Digital Cameras vs Scanners for OCR?

ttennebkram asks: "With 6 and 8 Megapixel cameras on the market, some now with Wifi built in, it might be more convenient to shoot pictures of your bills and papers with a camera than fussing with the scanner. By the numbers, it would seem feasible. 300dpi for an 8.5"x11" sheet of paper works out to about 8 megapixels; 300 dpi is usually what OCR vendors suggest. I imagine for high volume good results you'd want to maybe mount the camera on a tripod arm over your desk. Heck, I was thinking of a glass desk and maybe one camera below and one above, and maybe a foot pedal to trigger the cameras (and I suppose a flash and high F-stop would help as well). If I could quickly 'snap' all the junk paper I have and electronically file it, maybe OCR the images at night in batch while I'm asleep, and then maybe get rid of all that paper once and for all. Using a traditional cheap scanner just takes too long. So has anybody tried this? I realize that camera optics are different than scanner optics, so maybe it's not just a question of raw pixel counts. Any thoughts?"

Comments

I tried this once

[KNicolson]

The problems I had were (a) getting the book flat, and (b) getting the lighting right. With flash, you end up with a ring of brightness and by OCR software got very confused, as the grey newsprint outside the flash's ring was being handled as black.

If I were a whizz with Photoshop/GIMP/etc, I suppose I could have done some sort of correction to the picture, but...

I've heard how Kinko's have book scanners that will copy and bind a book for you - perhaps they also have a scanning to CD/DVD service? Would that be cheaper for you?

Re:Aspect Ratio and Even Lighting

[Null Nihils]

It's almost impossible to shoot a bill or a check stub dead on, at close rage, without fish-eye'ing, and without getting in your own shadow.

Thats assuming you need a pristine, perfect photo of the item to be OCR'ed. I suspect this is not the case: chances are that as long as you are trying to digitize printed (not handwritten) documents, the OCR won't mind a little fisheye distortion and offish lighting (as long as you make sure there is enough contrast and no dark shadows.) It really depends on the flexibility of your OCR software; it might not work well with the imperfections resulting from using a digital camera.

Best way would be to test out a few handfuls of documents, tweak your setup so you get the best resulting digital images, and then see how your OCR software handles things. I have used a digital camera to digitize things on paper when a scanner wasn't available, and sometimes got decent results for what I needed. Usually using the camera's flash is a mistake; instead, try setting up a flourescent tube so you get even ambient lighting. YMMV.

Re:Aspect Ratio and Even Lighting

[mrchaotica]

Now imagine that those receipts are notes and handouts from your college class, and that you'll want to search them later. Does it still sound like a "geek gone wild?"

reverse engineer this..

[RuBLed]

http://www.sentex.net/~mwandel/tech/scanner.html :)

Re:I sort of tried this

[flewp]

It sounds to me like he doesn't have the lighting under control at all.

Using a direct flash isn't exactly the best option. The ink, even though black, may pick up noticable, and troublesome highlights. Depending on the range, it may even lead to uneven lighting on the paper itself. (Having part of the paper brighter than the rest)

Ideally, perhaps you'd want to use softboxes or some other method for more diffuse lighting.

Disclaimer: I'm not really familiar with OCR software though, so I don't know how well it can compensate/overcome such lighting issues as I described.

Re:I sort of tried this

[flewp]

Forgot to mention that I often sketch on paper, and then bring my sketches into the computer for digital painting, and when using a direct flash, I've often encountered the problem I've described. I currently don't have a scanner, so when I am in need of bringing a sketch into the computer, I'm using a Digital Rebel XT (350D, for those outside North America/the United States)

Re:Aspect Ratio and Even Lighting

[tdemark]

I thought about keeping things electronically, but then I realize I'd have to take time to scan them and file them and that would take a lot more time, over all, than just dropping them in folders.

That's what I thought until I actually tried it.

I have an Fujitsu ScanSnap document scanner which I use on all my documents. It scans both sides of a page at the same time, can hold 15 pages (I think) in its feeder tray, and takes 5 or 6 seconds to scan a page. Since it scans both sides of a page at the same time, this actually ends up being 5 or 6 seconds per two pages.

It is small enough to sit on my desk and its "on" switch is the loading tray flap - flap closed is "off".

When I want to scan something, I open the flap, load the tray with the document, and hit the "scan" button.

It quickly scans all the pages and sends the scan to a program called Readiris Pro (v11) - this program will OCR the document and save it into my digital cabinet as a PDF "Image + Text". This is a really cool format because there are actually two "layers" to each page - the actual scan of the page (so it looks right) and then a text layer below that has all the OCR information. What this means is that, although you are looking at a raster image, you can search the PDF for specific information and copy and paste text right out of the document.

Let me clarify that with an example:

Let's say you have a PDF of a utility bill. The PDF you are looking at is a scan of the bill itself - not a text-based representation. However, you can grab the "text" cursor and copy your account number right from the image! Obviously, you are not copying from the image, but from the text layer that has all the OCR'd text positioned correctly on the page, but hidden from view.

Since all the text has been OCR'd, the PDFs are now searchable. Since my digital cabinet is just a collection of folders based on category (Utility, Financial, etc), I use another program (DEVONthink Personal) to index it. Let's say I am talking with my insurance company and they have a question about a claim. I can type in the claim number into DEVONthink and, boom, all the documents which reference that claim will be displayed. Simply clicking on an entry in the result list will bring up the document itself and highlight where the claim number appears on the page. BTW, if a provider allows PDF downloads of actual bills, I can drop them directly into the digital cabinet and they will be indexed along with my other documents.

Yes - this cost a little much to set up ($300 for the scanner (on sale), $90 total for DEVONthink and Readiris Pro), but I was able to sell the full copy of Adobe Acrobat that came with the scanner on eBay for $175, so the actual cost was closer to $225.

It's probably not for everybody, but I am certainly happy with the process.

- Tony

Re:Aspect Ratio and Even Lighting

[thatnerdguy]

How about just typing your notes up each day? That way you will be re-reading them, allowing them another chance to sink in, you'll be able to spot if there is anything in them that you don't understand and your notes will be searchable.

Re:Works for me

[iamhassi]

"A lot of people seem to be critisizing the idea, but there are some uses for it."

I agree. I don't know about the OCR thing but I take a picture of everything. Every business card I get, every little receipt or scrap of paper. And why not? Just takes a second and it's done, I always have a digital copy to go back and read or print out if need be.

If I only had a scanner I'd never bother, in fact I had a scanner for years before I had a digital camera capable of doing this and I never bothered then. It's saved my ass sometimes too, especially when the paper is filed away somewhere and it's easier to find the photo on the computer.