Barcodes, MMS, and the Internet’s Cheapest Prices Greg McGrath & Greg Maier Advisors: Professor Cotter, Professor Rudko ECE-499 March 01, 2008

Afraid of Getting Screwed?

Project Goals Create a cell phone based system to compare prices by doing the following: Receive image from Locate automatically the barcode in image Decode the barcode Find best price online Respond to user with product information

30 Black Bars 29 White Space Each digit has unique 7-bit binary code Guard bars Barcode Standards

Barcode Location Algorithm Divide image into 8x8 blocks Take DCT of those blocks Compare each DCT block to average DCT block Find regions with a high sum, which implies a higher probability that the barcode is in that 8x8 region

Barcode Location Algorithm Cont. Threshold the image to remove low-value areas Convert remaining pixels to black and white Perform morphological operators to smooth barcode region

Barcode Location Algorithm Cont. Crop image to most relevant area Locate middle “guard bar” lines of barcode Find left and right edges of barcode

Decode and Read Barcode Find thickness of each black bar and white space in terms of pixels Repeat a number of times to minimize error Find mean each row scan Read left “guard bar” to indicate thickness of “one binary digit” Divide by pixel width by “one binary digit” to convert to binary form Convert from binary to UPC using standard table DigitPatternDigitPattern

Automate price comparison The UPC number is passed from MATLAB to Python Python opens q= PRODUCT &btnG=Search+Products&show=dd&scoring=p “Reads” HTML file to find price tags Saves lowest price (first item in list)

Connect with the consumer

Results and Performance 85% success rate Common source of error: 7-digit binary representation for each digit is slightly off

Problems Cell Phone Camera − Lack of user-determined focus Blurring Distortion

Cell Phone Camera

Digital Camera

Future Work Be able to send system the UPC directly Improve algorithm to work in more situations Allow the user to access more data about the product Average of the lowest five prices Name of the product Consumer Reports Recalls Improve error detection UPC Recognition Utilize error checking bit more effectively

Questions