最新刊期
期 3 ， 2014
- 摘要：Liquid crystalline compounds with difluoromethyleneoxy linkage group are widely used in liquid crystal mixtures.However,their phase behavior and physical properties have not been reported systematically.The mesomorphic properties of two series of compounds 1 and 2 with cyclohexyl group were thoroughly studied by using differential scanning calorimetry(DSC) and polarizing optical microscopy(POM).The effect of all the compounds on the mixtures were systematically investigated and their physical parameters were extropolated by using addition principle.The results show that compounds 1 have higher clearing point and wider nematic phase temperature range than that of compounds 2.Due to the increase of a fluorine atom on the skeleton,compounds 2 have higher dielectric anisotropy than that of compounds 1.Compounds 1 can significantly improve low temperature miscibility and broaden the mixed liquid crystal temperature range.关键词：liquid crystal mixture;mesomorphic property;dielectric anisotropy;miscibility
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发布时间：2020-08-12 - 摘要：From the perspective of the alignment materials, the relationship between alignment materials and image sticking has been studied thoroughly by using mini-cell as a platform.On the one hand, excellent stability of alignment film benefits Voltage Holding Residual (VHR); On the other hand, lower resistivity of alignment film is good for the release of residual current, which contributes to lower Residual of Direct Current (RDC).Good VHR and RDC play a key role in decreasing the level of image sticking.Therefore, mini-cell is a convenient way to evaluate the alignment materials, and the image sticking of TFT-LCD modules can be forecasted by analyzing the value of RDC and VHR.It provides guiding theory for bettering image sticking in production.关键词：alignment materials;voltage holding residual;residual of direct current;image sticking
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发布时间：2020-08-12 - 摘要：For the uptodate wide viewing angle technology, especially the IPS and FFS display mode, the usage of Pos liquid crystal is in the majority, because of the maturity of Pos liquid crystal craft and the ancillary material technology. Nevertheless, in accordance with the requirement of the LCD pro-ducts's optical capability enhancement, the study of the usage of Neg liquid crystal has been increa-sing, which is because of the relatively high transmittance, color shift improvement and display quality.In addition, Neg liquid crystal has many disadvantages, for example, relatively higher driving voltage and power consumption. Furthermore, the experiments have proven that the usage of Neg liquid crystal has serious image sticking problem. In consequence, Neg liquid crystal's stability and collocability with other materials remains have been improved. This paper compares the optical character and the display quality in FFS of Pos/Neg liquid crystal comprehensively by means of the Techwiz software simulation and samples' measurement data, elaborates the advantage and disadvantage of two kinds of liquid crystal and puts forward the suggestions where needs improvements.
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发布时间：2020-08-12 - 摘要：The device was prepared with the structure:ITO/MoO3 (40 nm)/NPB (40 nm)/TCTA (10 nm)/CBP: Ir (ppy)2 acac (x %)(30 nm)/BCP(10 nm)/Alq3(40 nm)/LiF(1 nm)/Al(100 nm).Ir (ppy)2 acac was the green phosphorescent dyes, x were 4%, 6%, 8% and 10% relatively.Luminous performances of the devices were studied by adjusting the doping concentration of green phosphorescent dyes. With 8% doping concentration and 490 cd/m2 luminance, the highest current efficiency of 69.43 cd/A was achieved, its maximal current efficiency was beyond 27.5% compared with 4% doping device .The reasons were as follows: firstly, the higher doping concentration means the higher opportunity of compounding of the carriers in the emitting layer; secondly, since CBP and Ir (ppy)2 acac were both 2.5 eV at LUMO energy level, electrons can directly transit from the main body CBP to the doping dye Ir (ppy)2 acac, avoid energy loss in the process of electron transmission into dye doping.High doping concentration has more advantage on the transmission of carriers, however, highly doping concentration would cause triplet exciton quenching. In addition, TCTA and BCP are carrier blocking materials, which had higher triplet energy, and thus excitons could be limited in the light-emitting layer.关键词：organic light-emitting diodes;phosphor;doping concentration;barrier layer
