26-05-2012, 05:48 PM
BAR CODE RECOGNITION IN COMPLEX SCENES BY CAMERA PHONES
[attachment=23243]
INTRODUCTION
Modern mobile phones are high resolution colour displays, they support different standards of wireless networking, and they have reasonable processing power. Although still primarily used for voice communication, with the inclusion of digital cameras these devices have become a potential platform for machine vision application such as bar code recognition.
In recent years, advanced technology has succeeded in continuously producing smaller yet smarter devices.Now mobile phones can implement many new kinds of applications such as taking photos, and movie shooting by using embedded camera devices. So an interesting approach is capturing bar code with their cameras and decoding them withsoftware running on the phoneIn August 2006, 82.4 percent of the respondents whohad camera phones with QR Code (Quick Response Code) readers used camera phones with QR Code. But previous research work has shown that recognition of 2D barcode in mobile phone is very difficult because of the high noise, non-uniform illumination, skew distortion, low resolution and optical blur. It is very difficult to robustly extract accurate features such as edges and peaks of the bars and spaces from the barcode images taken by a camera phone.
BAR CODE
There are two types of barcodes are present -One dimensional and two dimensional. 1D barcodes have low data capacity, so we commonly use 2D bar codes. There ar two standardised 2D barcodes-Data matrix and quick response(QR) code.
DATA MATRIX
Data matrix is one of the most well known 2D bar code standards. It is widely used in the automotive, aerospace and computer manufacturing industries, for large data capacity labelling, such as direct part marking and package marking.
QR CODE
It comprised of the following patterns: finder pattern, timing pattern format information, alignment pattern, and data cell. The finder patterns located at the three corners of the symbol intended to assist in easy location of its position, size and inclination. Three dark-light-dark squers are overlapped in every finder pattern, and the dark- light ratio is 1:1:3:1:1. The timing patterns provide the secondary information which can help us to locate the symbol, decide the rotation direction of symbol and the width of module.The location of alignment pattern center is important for correcting the deformed shape.
Features of QR code
1) High capacity encoding of data
QR code has high capacity encoding of data, its maximum symbol can encode7089 numeric data or 4296 alphanumeric data.
2) High spead reading
Adapted with ccd reading, it can recognize more qr code symbol per second than pdf417 symbol for encoding same data capacity.
3) Chinese encoding capability
Chinese and Japanese characters are represented by a two byte compination in other two- dimensional barcode. But in QR code there is a specific chinese mode, it can use 13 bits encoding a chinese character.
[attachment=23243]
INTRODUCTION
Modern mobile phones are high resolution colour displays, they support different standards of wireless networking, and they have reasonable processing power. Although still primarily used for voice communication, with the inclusion of digital cameras these devices have become a potential platform for machine vision application such as bar code recognition.
In recent years, advanced technology has succeeded in continuously producing smaller yet smarter devices.Now mobile phones can implement many new kinds of applications such as taking photos, and movie shooting by using embedded camera devices. So an interesting approach is capturing bar code with their cameras and decoding them withsoftware running on the phoneIn August 2006, 82.4 percent of the respondents whohad camera phones with QR Code (Quick Response Code) readers used camera phones with QR Code. But previous research work has shown that recognition of 2D barcode in mobile phone is very difficult because of the high noise, non-uniform illumination, skew distortion, low resolution and optical blur. It is very difficult to robustly extract accurate features such as edges and peaks of the bars and spaces from the barcode images taken by a camera phone.
BAR CODE
There are two types of barcodes are present -One dimensional and two dimensional. 1D barcodes have low data capacity, so we commonly use 2D bar codes. There ar two standardised 2D barcodes-Data matrix and quick response(QR) code.
DATA MATRIX
Data matrix is one of the most well known 2D bar code standards. It is widely used in the automotive, aerospace and computer manufacturing industries, for large data capacity labelling, such as direct part marking and package marking.
QR CODE
It comprised of the following patterns: finder pattern, timing pattern format information, alignment pattern, and data cell. The finder patterns located at the three corners of the symbol intended to assist in easy location of its position, size and inclination. Three dark-light-dark squers are overlapped in every finder pattern, and the dark- light ratio is 1:1:3:1:1. The timing patterns provide the secondary information which can help us to locate the symbol, decide the rotation direction of symbol and the width of module.The location of alignment pattern center is important for correcting the deformed shape.
Features of QR code
1) High capacity encoding of data
QR code has high capacity encoding of data, its maximum symbol can encode7089 numeric data or 4296 alphanumeric data.
2) High spead reading
Adapted with ccd reading, it can recognize more qr code symbol per second than pdf417 symbol for encoding same data capacity.
3) Chinese encoding capability
Chinese and Japanese characters are represented by a two byte compination in other two- dimensional barcode. But in QR code there is a specific chinese mode, it can use 13 bits encoding a chinese character.