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Barcode by camera (reprise, sort of)

Hi,

I started designing this application (process an image; search for a barcode label in the field; decode) and have been trying to identify and address the various ways a user can "go wrong" in such an application (jitter, focus, orientation, etc.).

Apparently, QR codes are commonly "photographed" with cell phone cameras (recall, I don't use a cell phone so ignorance, here). But, I imagine this is a very "focused" activity -- hold camera steady, orient it properly (more or less), make the image as large as possible in the field, etc.

As always, I want to loosen the constraints on the user and still keep the software reliable, robust, etc.

First question: how "casually" can you image a QR label and get "reliable results" (power up camera/app, focus on QR label, snap picture, deal with consequences)?

For example, imagine a QR code label affixed to the door of an office. You are passing the office and -- almost as an afterthought -- realize that *this* is where the "Big Meeting" next week will be. Imaging the QR code will magically get and store this information for you. (in a Land of Make-Believe)

Can you just hold up your camera phone "in passing"?

Do you have to stop, deliberately focus the image, center it, zoom to fill the screen, ensure it is "level" with the edges of the viewfinder, verify the camera is "normal" to the label, snap and then *wait* (hope!) to verify that it was a good decode (lest you have to repeat the process)?

It's relatively easy to deal with scale and "skew" issues. But, what about cases where the label is on a "non-flat" surface (e.g., on a cylinder)?

Lastly, what's the typical (data) density of these labels? Do they "push the envelope" or just aim for "small and simple"?

Thx,

--don

Reply to
Don Y
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I'm no QR expert, but I think you may find this article on the topic interesting. It contains some of the technical specs and answers some of your questions.

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Ed

Reply to
Ed Beroset

There are many free QR readers available.

I have

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on my iPhone.

I can not "drive by" a large QR sign and get a fix on it.

If I stop and hold for only a second, I get the fix.

I have not tried any others.

hamilton

Reply to
hamilton

Excellent article, thanks! (making allowances for the "translation errors" :-/ Why is it that people -- apparently -- don't have a translation proofread by a "native speaker" prior to publication?)

Reply to
Don Y

Understood.

By "drive by" do you literally mean "in a motorized conveyance"? I.e., your speed would be "significant" -- though the distance to the target would be the defining factor, there.

Is this simply because you are moving (or preoccupied driving the vehicle?) and can't manage to get the camera "steady"?

If you are stopped for "only a second" (literally?), then I assume the application isn't sensitive to orientation problems? (Or, that you are good at intuitively orienting the camera to the target -- perhaps because the QR code is always presented to you in these situations in a *fixed* orientation? Imagine if the label was presented "tipped")

Reply to
Don Y

Recently, I read where a plane towed a large QR 'flag' near a beach in Germany (IIRC) and 'some' people were able to get it to read. many others evidently had to manipulate the image in some way. I suppose the novelty of it created enough curiosity to engage a serious commitment from people.

You should know Microsoft and perhaps others have codes in color and there is also at least one round-shaped code (I think it's on a beer lable?). Some of the codes are 'one-time' use and 'fixed', others can lead to 'sites' which allow for alteration in the future. Wikipedia has quite a bit of info.

There is also a type of RFID called, I think, a near-field device. It can be read by some PDAs/phones but is not visible. Posters of multiple images of products for instance can have a unique code which 'embedded' under each image, when 'interrogated' by a phone, the software would send your browser to additional info.

Reply to
1 Lucky Texan
[bits elided]

No doubt good for "publicity" but not very practical (if folks have to fidget with their phones to image it successfully)

Yes. (train) box cars (IIRC) have color coded labels as well. But color increases the complexity of decoding and printing.

I think fedex/ups (?) used a bullseye shaped code. Or, maybe it was for luggage tags?

I'm looking for more ubiquitous codes.

What they don't tell me is how easily these are used IN PRACTICE. E.g., if you have to spend a few seconds focused on "scanning" (imaging) the label, then it represents a significant interruption in work flow. Imagine, for example, groceries being marked with these labels and scanned with a camera phone! (of course a more specialized device would be built for that application. I make the point just to contrast my impression of their use vs. something

*like* "grocery checkout" in terms of their impact on the normal flow of your activities)

Yes, but they are more expensive to deploy (readers *and* tags). Labels are good because you can print them cheaply, *display* them (e.g., on a screen), etc.

Reply to
Don Y

I mentioned the various items I did because it isn't clear what you're attempring to accomplish.

Before RFID - type tech, freight cars were logged in/out of yards by guys with clipboards. If the number was obscured by mud or graffiti, or for human error type of reasons, inventory was lost/confused. Videomasters/SAIC installed a lot of systems to read the cars by radio interrogation. Perhaps there are other systems as well.

I think, at present, in terms of speed, convenience and accuracy, you should think of QR codes as lying on a spectrum between barcodes and typing in a URL.

Reply to
1 Lucky Texan

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