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发布时间：2020-08-12 - 摘要：Laser display has advantages of large color gamut, high degree of saturation,variable display screen size,no electromagnetic radiation etc.According to application requirements, a wide-angle laser projection lens using in dome-screen display system was researched and designed in this paper. White field and light power matching parameters of three primary colors of laser display were analyzed and calculated. Telecentric retrofocus structure was adopted. Spheric optical system of the projection lens was propitious to processing and testing. Distortion was controlled in design effectively. Aperture aberration was used to improve illumination of image edge of projection display and illumination uniformity. Focal length of system was 11.3 mm. The F number was 2.5.Full field of the lens can reach 110°.The MTF was greater than 0.6 at nyquist frequency in 90% field of view. Image illumination uniformity was better than 95%. Distortion was less than 1.5%. Chromatic aberration was less than 0.5 pixel. Analysis results showed that the design idea and method presented in this paper was feasible, and it was suitable for application requirements.关键词：laser display;colorimetry;dome screen projection;wide angle lens
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发布时间：2020-08-12 - 摘要：The effect of curing electric field waveform on the morphology of polymer network and the electro-optic properties of polymer-stabilized cholesteric texture (PSCT) was investigated. PSCT was prepared by means of polymerization induced phase separation (PIPS). By using three kinds of curing electric field waveform, the network morphology of PSCT can be controlled and the electro-optic properties of PSCT can be improved. When the curing electric field waveform is square, the polymer network is loosest, which results in the lowest threshold (saturation) voltage, longest response time, and largest hysteresis width. And the tightest polymer network can be observed with the triangle curing electric field waveform, which leads to the highest threshold (saturation) voltage, the shortest response time, and the smallest hysteresis width.关键词：polymer-stabilized cholesteric texture;electro-optic property;morphology of polymer network;curing electric field waveform
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发布时间：2020-08-12 - 摘要：In order to supply design rules for brightness viewing angle of liquid crystal display, this paper presents the detailed study of brightness viewing angle of side-type backlight unit. We consider that three reasons may have influence on the brightness viewing angle, which is type of light source entering light guide plate, type of light guide plate and collocation of optical film. First, short side entering type and long side entering type were studied; Second, different type of light guide plate, ink printed, injection and roll stamping light guide plate were studied; Last, different collocation of optical film were studied. Test data shows one half brightness viewing angle in horizontal direction of different entering type is about 50° under the same type of light guide plate and collocation of optical film, but short side entering type has different brightness distribution in horizontal direction. One half brightness viewing angle in horizontal direction of different light guide plate is about 50° under the same entering type and collocation of optical film, and brightness distribution in horizontal direction is almost same. The minimum value of one half brightness viewing angle is 27°, maximal value is 82° under the same entering type and light guide plate. Our study shows the main factor of brightness viewing angle is collocation of optical film, secondary factor is type of light source entering the light guide plate, and different type of light guide plate has no influence on brightness viewing angle.关键词：backlight unit;viewing angle;side-type;optical film;light guide plate
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发布时间：2020-08-12 - 摘要：Using 99.99% pure argon as sputtering gas, MgZnO films with wurtzite structure were prepared on quartz substrate by radio frequency magnetron sputtering technique with MgZnO targets of different Mg content and then annealed under 10-4 Pa in a tube furnace.Effects of Mg content on the optical properties of these films were studied. The results indicated that, with the Mg content increasing, the band gap increased and the near-bind-edge emission peaks occured blue shift in room photoluminescence spectra, and the intensity ratio between the ultraviolet near-edge emission and the visible deep energy level emission was reduced, which was accompanied by the decline in the quality of luminance lighting. Raman spectra of MgxZn1-xO agreed well with the wurtzite ZnO vibration modes, without any new bands arising from Mg substitution. The E2high Raman peaks were markedly broadened and the symmetry was altered upon Mg substitution. It indicated that the more compositional disorder defects were introduced in the MgxZn1-xO films with the increase of Mg content x,and the quality of crystal degraded.关键词：radio frequency magnetron sputtering;thin MgZnO films;Mg content;optical properties
