H. Sun and W. Kwok, "Concealment of damaged block transform coded image using projections onto convex sets," IEEE Trans. Image Processing, vol. 4, no. 4, pp. 470--477, Apr. 1995.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... waveform coding, i.e. redundancy in the waveform coding stage [6] 5) Robust entropy coding, which places redundancy in the entropy coding stage [11, 13] 6) Postprocessing at the decoder, which blindly recover the lost pixels based on their surrounding spatial or temporal neighborhood pixels [3, 15]. In [20] Yin et al. show that the quality of blind recovery can be enhanced by embedding additional features in the image. For instance, they embed the edge directionality information bit of blocks into images. In this paper, we propose a new method of using our ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. on Image Processing, Vol. 4, pp. 470-477, Apr. 1995.

.... concealment may fail in the presence of scene changes, fast motion, rotation and deformation of objects [2] Therefore, a practical algorithm should also include a spatial interpolator to recover missing macroblocks (MB) e.g. based on a DCT domain formulation [3] or on projection onto convex sets [4]. Spatio temporal techniques have also been proposed, using boundary matching [2] or Markov random fields (MRF) 5, 6, 7] In most spatio temporal error concealment algorithms, once a corrupted MB or slice has been detected, one has to decide whether to apply spatial or temporal restoration. For ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Transactions on Image Processing, vol. 4, no. 4, pp. 470--477, Apr. 1995. (c) (b) (d) Fig. 6. An inter-coded frame from the foreman sequence: (a) original; reconstruction using (b) F-MS, (c) MB-MS, (d) GBM-MS

....spatial error concealment is an invaluable resource. As for spatial error concealment, several techniques have been proposed. The problem has been formulated in the DCT domain [2] where smoothness of the recovered MB can be easily imposed. Projection onto convex sets has also been suggested [3]. More recent approaches consider edge preserving interpolators. Amongst others, in [4] it is proposed to estimate edge directions by means of the Hough transform while in [5] an approach based on sketch theory is taken on, consisting in the recovery of contours followed by bilinear interpolation ....

H. Sun, W. Kwok, "Concealment of damaged block transform coded images using projection onto convex sets", IEEE Transactions on Image Processing, vol. 4, no. 4, pp. 470-477, Apr. 1995.

.... domain, but also to the spectral domain such as the discrete cosinetransform (DCT)domain, as proposedby Chung et al. 16] Some other methods are based on projection onto convex sets (POCS) that iteratively uses the smoothnessassumptionand pixel orDCT value range information forerrorconcealment [17][18] Anextensiontotheassumption thatnaturalimages are smooth and the values are continuous spatially or spectrally is to adopt the Markov random fields (MRF)to model the images [19] MRF based error concealment methods were first proposedby Salama et al. 20] 22] LaterShirani ....

H. Sub and W. Kwok, Concealment of Damaged Block Transform Coded Images using Projections OntoConvex Sets , IEEETrans.onImage Processing,Vol.4,pp.470- 477,April1995.

....but not diagonal edges. Another assumption made about images is edge continuity, which implies that if an edge is present in the neighboring blocks of a missing block, and its direction indicates that it should passes through the missing block, it should be then extended to the missing block. In [7], this implication is used in a Projection Onto Convex Sets (POCS) based retrieval method. In [8] a heuristic approach which is less computationally intensive, replaces the POCS stage in the above method. Although generally more accurate than the approach proposed in [3] edge based methods are ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using pro- jection onto convex sets," IEEE Transactions image processing, vol. 4, pp. 470 477, April 1995.

....in computation by suitable bu#ering and updating of transform coe#cients. Note also that if one views the iterative use of denoising and projection onto layers as a sequence of alternating projections, it can be seen that the proposed method is substantially di#erent from approaches such as [10], since the operation of the presented algorithm cannot be simplified to a sequence of projections onto fixed, data independent, convex or nonconvex sets. Further issues related to the sensitivity to compression, computational complexity, selection of thresholds, and other results on the optimum ....

H. Sun, and W. Kwok, "Concealment of Damaged Block Transform Coded Images Using Projections onto Convex Sets," IEEE Trans. on Image Proc., Vol. 4, No. 4, Aug. 1995.

....GOB, or at least a significant part of it, is affected (i.e. 16 successive luminance lines) spatial interpolation is less efficient than temporal extrapolation. Only in the case of very complex motion or scene cuts, it can be advantageous to rely on the spatial correlation in the image [37] [38], or switch between temporal and spatial concealment [39] 32] In the simplest and most common approach, previous frame concealment, the corrupted image content is replaced by corresponding pixels from the previous frame. This simple approach yields good results for sequences with little motion ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projection onto convex sets," IEEE Trans. Image Processing, vol. 4, pp. 470--477, Apr. 1995.

....communication, intra frame coding (thus spatial interpolation for error concealment) may be preferred in order to avoid severe inter frame error propagation and to reduce the hardware complexity. Various methods have been proposed to conceal the missing data by exploiting the spatial redundancy [3, 4, 5, 6]. Most of these schemes are related to block based image and video coding techniques, probably because the most emerging image and video compression standards such as JPEG [7] H.261 [8] and MPEG [9] are all block based coding schemes. Wang et al. 3] imposed spatial and temporal smoothing ....

