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Low-complexity and efficient image coder/decoder with quad-tree search model for embedded computing platforms

IET image processing 2018年第2期12卷 235-242页

作者： Ma, Tao Xidian Univ Sch Telecommun Engn Xian 71007 Shaanxi Peoples R China

Among the existing image coding methods, set partition in hierarchy tree (SPIHT) becomes a favourable choice for the energy-constrained embedded computing system because of its simplicity and high coding efficiency. In this study, the authors presented a quad-tree search model which is able to provide the higher coding efficiency than the model used in SPIHT. By applying this model, the authors proposed a new image codec, which is able to surpass SPIHT by 0.2-0.5dB in peak signal-to-noise ratio over various code rates, and its performance is even comparable to SPIHT with adaptive arithmetic code and JPEG2000. Also an experiment is conducted to show the complexity of the proposed codec is the same as SPIHT without the complicated arithmetic codes. This property is critically favoured in embedded processing communication systems where energy consumption and speed are priority concerns.

关键词： search problems quad-tree search model energy consumption Optimisation techniques code rates image coder computer vision and image processing techniques image and video coding arithmetic codes embedded processing communication systems image coding SPIHT image decoder quadtrees peak signal-to-noise ratio adaptive codes JPEG2000 adaptive arithmetic code set partition in hierarchy tree image coding methods decoding Codecs, coders and decoders energy-constrained embedded computing system codecs Combinatorial mathematics image codec

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Auto-encoder-based shared mid-level visual dictionary learning for scene classification using very high resolution remote sensing images

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IET computer vision 2015年第5期9卷 639-647页

作者： Cheng, Gong Zhou, Peicheng Han, Junwei Guo, Lei Han, Jungong Northwestern Polytech Univ Sch Automat Xian 710072 Peoples R China Civolut Technol Eindhoven Netherlands

Effective representation and classification of scenes using very high resolution (VHR) remote sensing images cover a wide range of applications. Although robust low-level image features have been proven to be effective for scene classification, they are not semantically meaningful and thus have difficulty to deal with challenging visual recognition tasks. In this study, the authors propose a new and effective auto-encoder-based method to learn a shared mid-level visual dictionary. This dictionary serves as a shared and universal basis to discover mid-level visual elements. On the one hand, the mid-level visual dictionary learnt using machine learning technique is more discriminative and contains rich semantic information, compared with the traditional low-level visual words. On the other hand, the mid-level visual dictionary is more robust to occlusions and image clutters. In the authors' scene-classification scheme, they use discriminative mid-level visual elements, rather than individual pixels or low-level image features, to represent images. This new image representation is able to capture much of the high-level meaning and contents of the image, facilitating challenging remote sensing image scene-classification tasks. Comprehensive evaluations on a challenging VHR remote sensing images data set and comparisons with state-of-the-art approaches demonstrate the effectiveness and superiority of their study.

关键词： image clutters rich semantic information remote sensing scene classification Geophysics computing scene-classification scheme auto-encoder-based method image recognition image resolution occlusions autoencoder-based shared midlevel visual dictionary learning VHR remote sensing images mid-level visual dictionary Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research image classification computer vision and image processing techniques geophysical image processing machine learning technique image representation very high resolution remote sensing images Atmospheric, ionospheric and magnetospheric techniques and equipment learning (artificial intelligence) mid-level visual elements Knowledge engineering techniques

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Predictive control of nonlinear visual servoing systems using image moments

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IET CONTROL THEORY AND APPLICATIONS 2012年第10期6卷 1486-1496页

作者： Copot, C. Lazar, C. Burlacu, A. Gheorghe Asachi Tech Univ Iasi Dept Automat Control & Appl Informat Iasi 700050 Romania

The visual servoing architectures with an eye-in-hand configuration, composed of a 6-d. o.f. manipulator robot and a video camera, are categorised as high-coupled and nonlinear systems. For this reason, in order to have a stable and convergent behaviour, advanced techniques like predictive control are needed. These types of techniques can solve the potential problems that can appear in classical (image-based visual servoing) while different type of constraints for visual servoing system can be fulfilled easier. Three different visual predictive control architectures based on image moments are proposed. The model for the image moments predictor used in the first architecture is an extension of a local model point features predictor. The second predictive approach uses an image moment-based predictor to describe the future behaviour of the system over a certain camera velocity scenario directly in the image moments space. In order to have a faster convergence and in the same time a desired behaviour of the servoing system, a reference trajectory is employed. This represents the main contribution of the last predictive control technique proposed in this study. A Matlab simulator was developed and all the visual servoing architectures described in the study were implemented. The simulation results showed that all the proposed visual predictive control approaches are stable and convergent when dealing with visual servoing tasks, but the best performances were assigned to the reference trajectory-based image moments architecture.