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发布时间：2020-08-12 - 摘要：Silicon nitride thin films(SiNx) were deposited on the transparent conductive indium-tin-oxide (ITO)films by plasma enhanced chemical vapor deposition (PECVD),and was used in fabricating the fringe field switching thin film transistors.The defect of haze mura on the ITO films were studied.The obtained samples were characterized by scanning electron microscopy (SEM), Macro Scope/Micro Scope inspection system (M/M)and BLU Electro-optical Measure System.The result showed that the SiNx film surface plasma treatment played an important role in ITO transparence and film character, which can cause haze mura and undercut issue about dry etch process. The defect of haze mura can be improved by deposited thinner SiNx buffer layer and optimized surface plasma treatment.关键词：indium-tin-oxide;haze mura;FFS-TFT;PECVD;silicon nitride thin films;transmittance
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发布时间：2020-08-12 - 摘要：This paper presents a full-color LED display scheme based on simulation of PWM function. In this scheme, each LED is equipped with one D type flip-flop which is used to store information and control the LED on/off, and the LED status can be controlled by writing information into the D type flip-flop, thus the PWM function can be simulated and realized by writing the PWM binary code into the D type flip-flop cyclically and periodically. In the paper, the working principle of the system is introduced in detail, and the scan controller is designed carefully, and the parameters and feasibility of the system are also analyzed. Compared with traditional schemes, the proposed scheme has the advantages of lower power consumption and costs, as well as better functional flexibility; moreover, it eliminates the flickering and sacrificing brightness problem in traditional scanning scheme, and also has better signal and power integrity.关键词：LED display;PWM;embedded system;CPLD
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发布时间：2020-08-12
Table of contents
- 摘要：To save the use time of the IR camera in the Optic-Electronic tracking and measure equipment,the IR camera sequence construction system based on FPGA has been designed. The system can generate the simulated output signal of the IR camera, supplying the data source for the continuous image processing system when the equipment debug is done. In the system design, the FPGA programming and SignalTap tool was combined to measure the true sequence of the practical IR camera, and the detailed record file was generated. Based on the sequence file, the verilog language was used to program and the construction signal was output, which includes the clock signal CCDCLK, frame signal FVAL, row signal LVAL and data valid signal DVAL, the camera data CCDDATA was applied with the incremental number. In the experiment, the camera simulated signal was generated, the FVAL signal was 50 Hz, the CCDCLK signal was 40 MHz, and the image size was 640×512, the constructed data was supplied to the continuous system as the data source. The experiment proved that the constructed sequence signal was totally coherent with the practical IR camera, and the system ran well in the equipment debug period, the sequence constructed board could replace the camera when debugging. The IR camera sequence construction design makes the use time of the IR camera be saved, and item cost be economized. So the system design bears practical engineer meaning.关键词：IR camera;sequence construction;FPGA
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发布时间：2020-08-12 - 摘要：In order to solve the phenomenon of color temperature excursion for LCD at different luminance, the paper analyzes each part of adjusting white balance. First, according to the theory of adjusting white balance, the paper adopts the method of adjusting OGB backlight to realize white balance for LCD from extent of difficulty and accomplishment on each part. Then on the base of color sensor and FPGA as controller, software design and whole scheme design are presented. Finally, curve fitting and analysis are discussed.By analyzing and comparing test results, the effect of white balance will be perfect after experimentation of high and low temperature, vibration, wetness and mildew. After adjusting white balance,the range of color exhibition is enlarged and the color temperature can remain steady so that LCD can show image vividly. Besides, the range of color temperature is within ±0.005,the error is about 0.63%. LCD can meet the demand of color stability and color temperature on avionics display.关键词：FPGA;liquid crystal display;color temperature;white balance;backlight
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发布时间：2020-08-12 - 摘要：To the problem of large amount of high-definition video signal and the required transmission bandwidth, the embedded Gigabit Ethernet high-definition video transmission system is designed.The system selects Altera Cyclone II family FPGA chip as main controller, completing control of data acquisition, transfer and data processing control.System acquisition end selects the Camera Link interface, which data transfer rate up to 1 Gbit/s, and can provide a simple, flexible connection for high-definition camera.The data transmission mode selects Gigabit Ethernet technology, so that the video data can be transferred without any compression in high speed.The experiment uses a resolution of 1 392×1 040×8 bit, a frame rate of 16 Hz ultraviolet camera. The results show that the system can be transmitted to a maximum 52-frame image data per second, and the data flow velocity reaches 607.8 Mbit/s.The system has the characteristics of low cost, small size, low power consumption, stable performance, meeting most lossless video transmission system requirements.关键词：embedded system;gigabit ethernet;video transmission;FPGA
