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Image Processing, IET

Issue 4 • Date June 2011

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Displaying Results 1 - 8 of 8
  • Editorial: Research advances in computer graphics and multimedia security

    Page(s): 297 - 298
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (66 KB)  

    The rapid advances in computer graphics and multimedia security technologies have heralded a new age of explosive growth in multimedia applications such as real-time 3D game and secure multimedia content. The past decade has witnessed a proliferation of powerful multimedia systems and an increasing demand for practice of computer graphics and multimedia security (CGMS). CGMS has moved into the mainstream of multimedia and has become a key technology in determining future research and development activities in many academic and industrial branches. View full abstract»

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  • Simplification of point-sampled geometry with feature preservation

    Page(s): 299 - 305
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (514 KB)  

    A curvature-adaptive simplification method for point-sampled geometry (PSG) that efficiently preserves the surface features is presented. The main idea of the method consists of focusing on the edge intensities of sample points and the similarity of geometry features of sample points. Using the eigen analysis of normal voting tensor, with every point of PSG, an edge intensity is associated by which the PSG is decomposed into two components, one for the strong edge intensity and another for the non-strong edge intensity. Based on the adaptive mean-shift clustering, the second component is clustered into some clusters according to the geometric features' similarity. The first component and all these clusters are down-sampled, respectively, in combination with the mean-curvature threshold and sampling-density control to generate the simplified point set. In addition, the quality of the simplified PSG is evaluated using the error measurement method based on the moving least-squares surfaces. Experimental results show that the algorithm can achieve high-quality simplification result while efficiently preserving their features. View full abstract»

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  • Efficient block prediction-based coding of computer screen images with precise block classification

    Page(s): 306 - 314
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (730 KB)  

    This study presents a precise, one-pass block classification algorithm for efficient coding of computer screen images like power-point presentations, webpages and wall papers. The objective is to minimise the loss of visual quality of text during compression by separating text information which needs high spatial resolution than the pictures and background. It segments computer screen images into text/graphic, picture/background blocks by computing the statistical feature based on discrete wavelet transforms coefficients in the detail sub-bands of each 8×8 block, and then compresses the text/graphics pixels losslessly with a two-mode block prediction coding and the background pixels with the lossy JPEG algorithm. The proposed scheme performs accurate block classification of text information with different fonts, sizes and ways of arrangement from the background image, so that text/graphics blocks are compressed at higher quality than background image blocks. Experimental results show that the proposed method minimises block classification error and improves the value of peak signal-to-noise ratio significantly than standard JPEG, JPEG-2000 and H.264/AVC-I, while keeping competitive compression ratio and visually lossless quality of text information. View full abstract»

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  • Robust discrete wavelet-fan beam transforms-based colour image watermarking

    Page(s): 315 - 322
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (505 KB)  

    Combined discrete wavelet transform-fan beam transform (DWT-FBT) has been explored as a new possible domain for colour image watermarking. The two schemes proposed in the combined domain are (i) wavelet fan beam watermarking on luminance and chrominance and (ii) wavelet fan beam watermarking on chrominance alone. After the application of DWT on the host image and after careful selection of the suitable band of wavelet coefficients for applying FBT, watermarking is done by altering the fan beam transformed coefficients. The schemes proposed achieve a high data embedding capacity in addition to robustness to attacks and produce watermarked images of high quality. Results of the proposed schemes are compared with the two existing DWT-discrete cosine transform watermarking schemes to show its effectiveness. View full abstract»

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  • Gradient-based edge detection for motion estimation in H.264/AVC

    Page(s): 323 - 327
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    This study introduces a block-based motion estimation algorithm based on projection with adaptive window-size selection. Using one-dimensional (1D) projection, the original 2D block-matching problem is translated to a simpler 1D matching problem which eliminates the majority of potential pixel participation. The authors propose an efficient fast-motion estimation method using an intensity gradient algorithm to reduce the encoding time. The proposed algorithm estimates the texture direction of the block, and then a horizontal or vertical projection is employed for the sum of absolute difference calculation. Experimental results show that the proposed algorithm achieves a greater than 60% time reduction with negligible peak signal to noise ratio (PSNR) loss and BR increments. View full abstract»

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  • Rotation, scaling, and translation resilient watermarking for images

    Page(s): 328 - 340
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1234 KB)  

    Traditional watermarking schemes are sensitive to geometric distortions, in which synchronisation for recovering embedded information is a challenging task because of the disorder caused by rotation, scaling or translation (RST). The existing RST-resistant watermarking methods still have limitations with respect to robustness, capacity or fidelity. In this study, the authors address several major problems in RST-invariant watermarking. The first point is how to take advantage of the high RST resilience of scale-invariant feature transform (SIFT) features, which show good performance in terms of RST-resistant pattern recognition. Since many keypoint-based watermarking methods do not discuss cropping attacks, the second issue discussed in this study is how to resist cropping using a human visual system (HVS), which also helps us to eliminate computational complexity. The third issue is the investigation of an HVS-based watermarking strategy for extracting only feature points in the human attentive area. Lastly, a variable-length watermark synchronisation algorithm using dynamic programming is proposed. Experimental results show that the proposed algorithms are practical and show superior performance in comparison with many existing works in terms of watermark capacity, watermark transparency, and the resistance to RST attacks. View full abstract»

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  • Collision handling for free-form deformation embedded surface

    Page(s): 341 - 348
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (659 KB)  

    Recently, free-form deformation (FFD)-based simulation has received a lot of attention to achieve real-time animation of complex objects, and many researches have improved the accuracy of modelling complex material property. Previously, a free-form deformation axis aligned bounding box (FFD AABB) was proposed to approximate the FFD-embedded surfaces. Using FFD AABB, an efficient update of bounding box is achieved with balancing between accuracy and computational cost. The authors extended the FFD AABB with a more conservative collision handling method between FFD AABBs to deal with the cases that the nodes on one side of FFD AABB are out-of-plane. In addition, the authors adopted a broad-phase culling algorithm to cope efficiently with both self-collision and inter-collision using parallel spatial hashing. View full abstract»

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  • H.264 video watermarking with secret image sharing

    Page(s): 349 - 354
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (537 KB)  

    More people are studying digital video stream transference via networks. However, frequent Internet use increases the requirement for copyright protection and security. As a consequence, to prevent video streams that belong to rightful owners from being intentionally or unknowingly used by others, information protection is indispensable. The authors propose a novel method for video watermarking that is specifically designed for H.264 video. For the experiment, a low-energy signal can relatively guard against low-pass filter attacks. Conversely, a high-energy signal in the host signal can relatively guard against the high-frequency noise attack. In view of these facts, the proposed system design embedding algorithm provides high-energy and low-energy blocks. The blocks in the host image frame are divided into two different groups by estimating the block energy. The existing singular value decomposition methods were employed to calculate the watermark information. In order to enhance the security, the proposed system also employs torus automorphisms to encrypt the watermark. To achieve better robustness, the encrypted results use secret image sharing technology embedded into different I-frames in the video stream. View full abstract»

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Aims & Scope

The range of topics covered by IET Image Processing includes areas related to the generation, processing and communication of visual information.

Full Aims & Scope

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IET Research Journals
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