Pub Date : 2009-03-21DOI: 10.1049/IET-IPR.2008.0042
C. C. Lin, Y. Lin, H. Hsieh
Many efficient search algorithms such as three-step search, new three-step search, four-step search, block-based gradient descent search, diamond search and hexagon-based search are developed for block motion estimation (ME) to search for the optimal objective function. The block ME technique involves an optimisation problem. Although these algorithms can converge to a minimal point rapidly, they suffer from becoming trapped in local minimum if the objective function has multiple minima. To solve this problem, the hybrid multi-hexagon-grid search (UMHexagonS) algorithm has been proposed in H.264/AVC, in which an unsymmetrical-cross search and an uneven UMHexagonS are employed over a wide search range to find a nearly global minimum. The experiment shows that the hybrid UMHexagonS algorithm is computation expensive and is occasionally trapped in local minimum. The authors propose a novel and fast search algorithm, called multi-direction search (MDS) algorithm, which uses an MDS first to find all possible locally optimal points and then uses the extended hexagon search to refine these points for the final optimal motion vector. The experimental results indicate that a significant improvement in computation reduction (∼30 and 50% reduction in average search points, corresponding to 19 and 37% reduction in total encoding time, for MDS and fast MDS, respectively) can be achieved while maintaining better coding performance, compared with the hybrid UMHexagonS algorithm.
{"title":"Multi-direction search algorithm for block motion estimation in H.264/AVC","authors":"C. C. Lin, Y. Lin, H. Hsieh","doi":"10.1049/IET-IPR.2008.0042","DOIUrl":"https://doi.org/10.1049/IET-IPR.2008.0042","url":null,"abstract":"Many efficient search algorithms such as three-step search, new three-step search, four-step search, block-based gradient descent search, diamond search and hexagon-based search are developed for block motion estimation (ME) to search for the optimal objective function. The block ME technique involves an optimisation problem. Although these algorithms can converge to a minimal point rapidly, they suffer from becoming trapped in local minimum if the objective function has multiple minima. To solve this problem, the hybrid multi-hexagon-grid search (UMHexagonS) algorithm has been proposed in H.264/AVC, in which an unsymmetrical-cross search and an uneven UMHexagonS are employed over a wide search range to find a nearly global minimum. The experiment shows that the hybrid UMHexagonS algorithm is computation expensive and is occasionally trapped in local minimum. The authors propose a novel and fast search algorithm, called multi-direction search (MDS) algorithm, which uses an MDS first to find all possible locally optimal points and then uses the extended hexagon search to refine these points for the final optimal motion vector. The experimental results indicate that a significant improvement in computation reduction (∼30 and 50% reduction in average search points, corresponding to 19 and 37% reduction in total encoding time, for MDS and fast MDS, respectively) can be achieved while maintaining better coding performance, compared with the hybrid UMHexagonS algorithm.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79966080","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-21DOI: 10.1049/IET-IPR.2007.0220
P. Tsai
Reversible data hiding is required and preferable in many applications such as medical diagnosis, military, law enforcement, fine art work and so on. The author proposes to use reversible data hiding applications with a vector quantisation (VQ)-compressed image. The histogram of the prediction VQ-compressed image is explored. The prediction VQ encoded image is identical to traditional VQ encoding. The index of prediction encoded VQ images is modified to embed secret data. Furthermore, the VQ images can be completely reconstructed by the recovery procedure. The experimental results show the performance of the proposed method and the efficiency of the embedding, extraction and recovery procedures. In comparison with other VQ-based schemes, the proposed method provides a higher hiding capacity and a better stego-image quality. Also, the lossless VQ image is recovered.