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发布时间：2020-08-12 - 摘要：An environmental adaptability display control system was designed for the wild harsh environment. The system is based on the design of the EL screen controlled by DSP and S1D13305. Both the interface circuit and software design methods between DSP and display control chip were discussed. The problem that the internal character content of the display control chip is single was solved. The initialization procedures of the system settings and display control chip settings were provided.The display driving module was developed. After the actual assessment and application, the display system in the wild harsh environment is stable, and has better display quality in actual use. The display system can achieve the desired effect.关键词：control;DSP;S1D13305;EL screen
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发布时间：2020-08-12 - 摘要：The paper proposes an improved Sobel adaptive edge detection algorithm for the sensitivity to noise and given threshold of the classical Sobel algorithm. First, the classical Sobel algorithm is improved and the direction of the detection is expanded. The adaptive threshold is automatically generated according to the background gray of the detecting pixel and the human visual property. Accordingly, the image edge that is more consistent with human subjective vision can be detected. The improved algorithm restrains effectively the noise by processing the edge image with mathematical morphologic method. The improved edge detection algorithm is embedded in a single FPGA and the system can collect image with high frame and resolution, detect edge and then display in real time taking advantage of high-speed parallel processing of FPGA.关键词：Sobel edge detection;adaptive threshold;human vision;mathematical morphologic;FPGA
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发布时间：2020-08-12 - 摘要：Organic light emitting diode (OLED) lighting module often has the problems of nonuniform distribution of luminance and color drift. In order to solve these problems, an improved control method of color temperature and luminance uniformity of OLED module is introduced in this paper, which is based on power management and luminance coefficient of RGB tricolor for white OLED lighting. Firstly, the power management changes the OLED module' working voltage,and then the OLED module's brightness is controlled coarsely. What's more, with the way of adjusting three primary colors RGB's coefficient, by changing the ratio and the size of the three primary colors R/G/B, it can realize the further fine tuning for the OLED module's brightness and its color temperature conti-nuously.The experiment result shows that the method can solve the OLED module's color temperature and brightness deviation due to the OLED color block's load, production process and other reasons, thus each OLED color block's brightness and color temperature deviation is reduced to range of 5 cd/m2 and 100 K. While it improves the uniformity of the OLED module's luminescence and realizes OLED light source illuminate at a large area.关键词：OLED module;color temperature;luminance;uniformity
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发布时间：2020-08-12 - 摘要：In order to solve the weak signal on the large size touch screen and design a large size infrared touch screen, a driving circuit design proposal is proposed which is suitable for this kind of touch screen, and it is well tested and analyzed systematically.In the circuit design, common small and medium size power tubes, such as transistors, Darlington transistors, MOSFET transistors are used to adjust circuit parameters to maximize the performance of the tube, then the transmit power of the circuit transient increases from the traditional hundreds of milliwatts to several thousands of milliwatts. Finally, based on the PIC32MX440F256H, the experimental design proposal was fully tested and the output results were compared with traditional driving circuit methods.The experimental results show that the maximum instantaneous current of infrared emission sensor driving circuit reaches up to 500 mA, and the instantaneous power is up to 2 500 mW, which is much larger than 125 mA of ordinary driving circuit. And the driving circuit of reception sensor can receive signal accurately from each emission sensor and output the corresponding electrical signal completely.The proposal can drive large-size infrared touch screen effectively, improve transient emission power, and reduce the overall power consumption, and also can improve the Signal to Noise Ratio (SNR).关键词：large size;multi-touch;infrared transmitter circuit;infrared receiver circuit
