulting code should superimpose the denomination into the correct spot onto the bill.  An example of a way to make this work is to add something into .js that modifies the DOM that was begun by bitaddress.org to include an extra text input field where the denomination can be typed.

Right now a millibit is worth about a penny.  On a computer or mobile app, we see numbers in digital form and aren't uncomfortable seeing amounts like 0.1234 BTC.    On paper currency though, there are generally only whole numbers.  

Might it make sense, now that a millibit is worth about a U.S. penny, to start using millibit as the default denomination on these paper notes?

I could see handing out as a tip, accidentally, the one printed with "50 BTC" as the amount thinking it was the note printed with "50 mBTC" that I also happened to have in my wallet.

If the base unit for these was always millibits, this would be less likey to happen.   Or possibly instead always print at least three digits after the decimal separator?  e.g., even if it is 50 BTC, the amount printed would still be printed as 50.000 BTC?

[Update: Another reason to use whole numbers.  In locales where the comma is used as the decimal separator, 12.345 BTC would be printed 12,345 BTC.]

[World]

more inspiration
What a Bitcoin Looks Like
How would you like to design a bitcoin banknote?

[take5]

I could see handing out as a tip, accidentally, the one printed with "50 BTC" as the amount thinking it was the note printed with "50 mBTC" that I also happened to have in my wallet.

I think this is worth considering especially if bitcoin's value were to rise in the next year. I also liked the idea of printing the value in bitcoins and USD, EUR, etc. as it would make it seem more accessible to the average person and probably attract some interest.

[casascius]

I have pretty much assumed that bills would be printed in fractional bitcoins.  After all, it makes sense to walk around with notes of 0.1 - 1.0 BTC in your wallet, rather than 50!

Somehow, the prospect of people printing bills for amounts like 0.05 BTC is something I find to be EXCELLENT!  Reason being, people will find it weird, and then you explain to them that yep, in bitcoins there's no inflation, so printing bigger and bigger notes is not only unnecessary, it's silly, and that the notes will actually get smaller over time.  They're unzimbabwe notes!

[TTBit]

after printing one out..

I think a bit bill should be the size of a folded bill..

And have it so that folded one specific way in half.. should hide the private key..  

Like so..  think of this as each side of the bill


 ----------------
| X                X |
|                      |     - Front
 ----------------

 ----------------
| X                O |
|                      |      - Back
 ----------------


X's being the public addy, O being the private key..

Printing it like this, with a fold in the right direction can serve to hide the key until needed..  or even seal the bill shut with any tamper evident seal if made small enough you couldnt just look inside the folded bill..  

Have it like a Mad Magazine fold in, but front to back. 1/2 the private key is on the reverse, 1/2 on the obverse. Someone would need to copy both sides of the bill to steal. Could also rip in half.

[casascius]

I think double-sided bills are a very bad idea.  This is intended for novice users, who rarely own printers with duplexing abilities, and who aren't accustomed to making double-sided print jobs, and the risk that they will lose their money by printing the fronts and backs out of sync and finding out about it too late is far greater than the risk that someone will take an opportune picture of their bills and steal them.  It is a hazard to recommend this.

Private keys can be protected against the risk of casual photography if needed with nothing more than a post-it note.  Or by folding the bill in half.  (if folded outward, one code can be exposed while the other remains hidden).  Or by cutting out the bill from the sheet in such a way that there remains a foldable flap to cover the private key.

Also there is something to be said about which code is on the left and which code is on the right.  Imagine some cars had their brakes on the left and others had brakes on the right.  It would be a nightmare.  There is a reason why the location of pedals is kept consistent on cars, even for countries that drive on the non-standard side of the road, and that reason applies equally well to these notes.  For maximum compatibility and minimum confusion, the Bitcoin address should always be on the left, and the spend key should always be on the right, even on bills principally printed in a right-to-left language (Arabic, Hebrew, Farsi, etc.)

[2112]

I regularly scan QR codes with a handheld laser scanner. This scanner uses a red laser and likely a monochrome CCD sensor.

Please carefully read the documentation of your scanner. It may be possible to get the BER (Bit Error Rate) after the scan. Almost every scanner has it stored somewhere, but the ways to get it are different for each of them.

BER is the thing to watch for when really working with high-volume scanning.