Woo-Shik Kim

• Ph.D.
• Engineer at Qualcomm

In this paper, an in-loop color space transform is proposed for screen content video coding to improve coding efficiency. The transform converts the color space of an input block to a better color space to improve rate-distortion performance by decorrelating among color components. Specifically, to derive the optimal color transform the principal c...

The screen content coding (SCC) Extensions of high efficiency video coding (HEVC) employs in-loop adaptive color-space transform (ACT) technique to explore the inter-color-component redundancy, i.e., statistical redundancy among different color components. In ACT, the prediction residual signal is adaptively converted into a different color space,...

In order to improve 3-D video coding efficiency, we propose methods to estimate rendered view distortion in synthesized views as a function of the depth map quantization error. Our approach starts by calculating the geometric error caused by the depth map error based on the camera parameters. Then, we estimate the rendered view distortion based on...

An apparatus and method for encoding and decoding an image are provided. The image decoding method includes decoding luma blocks according to a predetermined decoding mode of each of the luma blocks, and decoding chroma blocks according to the predetermined decoding mode of each of the luma blocks.

Video coding in the YCbCr color space has been widely used, since it is efficient for compression, but it can result in color distortion due to conversion error. Meanwhile, coding in RGB color space maintains high color fidelity, having the drawback of a substantial bit-rate increase with respect to YCbCr coding. Cross-component prediction (CCP) ef...

A coding method including dividing pixels of a chrominance component of an input image into blocks having a predetermined size; selecting one among a direct current prediction method, a vertical prediction method, a horizontal prediction method, and a hybrid prediction method according to a user's input; generating a prediction value of each pixel...

In this chapter, we discuss unique characteristics of depth maps, review recent depth map coding techniques, and describe how texture and depth map compression can be jointly optimized. © Springer Science+Business Media New York 2013. All rights are reserved.

Sample adaptive offset (SAO) is the new in-loop filter in High Efficiency Video Coding (HEVC) standard. In this paper, the problems in the early version of SAO technique is discussed, and it is shown how the proposed methods improve its performance. It is proposed to restrict edge offset sign according to edge shape to reduce visual artifact caused...

An encoding system may generate an edge map based on a pixel value difference between neighboring pixels in an inputted image, generate a graph by connecting pixels using the generated edge map, select a prediction value for at least one pixel based on the generated graph, and encode an image based on the selected prediction value.

A method and apparatus for coding a chrominance component of an intra-image using spatial predictive coding and a method and apparatus for decoding the coded chrominance component are provided. The coding apparatus includes a variation calculator, which calculates a vertical variation and a horizontal variation with respect to a current block to be...

In this paper a graph-based transform is proposed as an alternative to the discrete cosine transform. An image or video signal is represented as a graph signal, where the graph is generated so as not to cross an image edge in a local region, i.e., square block. Then, spectral representation of graph signal is used to form transform kernels by findi...

Depth map compression is important for compact “texture-plus-depth” representation of a 3D scene, where texture and depth maps captured from multiple camera viewpoints are coded into the same format. Having received such format, the decoder can synthesize any novel intermediate view using texture and depth maps of two neighboring captured views via...

To improve rendered view quality in a 3-D video system, we propose to encode and transmit depth transition data, which represents, for each pixel in a frame, the location in between two existing views where the depth corresponding to that pixel changes. Given the highly localized and non-linear characteristics of rendered view distortion, it is pos...

In this work a new set of edge-adaptive transforms (EATs) is presented as an alternative to the standard DCTs used in image and video coding applications. These transforms avoid filtering across edges in each image block, thus, they avoid creating large high frequency coefficients. These transforms are then combined with the DCT in H.264/AVC and a...

The objective of this work is to develop a new 3-D video coding system which can provide better coding efficiency with improved subjective quality as compared to existing 3-D video systems. We have analyzed the distortions that occur in rendered views generated using depth image based rendering (DIBR) and classified them in order to evaluate their...

This work proposes a new intra prediction coding scheme for depth map images used in view interpolation. The main goal is to design a prediction scheme which can reduce the prediction error energy in blocks with arbitrary edge shapes. This will reduce the rate needed to encode such blocks while also eliminating some of the annoying artifacts caused...

New data formats that include both video and the corresponding depth maps, such as multiview plus depth (MVD), enable new video applications in which intermediate video views (virtual views) can be generated using the transmitted/stored video views (reference views) and the corresponding depth maps as inputs. We propose a depth map coding method ba...

Video representations that support view synthesis based on depth maps, such as multiview plus depth (MVD), have been recently proposed, raising interest in efficient tools for depth map coding. In this paper, we derive a new distortion metric that takes into consideration camera parameters and global video characteristics in order to quantify the e...

This paper presents a technique for coding high dynamic range videos. The proposed coding scheme is scalable, such that both standard dynamic range and high dynamic range representations of a video can be extracted from one bit stream. A localized inverse tone mapping method is proposed for efficient inter-layer prediction, which applies a scaling...

The chrominance subsampling has been widely used for the image and video compression. However, this can cause color distortion and image quality degradation. We developed a new sampling method in which the residual image after intra or inter prediction is subsampled instead of the original image subsampling. Since the residual image contains fewer...

This paper presents a new color transform (YSbSr) that increases the coding efficiency for RGB space by reducing the conversion error and coding error propagation that happen during the color space conversion. Traditionally the use of color transforms has been limited to maintain the compatibility with black-and-white transmission. But for high qua...

This paper presents an efficient video coding method in RGB space. Generally RGB space is regarded as a bad space from a compression point of view. Each RGB component contains the color information along with luminance information. This redundancy degrades the coding efficiency. To exploit the intercolor redundancy, the RGB space is usually convert...

Motion compensation is a powerful method to compress a video sequence. However, once an error occurs, the error propagates through the frames. Recently, the intra update method was proposed to stop the error propagation at the cost of the compression efficiency. This paper proposes an intra update method based on rate-distortion optimization in err...

Moving picture experts group (MPEG)-4 visual conformance standard specifies methods to verify whether bitstreams and decoders meet the requirements at a specified profile and level. The test of decoders can be divided into two parts: static and dynamic tests. The static test can be performed by comparing images from a decoder under test with those...

To automatically construct a three-dimensional (3-D) object model, it is necessary to merge a set of range images acquired from different views. The iterative closest point (ICP) algorithm has been widely used to find the transformation parameters between a pair of images. In this paper, a fast ICP algorithm is proposed by restricting the search sp...

This paper presents a new paradigm of the video compression technology, which radically reforms the conventional video coding process. A camera captures images in RGB domain that is suitable for the natural color representation. But, generally RGB space is regarded as a bad space from a compression point of view. To solve this problem, the RGB spac...