Understanding Barcode Encoding Barcodes are a great example of binary encoding. Barcodes are everywhere, on food items, on envelopes, on utility bills, on library cards. If you look at a typical UPC barcode (grocery item) you will observe a series of bars-30 bars to be exact. Each bar can be from 1 to 4 bits wide, the space between the bars can also be from 1 to 4 bits wide. Each bit represents a zero (white space) or a one (black line)- a triple wide line- 111 while a triple wide space-000. A single line, followed by a single space followed by a single line would be 101. You'lu notice that every UPC barcode begins and ends with the 101 pattern. Check a few UPC barcodes out. Pretty cool once you know what to look for. The binary digits are converted to their decimal equivalent (which is the human readable number you usually see printed beneath the barcode). If you are interested in interpreting the decimal encoding, look for the two five digit numbers. The five digit number on the left side is the manufacture code, while the second five digit number is the specific product code. All barcodes from the same manufacture will have the same five digit manufacture code on the left side (and of course the same binary bit pattern). Each unique product that a manufacture sells has a unique product or item number 716221 056817 Analyzing the above UPC barcode for Phippine Brand Mango Nectar you should be able to discern the 101 beginning and ending guard pattern that we discussed above. The Manufacture code is 16221 and the product code is 05681. The various width bars and spaces translate into the human readable digits you see below the barcode. The 7th digit at the end is a check-sum or error correcting digit. If you type the full 12 digit UPC number above into the Google search box, the first return link will be to a UPC database that identifies the product referenced by the UPC code. Try it with the number above, Type 716221056817 into Google and see what you get. Pretty Cool! Understanding Barcode Encoding Barcodes are a great example of binary encoding. Barcodes are everywhere, on food items, on envelopes, on utility bills, on library cards. If you look at a typical UPC barcode (grocery item) you will observe a series of bars-30 bars to be exact. Each bar can be from 1 to 4 bits wide, the space between the bars can also be from 1 to 4 bits wide. Each bit represents a zero (white space) or a one (black line)- a triple wide line- 111 while a triple wide space-000. A single line, followed by a single space followed by a single line would be 101. You'lu notice that every UPC barcode begins and ends with the 101 pattern. Check a few UPC barcodes out. Pretty cool once you know what to look for. The binary digits are converted to their decimal equivalent (which is the human readable number you usually see printed beneath the barcode). If you are interested in interpreting the decimal encoding, look for the two five digit numbers. The five digit number on the left side is the manufacture code, while the second five digit number is the specific product code. All barcodes from the same manufacture will have the same five digit manufacture code on the left side (and of course the same binary bit pattern). Each unique product that a manufacture sells has a unique product or item number 716221 056817 Analyzing the above UPC barcode for Phippine Brand Mango Nectar you should be able to discern the 101 beginning and ending guard pattern that we discussed above. The Manufacture code is 16221 and the product code is 05681. The various width bars and spaces translate into the human readable digits you see below the barcode. The 7th digit at the end is a check-sum or error correcting digit. If you type the full 12 digit UPC number above into the Google search box, the first return link will be to a UPC database that identifies the product referenced by the UPC code. Try it with the number above, Type 716221056817 into Google and see what you get. Pretty Cool