....al. 3] imposed spatial and temporal smoothing constraints on the reconstructed block to estimate the lost DCT coefficients. Block interleaving was incorporated to minimize the effect of packet loss so that the damaged blocks tend to be isolated and the loss recovery is facilitated. Sun and Kwok [5] utilized spatially correlated edge information from a large local neighborhood of surrounding pixels to conceal damaged blocks. Their approach can be viewed as an alternating projection onto convex set method. A fuzzy logic reasoning based approach [6] was proposed by Lee et al. for block based ....

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Proc., pp. 470-477, April 1995.

....from transmission errors is minimized. Error concealment is an extremely important component of any error robust video codec. Spatial and temporal interpolations are often utilized in error concealment methods. Examples include Maximally Smooth Recovery ( 11] Projection onto Convex Sets, [12]) and various motion vector and coding mode recovery methods such as Motion Compensated Temporal Prediction ( 13] Like the error resilience tools discussed above, the effectiveness of an error concealment strategy is highly dependent on the performance of the resynchronization scheme. If the ....

H. Sun, W. Kwok, "Concealment of damaged block transform coded images using projection onto convex sets," IEEE Trans. Image Processing, vol. 4, pp. 470-477, Apr. 1995.

....HDTV applications [6] and Jung et al. proposed an EC algorithm in the spatial domain by using the projective interpolation [7] 84 Y. L. Huang and R. F. Chang Also, Sun and Kwok proposed a spatial interpolation algorithm for the EC problem based on the projections onto convex set (POCS) theory [8]. We notice that the spatial projective interpolation schemes utilise different reconstruction rules that are decided by the edge pattern. If the block size is large or the edges in a block are irregular, the edge classification scheme will become complex and inefficient, and then the projective ....

Sun H, Kwok W. Concealment of damaged block transform coded images using projections on convex sets. IEEE Trans Image Process 1995; 4: 470--477

....while temporal interpolation is used to reconstruct the missing data in inter coded frames. In recent years, numerous error concealment schemes have been proposed in the literature (refer to Ref. 69] for a good survey) Examples include maximally smooth recovery [67] projection onto convex sets [58], and various motion vector and coding mode recovery methods suchas motion compensated temporal prediction [25] So far, we have reviewed various application layer QoS control techniques. These techniques are employed by the end systems and do not require any QoS support from the network. If the ....

H. Sun and W. Kwok, \Concealment of damaged block transform coded images using projection onto convex sets," IEEE Trans. on Image Processing, vol. 4, no. 4, pp. 470-477, April 1995.

....and the solutions under different loss patterns correspond to different interpolation filters in the spatial, temporal, and frequency domains. Spatial Interpolation Using Projection onto Convex Sets (POCS) Technique: Another way of accomplishing spatial interpolation is by using the POCS method [ 38 , 39 ]. The general idea behind POCSbased estimation methods is to formulate each constraint about the unknowns as a convex set. The optimal solution is the intersection of all the convex sets, which can be obtained by recursively projecting a previous solution onto individual convex sets. When applying ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Proc., vol. 4, no. 4, pp. 470-477, Apr. 1995.

....for real time applications since they require retransmission of ATM cells. Prioritization approaches to ATM cell loss concealment have been proposed [4, 5, 6] Techniques involving interleaving data have also been proposed [7, 8] along with post processing techniques for error concealment [9, 10, 7, 11, 12, 13]. In all of the above techniques there has been no mention of how the loss of macroblocks is detected. Furthermore, there been no reference as to how bits pertinent to one macroblock are distinguished from those belonging to another macroblock in the event that cell loss has occurred. Our approach ....

H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Transactions on Image Processing, vol. 4, no. 4, pp. 470--477, April 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded image using projections onto convex sets," IEEE Trans. Image Processing, vol. 4, no. 4, pp. 470--477, Apr. 1995.

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H. Sun and W. Kwok. Concealment of Damaged Block Transform Coded Images Using Projections onto Convex Sets. IEEE Transactions on Image Processing, 4(4):470--477, April 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded image using projections onto convex sets," IEEE Trans. Image Processing, vol. 4, no. 4, pp. 470--477, Apr. 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projection onto convex set," IEEE Trans. Image Processing, vol. 4, pp. 470--477, Apr. 1995.

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H. Sun, W. Kwok, Concealment of damaged block transform coded images using projection onto convex sets, IEEE Trans. Image Processing 4 (4) (April 1995) 470}477.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Proc., vol. 4, no. 4, pp. 470-477, Apr. 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Processing, vol. 4, pp. 470--477, Apr. 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Proc., vol. 4, no. 4, p. 470-77, April 1995.

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H. Sun and W. Kwok, "Concealment of Damaged Block Transform Coded Images Using Projections onto Convex Sets", IEEE Trans. Image Proc., vol. 4, no. 4, pp. 470-477, April 1995.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projection onto convex sets," IEEE Trans. Image Processing, vol. 4, pp. 470--477, Apr. 1995.

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H. Sun, W. Kwok, Concealment of damaged block transform coded images using projection onto convex sets, IEEE Trans. Image Processing 4 (4) (April 1995) 470}477.

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H. Sun and W. Kwok, "Concealment of damaged block transform coded images using projections onto convex sets," IEEE Trans. Image Processing,vol. IP-4, pp. 470--477, Apr. 1995.

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