关键词： eye-in-hand configuration Spatial variables control visual servoing video camera trajectory control predictive control manipulators reference trajectory-based image moments architecture visual servoing architectures Matlab simulator 6-d.o.f. manipulator robot Nonlinear control systems visual predictive control architectures local model point features predictor nonlinear visual servoing systems nonlinear control systems Optical, image and video signal processing computer vision and image processing techniques feature extraction Optimal control image moments predictor image sensors camera velocity scenario Manipulators robot vision image-based visual servoing image sensors

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Estimation of edge displacement against brightness and camera-to-object distance

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IET image processing 2017年第8期11卷 568-577页

作者： Seo, Suyoung Kyungpook Natl Univ Dept Civil Engn Daehakro 80 Daegu South Korea

This study proposes a systematic method to estimate edge displacement (ED) from ground truth edges. To obtain ground truth edges and test edges, a series of target sheets containing the reference regions and brightness contrast regions were designed. Further, the brightness contrast regions were designed to contain foreground and background brightness between which the image edges occur. By varying the foreground brightness (FB), the influence of the FB on the edge locations was tested. Moreover, the influence of camera-to-object distance on the edge locations was tested. A simple least-squares method using slope profiles and a slope-based weighting scheme is proposed for calculating the edges occurring in contrast regions with subpixel accuracy. The experiment results revealed that a bright foreground moves the edge location towards the dark side of the edges in the range of 0-0.6 pixels with strong relationships between the FB and magnitude of ED.

关键词： least squares approximations image resolution slope profiles slope-based weighting scheme subpixel accuracy test edges foreground brightness brightness contrast regions least-squares method edge locations edge displacement computer vision and image processing techniques background brightness ground truth edges Interpolation and function approximation (numerical analysis) Optical, image and video signal processing camera-to-object distance

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General framework of the construction of biorthogonal wavelets based on Bernstein bases: theory analysis and application in image compression

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IET computer vision 2011年第1期5卷 50-67页

作者： Yang, X. Shi, Y. Yang, B. Beihang Univ Key Lab Math Informat & Behav Semant Minist Educ Sch Math & Syst Sci Beijing 100191 Peoples R China

The authors present a general framework of the construction of biorthogonal wavelets based on Bernstein bases along with theory analysis and application. The presented framework possesses the largest possible regularity, the required vanishing moments and the passband flatness of frequency response of filters. Based on this concept, the authors establish explicit formulas for filters of biorthogonal wavelets with arbitrary odd lengths. Meanwhile, a new family of parametric filters with symmetry is constructed. The choice of filter bank in wavelet compression is a critical issue that affects image quality. In this study, an optimal model of FIR aiming at image compression is brought forward, and the optimal finite impulse response (FIR) filters can be obtained correspondingly through sequential quadratic programming (SQP) and genetic algorithm (GA). The authors demonstrate the performance of the new family of filters given in this study for image compression with very encouraging results.

关键词： Optimisation techniques theory analysis image quality wavelet transforms biorthogonal wavelet construction genetic algorithm Bernstein base image and video coding Integral transforms band-pass filters genetic algorithms FIR filters passband flatness filter bank frequency response quadratic programming wavelet compression computer vision and image processing techniques Filtering methods in signal processing image coding sequential quadratic programming FIR filter filter frequency response image compression

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Second-order steganographic method based on adaptive reference matrix

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IET image processing 2015年第4期9卷 300-305页

作者： Yin, Zhao-Xia Chang, Chin-Chen Xu, Qin Luo, Bin Anhui Univ Minist Educ Key Lab Intelligent Comp & Signal Proc Hefei Peoples R China Feng Chia Univ Dept Informat Engn & Comp Sci Taichung Taiwan Asia Univ Dept Comp Sci & Informat Engn Taichung Taiwan

