Design of ticket anti-counterfeiting detection system based on embedded technology

Tickets are tickets for watching the Olympics, concerts, and attending high-level conferences. With the development of high-quality image input and output devices, especially the emergence of color inkjet and laser printers with an accuracy of more than 1200dpi and high-precision color copiers, ticket counterfeiting has become easier. Therefore, people are in urgent need of an effective ticket anti-counterfeiting and detection technology. Traditional anti-counterfeiting technologies basically use material anti-counterfeiting, which belongs to common anti-counterfeiting. If counterfeited, the consequences will be disastrous, and there are also disadvantages such as high cost. Digital watermark technology belongs to personalized anti-counterfeiting technology. It is combined with individual characteristics, and does not change the mature printing process, printing materials and equipment, and does not increase printing costs. It is currently a better anti-counterfeiting technology.

1 Overview of Anti-Counterfeiting Detection System

1.1 Overview of Anti-Counterfeiting System

Watermarking is the operation of embedding information in a work without being perceived. Digital watermarking is to hide a mark (watermark) with specific meaning in digital products such as digital images, sounds, documents, books, and videos by digital embedding methods to prove the creator's ownership of his or her work. At the same time, the integrity and reliability of digital information are guaranteed through the detection and analysis of watermarks. Digital watermarking is an emerging and effective technology for copyright protection and data security maintenance of digital products. Using digital watermarking technology in the counterfeiting of printed products has been a new research direction in recent years.

The digital watermark ticket anti-counterfeiting system consists of two parts: the digital watermark embedding subsystem and the digital watermark identification subsystem. Each subsystem consists of two parts: hardware and software. Users can embed a digital watermark key that cannot be detected by the naked eye and does not affect the original visual perception of the protected printed matter in the printed matter of the ticket, and read the digital watermark through a unique detection device - a machine-readable device to identify the authenticity of the printed matter, thereby achieving the purpose of anti-counterfeiting.

This paper introduces the embedding of digital watermarks in tickets and describes the hardware and software in the watermark recognition system in detail. The hardware consists of a camera, ARM, LCD screen, etc.

The whole system process is shown in Figure 1.

1.2 Digital Watermark Embedding

As far as the current use of tickets is concerned, they are mainly printed (or printed) scanned (or photographed), so we need to find a digital watermark algorithm that is resistant to printing and scanning. Most of the algorithms that can be used for anti-counterfeiting of printed products are implemented in the transform domain, and their ideas are mostly based on the bracket frequency communication algorithm proposed by J.Coxdeng et al.

This paper will use the DCT (discrete cosine transform) algorithm to embed watermarks. Discrete cosine transform is one of the orthogonal transform image coding methods. For a typical image, after the transformation, most of the DCT energy in the image will be concentrated in the DC coefficient and the low-frequency AC coefficient. Many intermediate frequency and high frequency AC coefficients are close, and removing them will not significantly affect the quality of the reconstructed image. This paper embeds the watermark by performing DCT transformation on the ticket image, combining the visual characteristics of humans, and appropriately changing the value of a certain intermediate frequency coefficient. When extracting the watermark, you only need to judge the positive and negative of the corresponding intermediate frequency coefficient to restore the watermark image. Experiments show that the algorithm is simple and can effectively resist printing scanning.

The pictures before and after the watermark is embedded and the pictures with the embedded information are shown in Figures 2 to 4.

2 Watermark Detection System Design

The authenticity detection of tickets embedded with watermarks requires special machine-readable equipment. The equipment mainly consists of three parts: operating system customization, image acquisition, and image digital watermark detection. The core chip of the system uses the S3C2410 embedded microprocessor produced by SAMSUNG Semiconductor. The software environment uses the Microsoft Windows CE.NET operating system. The system first collects static images of tickets through a USB camera, then performs digital watermark detection and extraction, and determines the authenticity of the ticket by comparing the extracted digital watermark with the originally embedded watermark.

2.1 Customization of the operating system

An embedded system is a special-purpose computer system that is application-centric, based on computer technology, with customizable software and hardware, and adaptable to the strict requirements of specific application systems on functions, reliability, cost, size, power consumption, etc. Embedded systems have characteristics such as real-time performance, and their application prospects are very broad.

