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How printers and Photoshop detect and refuse to process images of currency

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Re: How printers and Photoshop detect and refuse to process images of currency

#61

Post by abrichr »

nappy-doo wrote: post #26
aaronem wrote: post #13

Earlier quoted context omitted.

Given that it was a decade and a half ago, and that even today's vending machine recognizers probably don't do much beyond making sure a few relatively gross features are present, I doubt the cost per counterfeit was all that close to $1.

You are absolutely, positively wrong on this front. The new bill detectors use PCA and SVM to analyze notes. They're so good the treasury department buys them because they're better than the best systems out there. Generally, however, the vending business is quite cheap. They buy the low end machine because there's not really a reason to bother buying the more expensive ones. However, go to a casino, or a foreign cou…

The new bill detectors use PCA and SVM to analyze notes.

What sort of features?

Re: How printers and Photoshop detect and refuse to process images of currency

#62

Post by t0mas88 »

sliverstorm wrote: post #56
wyager wrote: post #7

This is one of the things that made me really see the value of free software. I did verify experimentally that the Eurion constellation alone doesn't trigger photoshop's image rejection algorithm. I think it would be fun to distribute a bunch of images that false-positive the digimarc algorithms, just to mess with people.

This is one of the things that made me really see the value of free software. How do you mean? Is there much (legal) value to be had from image software that can process accurate scans of currency? I'm just kind of confused here, what value you speak of.

See below for example: "When I used to make news graphics for a tv station, every now and then this problem in Photoshop would arise and it was incredibly annoying to make anything with a flat dollar bill as part of the background."

Re: How printers and Photoshop detect and refuse to process images of currency

#63

Post by jjoonathan »

abrichr wrote: post #61
nappy-doo wrote: post #26

Earlier quoted context omitted.

You are absolutely, positively wrong on this front. The new bill detectors use PCA and SVM to analyze notes. They're so good the treasury department buys them because they're better than the best systems out there. Generally, however, the vending business is quite cheap. They buy the low end machine because there's not really a reason to bother buying the more expensive ones. However, go to a casino, or a foreign cou…

The new bill detectors use PCA and SVM to analyze notes. What sort of features?

You're right, that's the critical question. SVM on a picture of the note would be useless against all but the 12 year olds with paper and scissors. There's no reason to believe that the differentiating features from next years' printers would be separated by the same support vectors.

I think the real security is still in features that require expensive equipment to duplicate. Is it really that hard to use cheapo photodetectors to verify differential transmission/reflection (watermark), angle-dependent coloration (hologram), or to do some primitive spectroscopy (UV even) with a plastic lens and $10 CCD?

SVM might be a easy way to aggregate the features, but in that case it's just a calibration method and doesn't give any indication of the underlying security.

Re: How printers and Photoshop detect and refuse to process images of currency

#64

Post by StefanKarpinski »

nappy-doo wrote: post #26
aaronem wrote: post #13

Earlier quoted context omitted.

Given that it was a decade and a half ago, and that even today's vending machine recognizers probably don't do much beyond making sure a few relatively gross features are present, I doubt the cost per counterfeit was all that close to $1.

You are absolutely, positively wrong on this front. The new bill detectors use PCA and SVM to analyze notes. They're so good the treasury department buys them because they're better than the best systems out there. Generally, however, the vending business is quite cheap. They buy the low end machine because there's not really a reason to bother buying the more expensive ones. However, go to a casino, or a foreign cou…

That does seem like an ideal application for support vector machines. Do you know what kind of basis they use for SVM? Is it the usual exponential approach or something more specific to currency features?

Re: How printers and Photoshop detect and refuse to process images of currency

#65

Post by logicallee »

nappy-doo wrote: post #26
aaronem wrote: post #13

Earlier quoted context omitted.

Given that it was a decade and a half ago, and that even today's vending machine recognizers probably don't do much beyond making sure a few relatively gross features are present, I doubt the cost per counterfeit was all that close to $1.

You are absolutely, positively wrong on this front. The new bill detectors use PCA and SVM to analyze notes. They're so good the treasury department buys them because they're better than the best systems out there. Generally, however, the vending business is quite cheap. They buy the low end machine because there's not really a reason to bother buying the more expensive ones. However, go to a casino, or a foreign cou…

>They're so good the treasury department buys them because they're better than the best systems out there.

This phrasing is gold. "Our product is so good, the government buys it because it's better than the best thing out there." :)

Re: How printers and Photoshop detect and refuse to process images of currency

#66

Post by nappy-doo »

StefanKarpinski wrote: post #64
nappy-doo wrote: post #26

Earlier quoted context omitted.

You are absolutely, positively wrong on this front. The new bill detectors use PCA and SVM to analyze notes. They're so good the treasury department buys them because they're better than the best systems out there. Generally, however, the vending business is quite cheap. They buy the low end machine because there's not really a reason to bother buying the more expensive ones. However, go to a casino, or a foreign cou…

That does seem like an ideal application for support vector machines. Do you know what kind of basis they use for SVM? Is it the usual exponential approach or something more specific to currency features?

Yes, I know. No, I can't tell you.

Re: How printers and Photoshop detect and refuse to process images of currency

#67

Post by nappy-doo »

jjoonathan wrote: post #63
abrichr wrote: post #61

Earlier quoted context omitted.

The new bill detectors use PCA and SVM to analyze notes. What sort of features?

You're right, that's the critical question. SVM on a picture of the note would be useless against all but the 12 year olds with paper and scissors. There's no reason to believe that the differentiating features from next years' printers would be separated by the same support vectors. I think the real security is still in features that require expensive equipment to duplicate. Is it really that hard to use cheapo phot…

And this is where you're wrong. Most detectors use a PIN diode or a phototransistor. Both work just fine with the SVM.

Again, the security given in these detectors is SO good that even if I were to give you complete knowledge of the system, you can't beat them. I can't admit to having made counterfeits, but I can say that I've seen _all_ of them, and they do not work.

Re: How printers and Photoshop detect and refuse to process images of currency

#68

Post by aestra »

cheeseprocedure wrote: post #49

On a related note: many colour printers leave a tiny encoded pattern on each page (based on model/serial/etc), ostensibly to help track counterfeiters. [1] [2] Unfortunately, they're printed all the time. [1] https://www.eff.org/pages/list-printers-which-do-or-do-not-d... [2] https://www.eff.org/issues/printers

Perhaps also for forensics in case of other crimes as well.

Re: How printers and Photoshop detect and refuse to process images of currency

#69

Post by ChikkaChiChi »

What bothered me in the other thread where I first learned this is that while I have always understood that I don't have a reasonable expectation of privacy on the Internet, I feel dirty as shit when I realize my computer determines when something is legal or not for me to do.

Slippery slope, this one.

Re: How printers and Photoshop detect and refuse to process images of currency

#70

Post by nappy-doo »

jjoonathan wrote: post #63
abrichr wrote: post #61

Earlier quoted context omitted.

The new bill detectors use PCA and SVM to analyze notes. What sort of features?

You're right, that's the critical question. SVM on a picture of the note would be useless against all but the 12 year olds with paper and scissors. There's no reason to believe that the differentiating features from next years' printers would be separated by the same support vectors. I think the real security is still in features that require expensive equipment to duplicate. Is it really that hard to use cheapo phot…

Also, BTW, UV doesn't work on banknotes. If you wash a banknote with detergent, the paper absorbs the UV frequency bending stuff in modern detergents and corrupts the note. However, your thinking isn't far off.
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