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发布时间：2020-08-12 - 摘要：To realize the need of low-cost intelligent access control/monitoring system,this paper designs the platform of the face recognition based on S3C2440 processor and researches the acquisition/display driver algorithms and face recognition algorithm based on the platform.Using Samsung's S3C2440 processor and OmniVision's OV9650 camera to build the hardware platform,the feature points of human face images is extracted by Harris algorithm, and the data in the database is matched to draw relevant information. In order to accelerate real-time facial image capture-matching the speed of the platform,the cache is opened to accelerate the program.The platform is designed using intelligent access control/monitoring systems to achieve the rapid identification of facial images,a simple structure and low cost.It meets the need of monitoring applications.关键词：S3C2440;face;identification
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发布时间：2020-08-12 - 摘要：In order to avoid rear-end collision,an embedded car ranging system based on the field-programmable gate array(FPGA) is presented and its applied algorithms such as image acquisition, image processing, monocular distance measurement based on small hole imaging and etc are investigated. The hardware platform for the design is Terasic DE2 FPGA development board. The system uses a single camera to measure the distance in real time between two cars. It acquires the CVBS (Composite Video Broadcast Signal) video stream from PAL camera. The system detects the range by image graying, filtering, detecting edge, dilation, erosion, locating license plate, computing the size and liquid crystal display. The whole system uses Verilog hardware description language to realize image acquisition and display, all kinds of image processing algorithm, license plate location and distance measurement algorithm. The image processing speed reaches 25 frame/s which greatly improves the real-time performance of the system. Experimental results indicate that the maximum distance error is only 2.57%. The system can be used for the auxiliary driving to prevent the collision or intelligent robot vision.关键词：FPGA;monocular ranging;DE2;CVBS;license plate location
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发布时间：2020-08-12 - 摘要：A new target recognition method for SAR images is proposed. An advanced denoising method named BM3D is introduced for the speckle noise suppression at the first time. BM3D filter combines advantages in space-domain denoising with those in transform-domain denoising, which leads to better performance. For the feature vector extraction step, Hu moments, which describe the target's cursory information, and Zernike moments, which describe target's fine information, are fused to construct the combination moments. In this way, the combination moments can express the target more comprehensively and precisely. In our experiment the moments are extracted from SAR images and used to train SVM classifier, and the experiment results indicate that the proposed method can obtain a recognition rate of 98.90%, which outperforms other SAR recognition methods.关键词：SAR image;target recognition;BM3D filtering;combination moments
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发布时间：2020-08-12 - 摘要：Nowadays, algorithm of unwrapping panoramic cylinder image is easy to produce the block effect, which reduces quality of expanded image greatly. According to the nature of the hyperboloidal mirror and the imaging principle,this paper analyzes the reasons for the defects of the existing algorithm, and gives a mathematical model based on the panoramic image cylinder radial scan unwrapping algorithm.The final algorithm is obtained combined with the unwrapping algorithm of radial scanning and the anisotropic interpolation algorithm. The experiments show that the new algorithm can effectively reduce the block effect and improve the quality of expanded image.关键词：anisotropic interpolation;panoramic images;radial expand
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发布时间：2020-08-12 - 摘要：In parallax autostereoscopic displays, the unreasonably designed device for generating parallaxes can result in moiré patterns, which influence 3D images. Thus, removing moiré patterns is a key problem in the parallax autostereoscopic displays. The paper introduces three principles for parallax autostereoscopic displays briefly. Two removing moiré patterns techniques in parallax autostereoscopic displays are demonstrated and reviewed: avoiding moiré patterns and moiré minimization. Moiré minimization technique is mainly introduced including engineering experiment, simulation of moiré patterns, approximate model of superposition of cosine gratings and technique of consistence between indicial equation method and Fourier theory. The latter two techniques provide detailed theoretical analysis and interpretation about moiré minimization in parallax autostereoscopic displays and supply design basis for other parallax autostereoscopic displays techniques.
