Quadtree Partitioning Scheme Research Articles

Quadtree partitioning scheme of color image based

Image segmentation is an essential complementary process in digital image processing and computer vision, but mostly utilizes simple segmentation techniques, such as fixed partitioning scheme and global thresholding techniques due to their simplicity and popularity, in spite of their inefficiency. This paper introduces a new split-merge segmentation process for a quadtree scheme of colour images, based on exploiting the spatial and spectral information embedded within the bands and between bands, respectively. The results show that this technique is efficient in terms of quality of segmentation and time, which can be used in standard techniques as alternative to a fixed partitioning scheme.

Quadtree partitioning scheme of color image based

Image segmentation is an essential complementary process in digital image processing and computer vision, but mostly utilizes simple segmentation techniques, such as fixed partitioning scheme and global thresholding techniques due to their simplicity and popularity, in spite of their inefficiency. This paper introduces a new split-merge segmentation process for a quadtree scheme of colour images, based on exploiting the spatial and spectral information embedded within the bands and between bands, respectively. The results show that this technique is efficient in terms of quality of segmentation and time, which can be used in standard techniques as alternative to a fixed partitioning scheme.

A collaborative representation face classification on separable adaptive directional wavelet transform based completed local binary pattern features

Face recognition has emerged as the most active area of research in computer vision. A variety of face recognition methods were devised, though several challenges are imposed due to face variations such as facial expression, pose variation and illumination variation which generate great concern in developing efficient face recognition methods. It is desirable to extract robust local descriptive features to effectively represent such face variations. The essential attribute of the proposed method is to extract directional descriptive local features based on the face image characteristics. In order to extract the multi-resolution directional features as per the face variations, a 2-D interpolation-based separable adaptive directional wavelet transform (SADIWT) is proposed. For the implementation of 2-D SADIWT, a set of seven directions with an improved quadtree partitioning scheme is proposed. Completed local binary patterns (CLBP) superior to local binary patterns (LBP) in extracting local texture features are applied on top level’s 2-D SADIWT sub-bands to obtain local descriptive features. Collaborative representation classification (CRC) takes benefit of these descriptive features and leads to a very competitive classification performance. Extensive experimental results on benchmark face databases such as ORL, FERET, CMU-PIE, and LFW demonstrate high classification accuracy of the proposed method. A comparison with numerous methods which include various holistic, LBP-based descriptors and representation methods demonstrate the efficacy of the proposed method. Experiments are also conducted to exhibit the robustness and discrimination capability of the proposed method for handling single image per person (SIPP) and random block occlusion problem.

Efficiency of adaptive fractal image compression with archetype classification and its modifications

The DCT-based JPEG image compression technique is a standard for lossy image compression. But the technique is not suitable at high compression ratios. Again, it is resolution dependent. Alternative compression techniques are introduced to reduce these problems. One such popular technique is fractal-based image compression. In this paper, efficiency of a fractal-based image compression technique is discussed that applies adaptive quadtree partitioning and archetype classification schemes. The adaptive quadtree partitioning scheme is dependent on image pixel context to share some self-similar structure of the image and improves the decoded image quality significantly. The archetype classification scheme tries to base the technique on finding better covering of range by domain that suites better in fractal image compression techniques. Then, modification of the same is also done to enhance the performance by applying dictionary-based loss-less data compression techniques, i.e. OLZW on the fractal compressed image that is basically a collection of affine transforms. The affine transform consists of a number of parameters that are compressed using OLZW technique. After that, the same experiment is carried out by a variant of OLZW, i.e. MOLZW. The experimental results are compared among existing and modified techniques. The modified versions yield not only better image quality but also high encoding speed than their counterparts.

Quadtree partitioning and extended weighted finite automata-based fractal colour video coding

Fractal coding technique has become the most popular coding technique in the recent development of image/video compression technologies for its better performance, achieving a high compression ratio, less decoding time and good reconstruction quality of image. This paper elaborates on the approach which is a combination of a quadtree partitioning scheme and extended weighted finite automata (EWFA) coding for fractal video compression based on the concept of intra-frame coding. The quadtree partitioning scheme is used to specify the address of each sub-image. It is observed that any image can be represented by the quadtree-based EWFA; the quadtree-based EWFA coding process is similar to fractal coding process; and also the size of domain pool increases dynamically during the process of quadtree-based EWFA encoding as that of in fractal coding. Experimentations are carried on standard databases like Soccer, Suzie, Bus, Football, Xylophone, Paris, Traffic, Akiyo, Ice and mobile sequence. The developed basic fractal image compression existing mechanism is also further implemented on video/image sequences based on the concept of intra-frame coding used for comparing the results with the proposed approach. Experimental results show that the EWFA encoding/decoding process improves the quality, compression ratio, encoding and decoding time of reconstructed image sequence.

