Faculty Publications
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Publications by NITK Faculty
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Item Implementation of JPEG2000 still image codec on blackfin (ADSP - BF535) processor(2004) Kiran, K.S.; Shivaprakash, H.; Subrahmanya, M.V.; Raj, S.; Sumam David, S.With increasing use of Multimedia in everyday life, there is a need not only for better image compression techniques which can be used in a wide range of applications but also for efficient implementation of these compression algorithms on power-efficient platforms. To cater to such needs several compression methodologies have been proposed and standardized. We have implemented, JPEG2000, an emerging standard for still image compression on the Analog Devices Blackfin Digital Signal Processor (DSP) Implementation of still-image compression on programmable DSPs offer several advantages like ease of changing the codec standard, improved value addition by customizing the codec to the target application, scalability in image sizes etc. This paper presents the implementation details of the JPEG2000 still image codec on ADSP-BF535 processor based Analog Devices EZ-kit Lite board, and the quality of the results obtained demonstrate the potential of the low-power Micro -Signal Architecture of Blackfin processor as a good choice for embedded multimedia applications.Item Implementation of JPEG2000 still image codec on blackfin (ADSP - BF535) processor(2004) Kiran, K.S.; Shivaprakash, H.; Subrahmanya, M.V.; Raj, S.; Sumam David, S.With increasing use of Multimedia in everyday life, there is a need not only for better image compression techniques which can be used in a wide range of applications but also for efficient implementation of these compression algorithms on power-efficient platforms. To cater to such needs several compression methodologies have been proposed and standardized. We have implemented, JPEG2000, an emerging standard for still image compression on the Analog Devices Blackfin Digital Signal Processor (DSP). Implementation of still-image compression on programmable DSPs offer several advantages like ease of changing the codec standard, improved value addition by customizing the codec to the target application, scalability in image sizes etc. This paper presents the implementation details of the JPEG2000 still image codec on ADSP-BF535 processor based Analog Devices EZ-kit Lite board, and the quality of the results obtained demonstrate the potential of the low-power Micro-Signal Architecture of Blackfin processor as a good choice for embedded multimedia applications.Item Depth-Based Selective Blurring in Stereo Images Using Accelerated Framework(3D Research Center 3drc@kw.ac.kr, 2014) Mukherjee, S.; Guddeti, R.M.R.Abstract: We propose a hybrid method for stereo disparity estimation by combining block and region-based stereo matching approaches. It generates dense depth maps from disparity measurements of only 18 % image pixels (left or right). The methodology involves segmenting pixel lightness values using fast K-Means implementation, refining segment boundaries using morphological filtering and connected components analysis; then determining boundaries’ disparities using sum of absolute differences (SAD) cost function. Complete disparity maps are reconstructed from boundaries’ disparities. We consider an application of our method for depth-based selective blurring of non-interest regions of stereo images, using Gaussian blur to de-focus users’ non-interest regions. Experiments on Middlebury dataset demonstrate that our method outperforms traditional disparity estimation approaches using SAD and normalized cross correlation by up to 33.6 % and some recent methods by up to 6.1 %. Further, our method is highly parallelizable using CPU–GPU framework based on Java Thread Pool and APARAPI with speed-up of 5.8 for 250 stereo video frames (4,096 × 2,304). © 2014, 3D Research Center, Kwangwoon University and Springer-Verlag Berlin Heidelberg.Item Perceptually lossless coder for volumetric medical image data(Academic Press Inc. apjcs@harcourt.com, 2017) Chandrika, B.K.; Aparna., P.; Sumam David, S.S.With the development of modern imaging techniques, every medical examination would result in a huge volume of image data. Analysis, storage and/or transmission of these data demands high compression without any loss of diagnostically significant data. Although, various 3-D compression techniques have been proposed, they have not been able to meet the current requirements. This paper proposes a novel method to compress 3-D medical images based on human vision model to remove visually