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发布时间：2020-08-12 - 摘要：In order to overcome the shortcomings that weights of traditional non-local means are only decided by similar block's Euclidean distance and the influence of noise is not considered, a novel non-local means algorithm based on statistical property of similar block's pixels is proposed. This new algorithm first obtains the probability density function of similar block's Euclidean distance by employing the prior information of the Gaussian noise, and then formulates the probabilistic weights truly reflecting the similarity between two noisy patches. In the experiments, compared with traditional non-local means algorithm from the subjective and objective,this new algorithm gains 1 dB higher peak signal noise ratio than the traditional non-local means algorithm, and removes the noise more effectively while preserving significant image details.关键词：non-local means;probability density;euclidean distance;image denoising
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发布时间：2020-08-12 - 摘要：To fulfill the real-time processing requirement of computerized tomography image reconstruction, a FPGA-based accelerated CT image reconstruction method was proposed. Firstly, filtering projection algorithm was broken down by parallelism.Then the FPGA-based processing structure was proposed by using the parallel pipeline technology, and the designs of the main units of the method were discussed, including the designs of the filter, back-projection, and accumulation.Lastly, the system which includes 12 parallel processing pipelines was implemented on FPGA. The simulation results showed that,compared with the CPU reconstruction, the FPGA-based reconstruction achieved that reconstruction absolute error is less than 0.4% and the speedup ratio is more than 100, its speedup effect is more obvious when it is applied to larger amount of reconstructed image.关键词：FPGA;image reconstruction;parallel computing;acceleration
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发布时间：2020-08-12 - 摘要：The measurement matrix is one of the three core part of the compressed sensing theory, it influences the application of CS (Compressed Sensing) theory in the field of image fusion. In order to solve the problem that random measurement matrix is hard to realize for hardware, this paper designs a measurement matrix which is consisted only of minus one, zero and one, and then makes it no-related to sparse matrix as much as possible according to Gram matrix-based optimization method. The experimental results show that the proposed method can obtain higher PSNR gain of reconstructed image, and in the application of CS-based image fusion, our method can get a favorable fuse effect in the case of only 50% sampled.关键词：image fusion;compressed sensing;measurement matrix;gram matrix
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发布时间：2020-08-12 - 摘要：In order to achieve color image edge detection, the paper establishes color image automatic edge detection algorithm. The paper describes the color image representation based on the quaternion, achieves the color image edge detection algorithm based on snake operator. First, the paper describes color image edge detection according to the three primary of color images, the vector quaternion representation and quaternion basic computing methods. Second,the basic principles of snake operators and detection process are introduced. Finally, the paper constructs the dual quaternion operator and snake color image edge detection algorithm. The experimental results show that it can retain its original image information by using the color image edge detection algorithm and the edge information is intake. The color image representation based on the quaternion can basically satisfy stability and reliability, complete information, strong anti-interference ability and other requirements.关键词：Snake model;quaternion;color image edge detection;active contour
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发布时间：2020-08-12 - 摘要：Most methods based on level set do not have the stop criterion based on the global minimum, instead they employ the iteration number as stop criterion. This paper proposes an improved Chan-Vese model, by adding a constrained term, making the functional converge to global minimum, and presents the stop criterion based on global minimum, without setting iteration number in advance. Experimental results show that the proposed model can segment images correctly under the new stop criterion. Compared with the Chan-Vese model, it has a faster convergence, 3~6 times faster than Chan-Vese model, and is of good general use.关键词：image segmentation;Chan-Vese model;level set method
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发布时间：2020-08-12
- Address：No.3888 Dong Nanhu Road, Changchun, Jilin, China 130033 Postal code：130033
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