iPhone Barcode Readers

[Kieren Diment]

On 01/03/2011, at 10:05 PM, Christopher Jones wrote:

> On 1 March 2011 09:49, Dave Cross <dave at dave.org.uk> wrote:
>> 
>> Need some advice on iPhone Barcode reading apps - so I turn to london.pm, my
>> favourite group of iGeeks.
>> 
>> My wife is a teacher and they're about to start a stocktake of all of the
>> books in the English department. Rather than count them all, she wondered if
>> there was an iPhone app that could help them.
> 
> 
> I'm fascinated to know how you could use an iPhone to scan a barcode - can someone explain?

With the camera ;)  Scanning high contrast images for information is a reasonably well solved problem.  Get rid of noise and highlight edges with a LoG (laplacian of gaussian filter - could be wrong here my knowledge is ancient and theoretical), then seeing as a barcode is basically a 2d image, use the barcode spec to get the information out of it by walking along the line measuring the thickness of the bars.