When the iPod V4 (Touch) was released, the contrast resolution of the video system was good enough that it could be used for UPC and EAN bar code scanning. Sadly, with the release of the later versions of iOS 4, this changed and we found that it had it become impossible to scan any but the very largest codes.
One of our customers observed that it was possible to scan with the iPod when she used a magnifying glass, which set us to the task of evaluating iPod lenses and which got some surprising results.
We got a set of three lenses online in a set: a 180-degree fish-eye lens, a macro lens and a wide-angle lens:
They all use a magnetic mount ring that has to be permanently attached to the iPod by an adhesive backing. So we peeled off the cover paper and stuck one aroundd the camera aperture on the iPod.
If you buy these lenses, note that not all the adhesive mount rings are created equal -- some rings have a small cutout that allows them to be mounted on the iPhone 4 without obscuring the flash. This is not an issue with the iPod, which has no flash and the kit we got came with both kind of rings, but we notice that some of the lens kits offered on Google Shopping explicitly state that they are being shipped with mount rings that block the flash on the iPhone 4. So if you have both an iPod and an iPhone, and are planning on using the lenses on both, be careful what you buy!
Having mounted the ring on the iPod, the rest is simple. Each lens comes with a nice little plastic snap-on lens cover to protect it when not in use and a magnetic cover that snaps on the other side.
We removed the covers and, one by one, attached each lens to the iPod Touch by simply clicking it in place. The lens centers automatically on the ring, making placement simple:
We then did side-by-side scanning tests with an iPhone 4 using the following items:
- Digit-Eyes washable labels
- Digit-Eyes text labels
- Several CDs
- cereal box
- box of jello
- box baking chocolate
- saltine crackers
- bottle of Claritin pills
- small can of tuna fish
- small can of tomato sauce
- large can of stewed tomatoes
- can of mushroom soup
- can of dog food
- can of corn
- bag of flour
- our very favorite: the can of spam
What we found was this:
- without lenses, the capture rate for the iPod was zero; the capture rate for the 4 and 4s was 100%;
- the wide-angle lens and the macro lens did not improve the capture on the iPod at all. Not at any distance. Not for any type of code.
- The fish-eye lens did not improve the capture rate of the iPod on the Digit-Eyes audio and text labels (and other QR codes);
- The fish-eye lens VERY significantly improved the capture rate of the iPod on UPC / EAN codes. The scanning distance was between 4 and 6 inches, but the capture rate was close to 100%. The scan scan times were slower than the 4 /4S and we found it took some practice, but once we got the feel of it, it was fairly simple to capture the code. Once captured, the information was fully available.
A fish-eye lens is an ultra-wide angle lens that achieves an extremely wide angle of view by mapping the image into a convex appearance (wikipedia). The practical effect of using on on the iPod is that:
- the center area of the image of the code appears more clearly to the camera;
- the outside edges are distorted in both the horizontal and vertical dimensions;
- the recognition algorithms used in Digit-Eyes for UPC / EAN codes are tolerant of this because of the necessity of recognizing codes on curved surfaces (where the parallax makes the codes appear to the camera to "stretch"). The stretching of the code in the vertical dimension is immaterial when recognizing a UPC / EAN code.
- the recognition process for QR codes (which depend on accurate identification of the outside corner block codes) is not tolerant of this type of distortion and, as a result, the audio and text codes are unrecognizable.
The bottom line?
We much prefer the devices with the autofocus cameras and recommend using the iPhone 3Gs, 4, 4S or the iPad 3 for scanning if at all possible, but with the addition of these lenses, the iPod becomes usable for scanning.
It has been widely rumored that the next version of the iPod will have an autofocus camera and if this is true, the new iPod product will be a great device for scanning.
While waiting for the new product, if you already have an iPod and you really want to use it to recognize UPC / EAN codes, buying an inexpensive lens will definitely make it feasible to capture codes.
A word of caution, however! We got our lenses from a vendor in Hong Kong. Almost immediately after completing the purchase, the credit card number that we'd bought the lenses on was used to purchase airline tickets for someone located in Malaysia. We got a refund from the credit card company and no one got to use the tickets, but it was still a nuisence.
The lenses turned out to be available from a number of different vendors that we found on Google Shopping. Based on our experience, we'd recommend buying from a local vendor or one that you know.