A second-order steganographic method (SOS) based on pixel pair matching and modification direction exploiting (MDE) is proposed in this study. In SOS, each cover pixel pair is used to conceal two secret digits in a B-ary notational system. Therefore the maximum embedding rate (ER) is up to log(2)B bit per pixel (bpp). It is different from the previous MDE-based methods in which only one secret digit in base B can be embedded into each cover pixel pair and the maximum ER is 1/2 log(2)B bpp. The experimental results demonstrate the improvements to the proposed method in terms of capacity, efficiency and detection rate compared to recent MDE-based methods. Take B = 3 as an example. The ER is 1.585 bpp and the corresponding average peak-signal-to-noise-rate is 49.89 dB, demonstrating the best image quality with the same embedding rate compared to recent MDE-based methods.

关键词： SOS method image matching peak-signal-to-noise-rate B-ary notational system visual communication Cryptography theory image recognition computer vision and image processing techniques modification direction exploiting MDE-based methods maximum embedding rate Cryptography image quality adaptive reference matrix second-order steganographic method steganography pixel pair matching

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Face recognition: challenges, achievements and future directions

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IET computer vision 2015年第4期9卷 614-626页

作者： Hassaballah, M. Aly, Saleh South Valley Univ Fac Sci Dept Math Qena 83523 Egypt Aswan Univ Fac Engn Dept Elect Engn Aswan Egypt

Face recognition has received significant attention because of its numerous applications in access control, law enforcement, security, surveillance, Internet communication and computer entertainment. Although significant progress has been made, the state-of-the-art face recognition systems yield satisfactory performance only under controlled scenarios and they degrade significantly when confronted with real-world scenarios. The real-world scenarios have unconstrained conditions such as illumination and pose variations, occlusion and expressions. Thus, there remain plenty of challenges and opportunities ahead. Latterly, some researchers have begun to examine face recognition under unconstrained conditions. Instead of providing a detailed experimental evaluation, which has been already presented in the referenced works, this study serves more as a guide for readers. Thus, the goal of this study is to discuss the significant challenges involved in the adaptation of existing face recognition algorithms to build successful systems that can be employed in the real world. Then, it discusses what has been achieved so far, focusing specifically on the most successful algorithms, and overviews the successes and failures of these algorithms to the subject. It also proposes several possible future directions for face recognition. Thus, it will be a good starting point for research projects on face recognition as useful techniques can be isolated and past errors can be avoided.

关键词： face recognition real-world scenarios face recognition systems computer vision and image processing techniques image recognition unconstrained conditions

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Robust image authentication scheme with self-repair capability for greyscale source document images via PNG format

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IET image processing 2016年第12期10卷 971-978页

作者： Wang, Feng Lyu, Wan-Li Pan, Jeng-Shyang Fujian Univ Technol Coll Math & Phys Fujian Prov Key Lab Big Data Min & Applicat Fuzhou 350118 Fujian Peoples R China Fujian Normal Univ Sch Math & Comp Sci Fujian Prov Key Lab Network Secur & Cryptol Fuzhou 350117 Fujian Peoples R China Anhui Univ Sch Comp Sci & Technol Minist Educ Key Lab Intelligent Comp & Signal Proc Hefei 230039 Peoples R China Fujian Univ Technol Coll Informat Sci & Engn Fujian Prov Key Lab Big Data Min & Applicat Fuzhou 350118 Fujian Peoples R China

Recently, Lee and Tsai proposed a new authentication method for greyscale document images using the portable network graphics format image;however, their method cannot resist the self-substitution attack, the same-position-substitution attack, or the cut-off attack. Furthermore, those attacks can be completed by the popular image editing software Adobe Photoshop. Therefore, the authors proposed a security-enhanced authentication scheme based on Lee and Tsai's method. The authors' proposed scheme uses three random binary sequences to randomise the binary version of a given greyscale document image, and thus overcomes the security flaws mentioned above. The authors' proposed scheme is capable of repairing the content of the given stego-image if attacked by the methods mentioned above. Moreover, the authors' proposed scheme retains all of the strengths of Lee and Tsai's scheme. The authors improve the opacity of the alpha channel of stego-image by using Wang and Su's extended secret sharing, and enhance the data security by using Hash functions. The experimental results show that the authors' proposed scheme is effective for application.