insignificant information. The block matching algorithm applied to exploit the anatomical symmetry remove the spatial redundancies. The results obtained are compared with those of lossless compression techniques. The results show better compression without any degradation in visual quality. The rate-distortion performance of the proposed coders is compared with that of the state-of-the-art lossy coders. The subjective evaluation performed by the medical experts confirms that the visual quality of the reconstructed image is excellent. © 2017Item Gradient-oriented directional predictor for HEVC planar and angular intra prediction modes to enhance lossless compression(Elsevier GmbH journals@elsevier.com, 2018) Shilpa Kamath, S.; Aparna., P.; Antony, A.Recent advancements in the capture and display technologies motivated the ITU-T Video Coding Experts Group and ISO/IEC Moving Picture Experts Group to jointly develop the High-Efficiency Video Coding (HEVC), a state-of-the-art video coding standard for efficient compression. The compression applications that essentially require lossless compression scenarios include medical imaging, video analytics, video surveillance, video streaming etc., where the content reconstruction should be flawless. In the proposed work, we present a gradient-oriented directional prediction (GDP) strategy at the pixel level to enhance the compression efficiency of the conventional block-based planar and angular intra prediction in the HEVC lossless mode. The detailed experimental analysis demonstrates that the proposed method outperforms the lossless mode of HEVC anchor in terms of bit-rate savings by 8.29%, 1.65%, 1.94% and 2.21% for Main-AI, LD, LDP and RA configurations respectively, without impairing the computational complexity. The experimental results also illustrates that the proposed predictor performs superior to the existing state-of-the-art techniques in the literature. © 2018 Elsevier GmbHItem Evaluation of Superpave mixtures for perpetual asphalt pavements(Taylor and Francis Ltd. michael.wagreich@univie.ac.at, 2019) Priyanka, B.A.; Goutham, G.; Ravi Shankar, A.U.Early deterioration of flexible pavements, due to increased traffic volume, environmental conditions, poor maintenance and construction quality, causes difficulties to road users, all around the world. The structural failures such as fatigue and rutting demand the reconstruction of the pavements which further leads to significant construction cost. One potentially sustainable solution to this problem is to adopt perpetual pavement technology. The fatigue and rutting distresses in the pavements can be minimised to some extent by utilising Superpave mixtures with perpetual pavement concept. This paper proposes two polymer-modified Superpave mixtures, one with optimum amount of binder and the other with rich binder content, for the asphalt intermediate and base layers of perpetual pavement, respectively. The optimum mixtures were prepared with two aggregate gradations having nominal maximum aggregate sizes 25 mm and 19 mm for the intermediate layers to enhance the rutting resistance. Rich mixtures were prepared with the same gradations for the asphalt base layer to improve the fatigue resistance. Laboratory tests were conducted on these mixtures to determine moisture susceptibility, rutting resistance, fatigue behaviour and resilient modulus. The fatigue and rutting criteria of perpetual pavement sections were evaluated using KENPAVE software and the critical strains were found to be within the limits. The experimental results and analysis on perpetual pavement sections with proposed mixtures for the intermediate and base layers show that they can be considered as a better alternative for conventional pavements. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.Item Pixelwise improvised blend of predictors in HEVC lossless mode(Elsevier GmbH, 2020) Shilpa Kamath, S.; Aparna., P.; Antony, A.The commendable work by the two video coding pioneers ISO/IEC and ITU-T, to handle the next-generation of multimedia services has led to the evolution of High Efficiency Video Coding (HEVC) standard. The lossless mode of HEVC is essential when no loss in fidelity is desired to aide most of the real-world applications like video analytics, web collaboration, remote desktop sharing, etc. The proposed work intends to improvise the HEVC intra prediction scheme through the application of the heuristic history-based blend of predefined sub-predictors, while in lossless mode. The prime element of the locally adaptive mechanism is the derivation of the penalizing factors that are imposed on the sub-predictors, based on the neighborhood