{"title":"Histogram-based reversible data hiding for vector quantisation-compressed images","authors":"P. Tsai","doi":"10.1049/IET-IPR.2007.0220","DOIUrl":"https://doi.org/10.1049/IET-IPR.2007.0220","url":null,"abstract":"Reversible data hiding is required and preferable in many applications such as medical diagnosis, military, law enforcement, fine art work and so on. The author proposes to use reversible data hiding applications with a vector quantisation (VQ)-compressed image. The histogram of the prediction VQ-compressed image is explored. The prediction VQ encoded image is identical to traditional VQ encoding. The index of prediction encoded VQ images is modified to embed secret data. Furthermore, the VQ images can be completely reconstructed by the recovery procedure. The experimental results show the performance of the proposed method and the efficiency of the embedding, extraction and recovery procedures. In comparison with other VQ-based schemes, the proposed method provides a higher hiding capacity and a better stego-image quality. Also, the lossless VQ image is recovered.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84502668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-21DOI: 10.1049/IET-IPR.2008.0053
Ling X. Li, Meng-Xin Guo, Zhensong Wang
Rate and quality-constrained rate control is very effective for video applications, since it can maintain constant quality while eliminating local rate spikes. An adaptive rate control method based on image activity measures (ARCIAM) is proposed for Motion JPEG2000. The algorithm can efficiently adjust the compressed bit rates to meet the rate and quality constraints for different types of colour sequences. It predicts the rate-distortion (RD) slope thresholds for frames based on image activity measure (IAM) before entropy coding. Thus, the encoding of unnecessary coding passes can be avoided. Experimental results show that the proposed method can meet the quality and rate constraints, and can achieve quality performance comparable to post-compression rate distortion optimisation at the same bit rate. Under 3 bpp and 40 dB constraints, ARCIAM can reduce the total encoding time and tier-1 encoding time for sequences by more than 20 and 30 , respectively. Moreover, the memory requirement for buffering bit-streams and RD-slope information is reduced by more than 30 on average. Besides, the method can be incorporated into the line-based JPEG2000 encoding system easily, and has been implemented on Kakadu.
{"title":"Adaptive rate control for Motion JPEG2000","authors":"Ling X. Li, Meng-Xin Guo, Zhensong Wang","doi":"10.1049/IET-IPR.2008.0053","DOIUrl":"https://doi.org/10.1049/IET-IPR.2008.0053","url":null,"abstract":"Rate and quality-constrained rate control is very effective for video applications, since it can maintain constant quality while eliminating local rate spikes. An adaptive rate control method based on image activity measures (ARCIAM) is proposed for Motion JPEG2000. The algorithm can efficiently adjust the compressed bit rates to meet the rate and quality constraints for different types of colour sequences. It predicts the rate-distortion (RD) slope thresholds for frames based on image activity measure (IAM) before entropy coding. Thus, the encoding of unnecessary coding passes can be avoided. Experimental results show that the proposed method can meet the quality and rate constraints, and can achieve quality performance comparable to post-compression rate distortion optimisation at the same bit rate. Under 3 bpp and 40 dB constraints, ARCIAM can reduce the total encoding time and tier-1 encoding time for sequences by more than 20 and 30 , respectively. Moreover, the memory requirement for buffering bit-streams and RD-slope information is reduced by more than 30 on average. Besides, the method can be incorporated into the line-based JPEG2000 encoding system easily, and has been implemented on Kakadu.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76889947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-21DOI: 10.1049/IET-IPR.2008.0045
P. Shankar
Speckle in ultrasonic image systems adversely impacts the contrast and resolution in the image. This poses serious problems in the interpretation of B mode images of internal organs such as breast, liver, kidney and so on. In the absence of sufficient contrast, classifying the regions of interest into benign and malignant masses becomes error prone. Since some of the masses are uniquely identified in terms of the boundaries, poor contrast and resolution will result in difficulties with their identification. A new class of spatial filters based on cylindrical Bessel functions of the first kind is proposed for speckle reduction. These filters with complex impulse responses were explored for enhancing the contrast of speckled images. Hypothesising that the phase of the filtered image carries boundary information, the phase characteristics of four speckled images are also studied for detecting boundaries. Results indicate that these filters do improve the contrast and enhance the boundaries. It is shown that the phase map clearly indicates the existence of boundaries. A simple thresholding applied to the phase highlights the boundaries. The results show the strength of the Bessel spatial filters in improving contrast and highlighting boundaries without resorting to any additional edge-detection algorithms.