Fractal image coding algorithm using particle swarm optimisation and hybrid quadtree partition scheme

In this study, a novel fractal image coding algorithm using particle swarm optimisation (PSO) and hybrid quadtree partition (QP) scheme is proposed. A method called PSO strategy based on range block classification (PSO-RC) is presented instead of utilising the PSO method in the whole range pool. This new idea can enhance the compression ratio significantly and speed up the encoder. Moreover, a PSO-RC hybrid QP (PSO-RCQP) scheme is adopted in order to improve the quality of the retrieved image further. Firstly, the range blocks are divided into two categories based on the standard deviation feature. Secondly, the range blocks are encoded using either the PSO approach or storing the average pixel values directly. Thirdly, the range blocks with large matching errors when using PSO scheme employ the proposed QP method. The simulation results show that the proposed algorithm can obtain good quality and higher compression ratio other than shorten the encoding time.

Object-based stereo video compression using fractals and shape-adaptive DCT

Based on the classical fractal video compression method, an improved object-based stereo video compression scheme with Shape-Adaptive DCT is proposed in this paper. Firstly, we use more effective macroblock partition scheme instead of classical quadtree partition scheme; thus reducing the block searching strategy. The stereo fractal video coding is proposed which matches the macroblock with two reference frames in left and right view results in increasing compression ratio and reducing bit rate when transmitting compressed stereo data. The stereo codec combines the Motion Compensation Prediction (MCP) and Disparity Compensation Prediction (DCP). Fractal coding is adopted and each object is encoded independently by a prior video segmentation alpha plane, which is defined exactly as in MPEG-4. The testing results with the nature monocular and stereo video sequences provide promising performances at low bit rate coding. We believe it will be a powerful and efficient technique for the object-based monocular and stereo video sequences coding.

A novel fractal monocular and stereo video codec with object-based functionality

Based on the classical fractal video compression method, an improved monocular fractal compression method is proposed which includes using more effective macroblock partition scheme instead of classical quadtree partition scheme; using improved fast motion estimation to increase the calculation speed; using homo-I-frame like in H.264, etc. The monocular codec uses the motion compensated prediction (MCP) structure. And stereo fractal video coding is proposed which matches the macroblock with two reference frames in left and right views, and it results in increasing compression ratio and reducing bit rate/bandwidth when transmitting compressed video data. The stereo codec combines MCP and disparity compensated prediction. And a new method of object-based fractal video coding is proposed in which each object can be encoded and decoded independently with higher compression ratio and speed and less bit rate/bandwidth when transmitting compressed stereo video data greatly. Experimental results indicate that the proposed monocular method can raise compression ratio 3.6 to 7.5 times, speed up compression time 5.3 to 22.3 times, and improve the image quality 3.81 to 9.24 dB in comparison with circular prediction mapping and non-contractive interframe mapping. The PSNR of the proposed stereo video coding is about 0.17 dB higher than that of the proposed monocular video coding, and 0.69 dB higher than that of JMVC 4.0 on average. Comparing with the bit rate resulted by the proposed monocular video coding and JMVC 4.0, the proposed stereo video coding achieves, on average, 2.53 and 21.14 Kbps bit rate saving, respectively. The proposed object-based fractal monocular and stereo video coding methods are simple and effective, and they make the applications of fractal monocular and stereo video coding more flexible and practicable.

An improved no-search fractal image coding method based on a modified gray-level transform

In this paper, we propose a fast no-search fractal image coding algorithm based on a modified gray-level transform. To improve the possibility of successful matching for a range block and a domain block, we introduce a modified gray-level transform with more transform parameters than proposed by Tong and Pi to encode the blocks. Then, we suggest a no-search fractal image coding method using two gray-level transforms, one for the large blocks and the other for the small blocks based on the quadtree partition scheme, to speed up the encoding time and improve the quality of the reconstructed images.

Design of a filter against artifacts for JPEG2000

JPEG2000 Standard (ISO/IEC 15444, ITU-T T.800) is a new-generation image compression technique, enabling encoding images at low bit rates with acceptable quality. Since JPEG2000 is based on wavelet transforms, the reconstructed image will contain perceivable ringing artifacts in medium- and low-bit-rate regimes of lossy compression. We utilize a quad-tree partitioning scheme for postprocessing the reconstructed image in a spatially varying manner and presents a voting strategy to determine a set of morphological filters to be used for reducing the ringing artifacts. All this processing is performed at the encoder side, and the set of selected filters is conveyed to the decoder in the form of side information. Specifically, the adopted (eight) morphological filters are generated through the use of four predefined structuring elements (SEs) in conjunction with two morphological operations, namely, dilation and erosion. A voting strategy is used to select the morphological filter for each partition block to optimize the postprocessed image quality—through minimizing the sum of absolute differences under the constraint of a fixed quad-tree partition. Applying the chosen morphological filters to their corresponding blocks typically enhances the reconstruction quality—in the worst case, leaving it unchanged. Simulation results demonstrate that the proposed technique enhances reconstructed image quality compared to unprocessed JPEG2000 output at an equivalent bit rate, accounting for the side information overhead, in terms of both peak SNR (PSNR) and visible ringing measure (VRM).