residuals. The experimental analysis highlights that the proposed method outperforms the lossless mode of HEVC anchor and the prevalent state-of-the-art prediction techniques in terms of savings in bit-rate which is achieved without any increase in run-time. © 2019 Elsevier GmbHItem Performance enhancement of HEVC lossless mode using context-based angular and planar intra predictions(Springer, 2020) Kamath, S.; Aparna., P.; Antony, A.Lossless mode of High-Efficiency Video Coding (HEVC), the state-of-the-art video coding standard, can be used for distortion-free reconstruction of the input data for a wide variety of applications. HEVC relies on the usage of efficient intra prediction strategies to achieve superior compression than its predecessor H.264. A large amount of spatial redundancy exists in almost all video sequences due to coherence, smoothness and the inherent correlation within the neighboring pixels. In this paper, a context-based intra prediction scheme is proposed to minimize this local redundancy by identifying the edges and textures to appropriately modify the prediction strategy at the pixel level, without further increase in the computational complexity. The variability in the sum of absolute differences and local pixel intensity values are chosen to derive the context of the nearby region around the target pixel in the planar and angular intra prediction modes respectively. The experimental results validate the superiority of the proposed method over the HEVC anchor and other state-of-the-art techniques in the literature. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.Item Distributed video coding based on classification of frequency bands with block texture conditioned key frame encoder for wireless capsule endoscopy(Elsevier Ltd, 2020) Sushma, B.; Aparna., P.Wireless capsule endoscopy (WCE) has provided remarkable improvement in diagnosing gastrointestinal disorders by scanning the entire digestive tract. The system still need refinement, to upgrade the quality of images, frame rate and battery life. The principal component of the system that can address these issues is low complexity video compressor. Motivated by low computational complexity requirements of WCE video encoding, this paper presents a distributed video coding framework based on frequency bands classification. The lower frequency bands are used to generate good quality side information (SI) as they exhibit high temporal correlation. This reduces the complexity of hash generation at the encoder, thus eliminating the latency in SI creation. Apart from this, SI creation involves only a simple block search and doesn't depend on Wyner–Ziv (WZ) bands. Also different approach for distributed coding of sub-sampled chroma components of WZ frame is proposed. Low complexity JPEG based key frame encoding is proposed that take advantage of WCE image textural properties to reduce the complexity of encoding smooth blocks by 81% at the quantization and encoding stage. Other novel features include use of discrete Tchebichef transform (DTT), Golomb–Rice code for entropy coding. Performance evaluation shows that the proposed method achieves 60% improvement in compression over Motion JPEG with low computational complexity. © 2020 Elsevier LtdItem A Mixed Parallel and Pipelined Efficient Architecture for Intra Prediction Scheme in HEVC(Taylor and Francis Ltd., 2022) Poola, L.; Aparna., P.The complexity of intra prediction in High-Efficiency Video Coding (HEVC) is increased significantly due to the incorporation of inherent features like variable-sized quadtree partitioned coding units and 35 angular modes that help in achieving better compression. This paper presents an efficient hardware architecture for the intra prediction that supports and comprises the above aspects and achieves a higher throughput to support high definition (HD) videos. A compact reusable reference buffer structure is implemented to limit the buffer size to 1 KB. A dedicated arithmetic unit to take advantage of the parallelism present in the prediction algorithm is incorporated, which allows the reuse of multipliers to reduce hardware resources. The loading of reference samples to buffers for prediction causes significant delays which are eliminated in our design. The entire architecture functions as a pipelined unit with no data dependency and generates eight samples/clock cycle in parallel. The design is implemented on a Field Programmable Gate Array (FPGA) platform operating at a frequency of 110 MHz. This makes it possible to support 4 K videos at 30 frames per second, with the resource cost of 16 K logic gates and 122 registers. © 2022 IETE.