• Title/Summary/Keyword: Robust adaptive algorithm

Search Result 376, Processing Time 0.024 seconds

Image Contrast Enhancement by Illumination Change Detection (조명 변화 감지에 의한 영상 콘트라스트 개선)

  • Odgerel, Bayanmunkh;Lee, Chang Hoon
    • Journal of the Korean Institute of Intelligent Systems
    • /
    • v.24 no.2
    • /
    • pp.155-160
    • /
    • 2014
  • There are many image processing based algorithms and applications that fail when illumination change occurs. Therefore, the illumination change has to be detected then the illumination change occurred images need to be enhanced in order to keep the appropriate algorithm processing in a reality. In this paper, a new method for detecting illumination changes efficiently in a real time by using local region information and fuzzy logic is introduced. The effective way for detecting illumination changes in lighting area and the edge of the area was selected to analyze the mean and variance of the histogram of each area and to reflect the changing trends on previous frame's mean and variance for each area of the histogram. The ways are used as an input. The changes of mean and variance make different patterns w hen illumination change occurs. Fuzzy rules were defined based on the patterns of the input for detecting illumination changes. Proposed method was tested with different dataset through the evaluation metrics; in particular, the specificity, recall and precision showed high rates. An automatic parameter selection method was proposed for contrast limited adaptive histogram equalization method by using entropy of image through adaptive neural fuzzy inference system. The results showed that the contrast of images could be enhanced. The proposed algorithm is robust to detect global illumination change, and it is also computationally efficient in real applications.

Disturbance Rejection and Attitude Control of the Unmanned Firing System of the Mobile Vehicle (이동형 차량용 무인사격시스템의 외란 제거 및 자세 제어)

  • Chang, Yu-Shin;Keh, Joong-Eup
    • Journal of the Institute of Electronics Engineers of Korea SC
    • /
    • v.44 no.3
    • /
    • pp.64-69
    • /
    • 2007
  • Motion control of the system is a position control of motor. Motion control of an uncertain robot system is considered as one of the most important and fundamental research directions in the robotics. Some distinguished works using linear control, adaptive control, robust control strategies based on computed torque methodology have been reported. However, it is generally recognized within the control community that these strategies suffer from the following problems : the exact robot dynamics are needed and hard to implement, the adaptive control cannot guarantee the performance during the transient period for adaptation under the variation, the robust control algorithms such as the sliding mode control need information on the bounds of the possible uncertainty and disturbance. And it produces a large control input as well. In this dissertation, a motion control for the unmanned intelligent robot system using disturbance observer is studied. This system is affected with an impact vibration disturbance. This paper describes a stable motion control of the system with the consideration of external disturbance. To obtain the stable motion independently against the external disturbance, the disturbance rejection is strongly required. To address the above issue, this paper presents a Disturbance OBserver(DOB) control algorithm. The validity of the suggested DOB robust control scheme is confirmed by several computer simulation results. And the experiments with a motor system is performed to give the validity of applicability in the industrial field. This results make the easier implementation of the controller possible in the field.

An adaptive digital watermark using the spatial masking (공간 마스킹을 이용한 적응적 디지털 워터 마크)

  • 김현태
    • Journal of the Korea Institute of Information Security & Cryptology
    • /
    • v.9 no.3
    • /
    • pp.39-52
    • /
    • 1999
  • In this paper we propose a new watermarking technique for copyright protection of images. The proposed technique is based on a spatial masking method with a spatial scale parameter. In general it becomes more robust against various attacks but with some degradations on the image quality as the amplitude of the watermark increases. On the other hand it becomes perceptually more invisible but more vulnerable to various attacks as the amplitude of the watermark decreases. Thus it is quite complex to decide the compromise between the robustness of watermark and its visibility. We note that watermarking using the spread spectrum is not robust enought. That is there may be some areas in the image that are tolerable to strong watermark signals. However large smooth areas may not be strong enough. Thus in order to enhance the invisibility of watermarked image for those areas the spatial masking characteristics of the HVS(Human Visual System) should be exploited. That is for texture regions the magnitude of the watermark can be large whereas for those smooth regions the magnitude of the watermark can be small. As a result the proposed watermarking algorithm is intend to satisfy both the robustness of watermark and the quality of the image. The experimental results show that the proposed algorithm is robust to image deformations(such as compression adding noise image scaling clipping and collusion attack).