{"title":"Contrast enhancement and phase-sensitive boundary detection in ultrasonic speckle using Bessel spatial filters","authors":"P. Shankar","doi":"10.1049/IET-IPR.2008.0045","DOIUrl":"https://doi.org/10.1049/IET-IPR.2008.0045","url":null,"abstract":"Speckle in ultrasonic image systems adversely impacts the contrast and resolution in the image. This poses serious problems in the interpretation of B mode images of internal organs such as breast, liver, kidney and so on. In the absence of sufficient contrast, classifying the regions of interest into benign and malignant masses becomes error prone. Since some of the masses are uniquely identified in terms of the boundaries, poor contrast and resolution will result in difficulties with their identification. A new class of spatial filters based on cylindrical Bessel functions of the first kind is proposed for speckle reduction. These filters with complex impulse responses were explored for enhancing the contrast of speckled images. Hypothesising that the phase of the filtered image carries boundary information, the phase characteristics of four speckled images are also studied for detecting boundaries. Results indicate that these filters do improve the contrast and enhance the boundaries. It is shown that the phase map clearly indicates the existence of boundaries. A simple thresholding applied to the phase highlights the boundaries. The results show the strength of the Bessel spatial filters in improving contrast and highlighting boundaries without resorting to any additional edge-detection algorithms.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79299058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-02-03DOI: 10.1049/IET-IPR:20080088
G. Lee, Hongfei Lin, M.-J. Wang
An efficient rate control algorithm based on the content-adaptive initial quantisation parameter (QP) setting scheme and the peak signal-to-noise ratio (PSNR) variation-limited bit-allocation strategy for low-complexity mobile applications is presented. This algorithm can efficiently measure the residual complexity of intra-pictures without performing the computation-intensive intra-prediction and mode decision in H.264/AVC, based on the structural and statistical features of local textures. This can adaptively set proper initial QP values for versatile video contents. In addition, this bit-allocation strategy can effectively distribute bit-rate budgets based on the monotonic property to enhance overall coding efficiency while maintaining the consistency of visual quality by limiting the variation of quantisation distortion. The experimental results reveal that the proposed algorithm surpasses the conventional rate control approaches in terms of the average PSNR from 0.34 to 0.95 dB. Moreover, this algorithm provides more impressive visual quality and more robust buffer controllability when compared with other algorithms.
{"title":"Rate control algorithm based on intra-picture complexity for H.264/AVC","authors":"G. Lee, Hongfei Lin, M.-J. Wang","doi":"10.1049/IET-IPR:20080088","DOIUrl":"https://doi.org/10.1049/IET-IPR:20080088","url":null,"abstract":"An efficient rate control algorithm based on the content-adaptive initial quantisation parameter (QP) setting scheme and the peak signal-to-noise ratio (PSNR) variation-limited bit-allocation strategy for low-complexity mobile applications is presented. This algorithm can efficiently measure the residual complexity of intra-pictures without performing the computation-intensive intra-prediction and mode decision in H.264/AVC, based on the structural and statistical features of local textures. This can adaptively set proper initial QP values for versatile video contents. In addition, this bit-allocation strategy can effectively distribute bit-rate budgets based on the monotonic property to enhance overall coding efficiency while maintaining the consistency of visual quality by limiting the variation of quantisation distortion. The experimental results reveal that the proposed algorithm surpasses the conventional rate control approaches in terms of the average PSNR from 0.34 to 0.95 dB. Moreover, this algorithm provides more impressive visual quality and more robust buffer controllability when compared with other algorithms.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88024851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-02-03DOI: 10.1049/IET-IPR:20080012
Apostolos Marakakis, N. Galatsanos, A. Likas, A. Stafylopatis
A new relevance feedback (RF) approach for content-based image retrieval is presented. This approach uses Gaussian mixture (GM) models of the image features and a query that is updated in a probabilistic manner. This update reflects the preferences of the user and is based on the models of both the positive and negative feedback images. The retrieval is based on a recently proposed distance measure between probability density functions, which can be computed in closed form for GM models. The proposed approach takes advantage of the form of this distance measure and updates it very efficiently based on the models of the user-specified relevant and irrelevant images. It is also shown that this RF framework is fairly general and can be applied in case other image models or distance measures are used instead of those proposed in this work. Finally, comparative numerical experiments are provided, which that demonstrate the merits of the proposed RF methodology and the use of the distance measure, and also the advantages of using GMs for image modelling.
{"title":"Probabilistic relevance feedback approach for content-based image retrieval based on gaussian mixture models","authors":"Apostolos Marakakis, N. Galatsanos, A. Likas, A. Stafylopatis","doi":"10.1049/IET-IPR:20080012","DOIUrl":"https://doi.org/10.1049/IET-IPR:20080012","url":null,"abstract":"A new relevance feedback (RF) approach for content-based image retrieval is presented. This approach uses Gaussian mixture (GM) models of the image features and a query that is updated in a probabilistic manner. This update reflects the preferences of the user and is based on the models of both the positive and negative feedback images. The retrieval is based on a recently proposed distance measure between probability density functions, which can be computed in closed form for GM models. The proposed approach takes advantage of the form of this distance measure and updates it very efficiently based on the models of the user-specified relevant and irrelevant images. It is also shown that this RF framework is fairly general and can be applied in case other image models or distance measures are used instead of those proposed in this work. Finally, comparative numerical experiments are provided, which that demonstrate the merits of the proposed RF methodology and the use of the distance measure, and also the advantages of using GMs for image modelling.","PeriodicalId":13486,"journal":{"name":"IET Image Process.","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2009-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74303587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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