Quality assurance of banknote printing plates is an important issue for the corporation which produces them. Every plate must be checked carefully and entirely before it's sent to the banknote printing factory. Previously the work is done by specific workers, usually with the help of powder and magnifiers, and often lasts for 3 to 4 hours for a 5*7 plate with the size of about 650*500 square millimeters. Now we have developed an automatic inspecting system to replace human work. The system mainly includes a stable platform, an electrical subsystem and an inspecting subsystem. A microscope held by the crossbeam can move around in the x-y-z space over the platform. A digital camera combined with the microscope captures gray digital images of the plate. The size of each digital image is 2672*4008, and each pixel corresponds to about 2.9*2.9 square microns area of the plate. The plate is inspected by each unit, and corresponding images are captured at the same relative position. Thousands of images are captured for one plate (for example, 4200 (120*5*7) for a 5*7 plate). The inspecting model images are generated from images of qualified plates, and then used to inspect indeterminate plates. The system costs about 64 minutes to inspect a plate, and identifies obvious defects.
KEYWORDS: Digital signal processing, Image processing, Field programmable gate arrays, Inspection, Signal processing, Image storage, Image transmission, Image sensors, Data conversion, Algorithm development
In high-speed banknote sorting system, to real-time deal with massive data and complex algorithm is required. This paper proposes an embedded processing system, which realizing the high-speed image acquisition and real-time processing of banknote image. The system is a customized and flexible architecture consisting of one large scale FPGA and four high performance DSP chips. The five processors have good communication with each other by RapidIO BUS. After evaluating the system-calculating overhead, the data throughput, and the hardware characteristics, we presents the whole processing program systematically running in FPGA and DSPs. In order to make full use of the advantage of FPGA highly parallelism and DSP deeply pipeline, the FPGA is designed for running parallel algorithms with large amount of calculation but low complexity of control flow, and the rest of algorithms are assigned to the four DSPs relatively. Finally, the whole program of image processing at the speed of 40 frames per second is realized on the embedded processing platform. The system has been successfully used in high-speed banknote sorting device, which has showed stable and reliable properties. And it also has excellent performance in processing ability with the verification of large scale operation.
A new sub-pixel interpolation algorithm based on multi-resolution filtering technology is presented in the paper. During the course of
the analyzing the algorithm, we theoretically testified the conclusion that the sub pixel imaging technology can improve system image
resolution. It can be concluded from the experiment result that the new interpolation algorithm can raise the resolution remarkably. We
presented a real-time system based on TI DSP to realize the new algorithm. The sub pixel imaging system is developed with the
flexible whole design and modular design so that it has the characteristics of extending, maintainability and easy soft developing.
In order to utilize the multiscale characteristics of wavelet transform more sufficiently, a new adaptive image restoration method using wavelet packets based on the edge detection is presented. The method allows for the decomposition of image signal with various frequencies in the subband domain. The proposed filters in the paper explicitly incorporate both within and between subband relations of the decomposed image. The adaptive filter is used in the approach for considering local adaptation in each subband of the best basis. In order to keep the high frequency information of the image, the adaptive edge detection is presented in the paper. Experimental results, which could test the proposed method, are got. It is found that the proposed method show not only great noise reduction in the processed images but also significant improvement of subjective image quality over the conventional image restoration methods.
KEYWORDS: Digital signal processing, Wavelets, Image restoration, Remote sensing, Electronic filtering, Image filtering, Digital filtering, Image processing, Data processing, Control systems
Considering the fact that the remote sensing image is mainly captured by a linear CCD with the push-broom way which the image varies over time, the time-varying wavelet packets for image restoration is proposed in the paper. On one hand, the result of the method is that the problem of the correlation between the images is solved, and on the other hand, it is the method that can remarkably reduce the calculating overhead and the data throughput, which is a key innovation for a real-time system. In this paper, the optimized wavelet packet bases by double tree searching algorithm are adaptively changed in different time. To realize the algorithm, we presented a dual DSPs real-time parallel system. The parallel system based on TMS320C6416-7E3 DSP has the characteristics of modular and flexible design and maintainability. The ping-pong structure and the streamline structure are both designed in the system. According to the complexity of the algorithm and the requirement of the data throughput, one of the two parallel structures can be realized freely only by changing a bit. It can realize the restoration algorithm with 4096*4096 images in real-time by demonstrated by our experiment in practice.
Regarding to big black speckle and cell like stripes in the IR images of a IR observation system introduced by the assembly precision, environment, the nonuniformity correction method and etc. after correction of the images for nonuniformity, an adaptive algorithm of nonuniformity correction based on neural network is introduced in this paper. And a real-time video signal processing system based on DSP and programmable devices is described in this paper in detail. Experimented with the IR observation system, the algorithm is able to despeckle images adaptively and the real-time realized in the hardware system proposed in this paper.
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