A Study on the Improvement of Wavefront Sensing Accuracy for Shack-Hartmann Sensors (Shack-Hartmann 센서를 이용한 파면측정의 정확도 향상에 관한 연구)

  • Roh, Kyung-Wan;Uhm, Tae-Kyoung;Kim, Ji-Yeon;Park, Sang-Hoon;Youn, Sung-Kie;Lee, Jun-Ho
    • Korean Journal of Optics and Photonics
    • /
    • v.17 no.5
    • /
    • pp.383-390
    • /
    • 2006
  • The SharkHartmann wavefront sensors are the most popular devices to measure wavefront in the field of adaptive optics. The Shack-Hartmann sensors measure the centroids of spot irradiance distribution formed by each corresponding micro-lens. The centroids are linearly proportional to the local mean slopes of the wavefront defined within the corresponding sub-aperture. The wavefront is then reconstructed from the evaluated local mean slopes. The uncertainty of the Shack-Hartmann sensor is caused by various factors including the detector noise, the limited size of the detector, the magnitude and profile of spot irradiance distribution, etc. This paper investigates the noise propagation in two major centroid evaluation algorithms through computer simulation; 1st order moments of the irradiance algorithms i.e. center of gravity algorithm, and correlation algorithm. First, the center of gravity algorithm is shown to have relatively large dependence on the magnitudes of noises and the shape & size of irradiance sidelobes, whose effects are also shown to be minimized by optimal thresholding. Second, the correlation algorithm is shown to be robust over those effects, while its measurement accuracy is vulnerable to the size variation of the reference spot. The investigation is finally confirmed by experimental measurements of defocus wavefront aberrations using a Shack-Hartmann sensor using those two algorithms.

Real-Time Vehicle License Plate Recognition System Using Adaptive Heuristic Segmentation Algorithm (적응 휴리스틱 분할 알고리즘을 이용한 실시간 차량 번호판 인식 시스템)

  • Jin, Moon Yong;Park, Jong Bin;Lee, Dong Suk;Park, Dong Sun
    • KIPS Transactions on Software and Data Engineering
    • /
    • v.3 no.9
    • /
    • pp.361-368
    • /
    • 2014
  • The LPR(License plate recognition) system has been developed to efficient control for complex traffic environment and currently be used in many places. However, because of light, noise, background changes, environmental changes, damaged plate, it only works limited environment, so it is difficult to use in real-time. This paper presents a heuristic segmentation algorithm for robust to noise and illumination changes and introduce a real-time license plate recognition system using it. In first step, We detect the plate utilized Haar-like feature and Adaboost. This method is possible to rapid detection used integral image and cascade structure. Second step, we determine the type of license plate with adaptive histogram equalization, bilateral filtering for denoise and segment accurate character based on adaptive threshold, pixel projection and associated with the prior knowledge. The last step is character recognition that used histogram of oriented gradients (HOG) and multi-layer perceptron(MLP) for number recognition and support vector machine(SVM) for number and Korean character classifier respectively. The experimental results show license plate detection rate of 94.29%, license plate false alarm rate of 2.94%. In character segmentation method, character hit rate is 97.23% and character false alarm rate is 1.37%. And in character recognition, the average character recognition rate is 98.38%. Total average running time in our proposed method is 140ms. It is possible to be real-time system with efficiency and robustness.

An Adaptive Road ROI Determination Algorithm for Lane Detection (차선 인식을 위한 적응적 도로 관심영역 결정 알고리즘)

  • Lee, Chanho;Ding, Dajun
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.51 no.1
    • /
    • pp.116-125
    • /
    • 2014
  • Road conditions can provide important information for driving safety in driving assistance systems. The input images usually include unnecessary information and they need to be analyzed only in a region of interest (ROI) to reduce the amount of computation. In this paper, a vision-based road ROI determination algorithm is proposed to detect the road region using the positional information of a vanishing point and line segments. The line segments are detected using Canny's edge detection and Hough transform. The vanishing point is traced by a Kalman filter to reduce the false detection due to noises. The road ROI can be determined automatically and adaptively in every frame after initialization. The proposed method is implemented using C++ and the OpenCV library, and the road ROIs are obtained from various video images of black boxes. The results show that the proposed algorithm is robust.

