Hyun-Soo Kang

Fast motion estimation with adaptive search range adjustment

A fast motion estimation algorithm based on the adaptive search range adjustment (ASRA) is presented. The size of search range for each block is adaptively controlled according to the initial cost at the search center, and then the full search algorithm (FSA) is performed to find the optimal matching block in the adjusted search range. The proposed method is implemented in H.264/AVC reference software (JM) to demonstrate its efficiency over the conventional FSA.

Frame rate up-conversion method based on texture adaptive bilateral motion estimation

In this paper, a new frame rate up-conversion scheme is proposed in order to overcome motion blur problems of liquid crystal displays caused by slow responses. Conventional bilateral motion estimation methods used in the frame rate upconversion scheme present a major drawback of missing true motion vectors if there are blocks with simple textures in search range. To solve this problem, a texture adaptive bilateral motion estimation method increasing the cost value of a block with simple texture is proposed. Also a motion estimation scheme that utilizes neighboring motion vector effectively is proposed to reduce computation time required to estimate motion. Since the proposed scheme does not apply all available motion vectors within search range, the execution time of frame rate up conversion can be reduced dramatically. Experimental results show that the interpolated frame image quality is improved as well as the processing time of the proposed method is greatly reduced compared with those of conventional methods.

Reliable watermark detection method based on analysis of correlation

A digital watermark is a perceptually unobtrusive signal em- bedded in a multimedia asset, such as an image, for copyright protec- tion. In many cases watermark detection amounts to thresholding a cor- relation value between a watermark and a received image. Watermarking detection schemes can be classified into two types. Type 1 is based on a correlation process that is applied to the difference between an original image and an input image to be tested. Type 2 is based on a correlation process that is directly applied to an input image. Type 1 fails to prove the rightful ownership, while type 2 can do so. However, type 2 has a problem that type 1 does not have: The correla- tion between a watermark and an original image to be watermarked is too significant to be ignored, when it is normalized by the watermarks energy. In this paper, based on an analysis of the correlation, we pro- pose a novel watermarking scheme to minimize that effect. We verify the performance of the proposed scheme by experiments.

Dual block truncation coding for overdriving of full HD LCD driver

This paper presents an image coding method for overdriving of a 10bit Full HD LCD display considering the chip size of TCON (Timing Controller) and real-time operation. The proposed method is an adaptive scheme of AM-BTC (Absolute Moment Block Truncation Coding). It splits a sample block into two sub-blocks considering the color level distribution of the sample block and applies AMBTC to each sub-block. Experimental results show that the proposed method is superior to the conventional method in both objective and subjective visual quality.

Coding Efficiency Improvement By Applying Rate-Distortion Optimization To 3D-DCT Based Integral Image Compression Method

In this paper, we propose a rate-distortion optimization method to improve the coding efficiency of the conventional 3D-DCT based compression method using adaptive block mode selection for integral images. In the conventional 3D-DCT based compression method, 3D-DCT blocks of variable block sizes are adaptively selected depending on the characteristics of integral images, and then 3D-DCT is performed. The proposed method applies a rate-distortion optimization to determine the optimal block mode. In addition, we suggest the optimal Lagrangian parameter for integral images. Experimental results show that the proposed method gives bit-rate reduction of about 5%.

3D DCT based compression method for integral images

This paper presents an efficient compression method for the integral images where an adaptive 3D block construction is employed for three dimensional discrete cosine transform (3D-DCT). The existing 3DDCT based techniques take disadvantages in 3D block construction as applying a fixed block size and a fixed scanning regardless of the image characteristics. In this paper, therefore, we propose more flexible construction, i.e. four different block size modes and two scanning modes which are adaptively selected for coding of elemental images in an integral image. Experimental results show that the proposed method gives significant improvement in coding efficiency. In particular, at the high bit-rates, the proposed method is more efficient since the overhead bits for signalling of a block size and a scanning mode take less part of the total bits.

Fast Intra Mode Decision Algorithm Using Directional Gradients for H.264

H.264/AVC video coding standard uses the rate distortion optimization method which determines the best coding mode for macroblock(MB) to improve coding efficiency. Whereas RDO selects the best coding mode, it causes the heavy computational burden comparing with previous standards. In this paper, a fast intra prediction mode decision algorithm using two-path structure is proposed. In the first path, 16x16 intra prediction mode is determined using directional gradients. In the second path, 3 modes instead of 9 modes are chosen for RDO to decide the best mode for 4x4 block. Finally, the two modes determined in the two-path decision process are compared to decide the final block mode. Experimental results show that the computation time of the proposed method is decreased to about 77% of the exhaustive mode decision method with negligible quality loss. Keywords-component; H.264 video coding, Intra prediction

Low-complexity depth map generation for real-time 2D-to-3D video conversion

A low-complexity depth generation algorithm for 3D conversion of 2D videos is presented. For temporal consistency in global depth, a pattern-based depth generation method is introduced. In addition, refinement of depth from the combined depth cues of texture and motion is also addressed. Experimental results show that the proposed method outperforms previous algorithms in terms of the complexity and subjective quality.

Fast motion estimation algorithm combining search point sampling technique with adaptive search range algorithm

This paper presents an enhanced fast motion estimation method where a search point sampling technique is combined with the adaptive search range algorithm (ASRA) based on the distribution of motion vector differences, which is our previous work. Since the ASRA is based on downsizing of search ranges for less computational complexity rather than sub-sampling of search points that is adopted by most of the fast algorithms, it results in smaller search areas where all points are considered as search points. Therefore, the conventional fast algorithms based on search point sampling techniques such as three-step search algorithm can be easily employed to the ASRA. As a result, we propose an algorithm where a part of the points within the search areas determined by the ASRA are sampled as the search points. Experimental results show that the proposed method reduces complexity of our ASRA by about 60% without quality degradation.

Fast motion estimation based on search range adjustment using neighboring MVDs

In this paper, we propose a new adaptive search range motion estimation method for H.264/AVC where search ranges are adjusted by the probabilities of motion vector differences (MVDs). The MVDs are modeled as a discrete Laplace distribution and then its parameter is estimated by the maximum likelihood estimator. The MVDs of neighboring blocks are employed as the samples for the estimation. With the estimated distribution, the search ranges which include the correct MVDs for a prefixed probability are analytically determined. Since the proposed method handles the search ranges instead of search point sampling patterns, it provides very flexible and hardware-friendly approach in motion estimation. Experimental results show that it is very similar to the optimal method (full search algorithm) in PSNR but gives significant reduction in the computational complexity.