关键词： hash functions same-position-substitution attack self-repair capability PNG format image editing software computer vision and image processing techniques binary sequences document image processing portable network graphics format image greyscale source document images Document processing techniques steganography Data security random binary sequences cryptography random sequences stego-image security-enhanced authentication scheme Cryptography self-substitution attack cut-off attack Adobe Photoshop robust image authentication scheme Optical, image and video signal processing

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Bayesian image denoising using two complementary discontinuity measures

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IET image processing 2012年第7期6卷 932-942页

作者： Jung, C. Jiao, L. C. Gong, M. G. Xidian Univ Key Lab Intelligent Percept & Image Understanding Minist Educ China Xian 710071 Peoples R China

This study introduces a novel Bayesian image denoising method using two complementary discontinuity measures. The first discontinuity measure is the spatial-gradient, which has been widely used as a discontinuity measure. Although the spatial-gradient measure effectively preserves edge components in images, it is inadequate to detect significant discontinuities from noisy images because of its over-locality. Thus, the other discontinuity measure to detect contextual discontinuities for feature preservation is additionally required. The local-inhomogeneity measure provides the degree of uniformity in small regions, and is able to detect locations of the significant discontinuities effectively. Therefore the authors propose a Bayesian denoising framework using the two complementary discontinuity measures. The two complementary discontinuity measures are elaborately combined to be employed for creating prior probabilities of the Bayesian denoising framework. The experimental results show that the proposed method not only achieves a high peak signal to noise ratio (PSNR) gain from noisy images but also reduces noise effectively while preserving edge components.

关键词： two complementary discontinuity measures edge detection spatial-gradient complementary discontinuity edge components preservation image denoising contextual discontinuities Bayesian denoising framework peak signal to noise ratio noisy images computer vision and image processing techniques Bayesian image denoising method PSNR Optical, image and video signal processing

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New method for generating site-specific clutter map for land-based radar by using multimodal remote-sensing images and digital terrain data

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IET RADAR SONAR AND NAVIGATION 2011年第3期5卷 374-388页

作者： Kurekin, A. Radford, D. Lever, K. Marshall, D. Shark, L. -K. Plymouth Marine Lab Plymouth PL1 3DH Devon England Gen Dynam UK Oakdale NP12 4AA Blackwood Wales Cardiff Univ Commun Res Ctr Cardiff CF24 0YF S Glam Wales Cardiff Univ Dept Comp Sci Cardiff CF24 3AA S Glam Wales Univ Cent Lancashire ADSIP Res Ctr Preston PR1 2HE Lancs England

By using multimodal remote-sensing images and digital terrain data of the environment, this study presents a new method for generating the clutter map specific to the selected land radar site and the radar's operating parameters. In the proposed method, the estimation of backscattering from the environment involves extrapolation of the airborne radar remote-sensing image to provide the baseline values, classification of multispectral remote-sensing satellite images to provide a detailed description of terrain types, use of digital terrain elevation data with the land radar position and height to provide local grazing angles and a terrain visibility map and use of the digital topographic map to provide the geometric reference for all data sets. Using actual remote-sensing images and digital terrain data acquired from a real environment with various terrain features, the clutter map generated by the proposed method for land-based radar is compared with that generated by the competitive modelling method. The accuracy of the proposed method is demonstrated based on the differences with respect to the actual clutter measurements using a different airborne radar-sensing configuration.

关键词： computer vision and image processing techniques Geophysical techniques and equipment Geography and cartography computing comprehensive modelling method site-specific clutter map Instrumentation and techniques for geophysical, hydrospheric and lower atmosphere research radar imaging local grazing angles backscattering estimation multimodal remote-sensing images Optical, image and video signal processing digital topographic map terrain mapping Radar equipment, systems and applications multispectral remote-sensing satellite image classification clutter measurements remote sensing by radar terrain visibility map backscatter land radar position land-based radar radar clutter digital terrain data airborne radar

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