Regularized Adaptive High-resolution Image Reconstruction Considering Inaccurate Subpixel Registration (부정확한 부화소 단위의 위치 추정 오류에 적응적인 정규화된 고해상도 영상 재구성 연구)

  • Lee, Eun-Sil;Byun, Min;Kang, Moon-Gi
    • Journal of Broadcast Engineering
    • /
    • v.8 no.1
    • /
    • pp.19-29
    • /
    • 2003
  • The demand for high-resolution images is gradually increasing, whereas many imaging systems yield aliased and undersampled images during image acquisition. In this paper, we propose a high-resolution image reconstruction algorithm considering inaccurate subpixel registration. A regularized Iterative reconstruction algorithm is adopted to overcome the ill-posedness problem resulting from inaccurate subpixel registration. In particular, we use multichannel image reconstruction algorithms suitable for application with multiframe environments. Since the registration error in each low-resolution has a different pattern, the regularization parameters are determined adaptively for each channel. We propose a methods for estimating the regularization parameter automatically. The preposed algorithm are robust against the registration error noise. and they do not require any prior information about the original image or the registration error process. Experimental results indicate that the proposed algorithms outperform conventional approaches in terms of both objective measurements and visual evaluation.

A Robust Watermarking Algorithm using Wavelet for Biometric Information (웨이블렛을 이용한 생체정보의 강인한 워터마킹 알고리즘)

  • Lee, Wook-Jae;Lee, Dae-Jong;Moon, Ki-Young;Chun, Myung-Geun
    • Journal of the Korean Institute of Intelligent Systems
    • /
    • v.17 no.5
    • /
    • pp.632-639
    • /
    • 2007
  • This paper presents a wavelet-based watermarking algorithm to securely hide biometric features such as face and fingerprint and effectively extract them with less distortion of the concealed data. To hide the biometric features, we proposed a determination method of insert location based on wavelet transform and adaptive weight method according to the image characteristics. The hidden features are effectively extracted by applying the inverse wavelet transform to the watermarked image. To show the effectiveness, we analyze the various performance such as PSNR and correlation of watermark features before and after applying watermarking. Also, we evaluate the effect of watermaking algorithm with respect to biometric system such as recognition rate. Recognition rate shows 98.67% for multimodal biometric systems consisted of face and fingerprint. From these, we confirm that the proposed method makes it possible to effectively hide and extract the biometric features without lowering recognition rate.

A Performance Comparison of DSE-MMA and QE-MMA Adaptive Equalization Algorithm in Nonconstant Modulus Signal (Nonconstant Modulus 신호에 대한 DSE-MMA와 QE-MMA 적응 등화 알고리즘의 성능 비교)

  • Lim, Seung-Gag;Ryoo, Si-Yeong
    • The Journal of the Institute of Internet, Broadcasting and Communication
    • /
    • v.21 no.2
    • /
    • pp.67-72
    • /
    • 2021
  • This paper compare the adative equalization performance of the DSE-MMA (Dithered Signed-Error MMA) and QE-MMA (Quantized-Error MMA) which has a simplifies the computational operation of currently used MMA algorithm. The DSE-MMA possible to improve the rubustness to noise by using the dithered signal consider the polarity of error signal in the multiplication part. In QE-MMA, it use the polarity of error signal after performing the nonlinear power-of-two quantizing operation for easiness of H/W implementation. The same channel environment was applied, and it's performance of the output signal constellation, the residual isi and maximum distortion and MSE that means the convergence characteristics, the SER that means the robustness of external noise of algorithm were compared and evaluated. As a result of computer simulation, the QE-MMA has more good in constellation, residual isi, maximum distortion, MSE performanc than DSE-MMA. In SER, the DSE-MMA has more robust due to dither signal than QE-MMA.

Robust Scheme of Segmenting Characters of License Plate on Irregular Illumination Condition (불규칙 조명 환경에 강인한 번호판 문자 분리 기법)

  • Kim, Byoung-Hyun;Han, Young-Joon;Hahn, Hern-Soo
    • Journal of the Korea Society of Computer and Information
    • /
    • v.14 no.11
    • /
    • pp.61-71
    • /
    • 2009
  • Vehicle license plate is the only way to check the registrated information of a vehicle. Many works have been devoted to the vision system of recognizing the license plate, which has been widely used to control an illegal parking. However, it is difficult to correctly segment characters on the license plate since an illumination is affected by a weather change and a neighboring obstacles. This paper proposes a robust method of segmenting the character of the license plate on irregular illumination condition. The proposed method enhance the contrast of license plate images using the Chi-Square probability density function. For segmenting characters on the license plate, binary images with the high quality are gained by applying the adaptive threshold. Preprocessing and labeling algorithm are used to eliminate noises existing during the whole segmentation process. Finally, profiling method is applied to segment characters on license plate from binary images.