The system hardware platform uses the embedded development platform UP_NETARM2410_S of Broadcom Technology. The platform uses the S3C2410X microprocessor. The processor is developed using the ARM920T core, 0.18μm process CMOS standard macro cells and storage compiler. Its low power consumption and excellent full static design are particularly suitable for applications that are sensitive to cost and power consumption. The platform is also equipped with an LCD screen to facilitate the observation of watermark results.

Windows CE is an embedded operating system with preemptive multitasking and powerful communication capabilities. It is also a new operating system product designed by Microsoft for non-PC fields such as mobile devices, consumer electronics, and embedded applications. It has the characteristics of advanced modularity, good real-time performance, powerful communication capabilities, and support for multiple CPUs. Windows CE uses a user-friendly interface that looks very similar to the popular Windows NT interface, greatly reducing the difficulty of user use. At the same time, its modular design allows system developers and application developers to customize it for a variety of products. They can select, combine, and configure Windows CE modules and components to create a user version of the operating system.

Microsoft has launched an integrated development environment for Windows CE: Platform Builder and Visual Studio 2003. Through Platform Builder, developers can customize, build, download, debug and publish the Windows CE operating system. Visual Studio 2003 can be used to develop applications based on Windows CE.

Broadcom products come with Bootloader, BSP, SDK. First install Platform Builder and perform Windows CE porting. (For the specific porting process, refer to the product CD)

2.2 Image acquisition

This system uses the commonly used USB Vimicro camera on the market to collect ticket images. The USB driver is installed by default when Windows CE is installed. To enable the camera to collect data, you only need to write a stream interface driver for the camera.

The stream interface driver is designed for connecting to peripheral devices on the Windows CE.NET platform. In fact, the stream interface driver is a user-level dynamic link library (DLL) that manages peripheral devices. The stream interface driver can support almost any type of peripheral device connected to the Windows CE.NET system. To implement a stream driver, you need to complete the following steps:

(1) Select the file name prefix CAM that represents the device;

(2) Implement various entry points of the driver: CAM_Init, CAM_Close, etc.;

(3) Create a .DEF file;

(4) Create an entry for the driver in the registry;

(5) Generate stream driver zc030x.dll.

When the system automatically loads the driver, it must first copy the driver to the Windows folder. When the camera is connected to the hardware platform through the USB interface, it will prompt you to enter the camera driver. We type "zc030x" on the soft keyboard, and the camera will work normally.

2.3 Watermark Detection Software Design

The watermark detection software uses C# as the development language and is written based on the VisualStudio.NET (2003) integrated development environment (IDE). Visual Studio.NET and the .NET framework provide developers with a complete solution. Visual Studio.NET provides a development environment that can create applications based on the .NET framework. The development environment provides some tools that can simplify the creation, deployment and upgrade of applications. Since Windows CE.NET comes with .NET Compact Framework 1.0, applications generated in PC using VisualStudio 2003 can be directly downloaded to Windows CE.NET for use, making program deployment very convenient.

This system directly obtains image information through the USB camera. The software flow is shown in Figure 5.

3 Experimental Results Download Test Analysis

After designing the software in Visual Studio 2003 and successfully debugging it in the simulator, you can download the software to the experimental platform and run it. Install ActiveSync 4.1 before deploying the software, and select "Windows CE.NET, Device" when deploying the software (see Figure 6).

The running interface of the software on the WinCE system is shown in Figure 7.

4 Conclusion

Digital watermark printing anti-counterfeiting technology highlights the uniqueness and non-copyability of anti-counterfeiting, has high confidentiality and randomness, and does not change the visual image of the original printed matter, does not change the mature printing process, does not change the printing materials and equipment, and does not increase the printing cost. This article introduces a complete watermark embedding and detection system, which can be used in other fields with a little modification, such as document detection, packaging anti-counterfeiting, etc. This system still has some shortcomings, such as the watermark is extracted by the subjective judgment of the ticket inspector, and the embedded watermark cannot reflect the ID of the ticket well. These all need to be improved. However, the application of digital watermark detection technology to the field of printed matter will have a very broad application prospect.