Akira Minezawa

Complexity reduction of in-loop filtering for compressed image restoration in HEVC

This paper presents a method for reducing the complexity of adaptive filtering for image restoration adopted in High Efficiency Video Coding (HEVC), called Adaptive Loop Filter (ALF). Although ALF can greatly improve the PSNR of decoded frames, its impact is not uniform across an entire frame, but depends on the local texture. Based on this fact, the proposed method first predicts the effectiveness of ALF for each pixel by score calculation, and skips all ALF processes for the pixels whose scores are less than a threshold. This threshold is adaptively determined for each frame in the encoding process, and is transmitted to a decoder. Experimental evaluation clearly demonstrates that the proposed method achieves significant reduction of the computation time of ALF without noticeable encoding performance loss.

A novel video coding scheme for Super Hi-Vision

We propose a novel video coding scheme targeting Super Hi-Vision (SHV) video sources. While it takes a conventional block-based MC + Transform hybrid coding approach that is suitable for hardware implementation of a SHV video codec, the proposed scheme achieved significant coding efficiency improvement by introducing several coding tools such as intra prediction and adaptive transform. According to our experimental analysis, the proposed scheme achieves significant bit-rate saving compared to the state-of-the-art AVC/H.264 high profile.

Noise reduction for screen content coding based on local histogram

This paper proposes a noise reduction method for screen content coding using HEVC. The proposed method focuses on that the histograms of pixel values for screen content have distinct and sparse peaks respectively. This property is often degraded by the coding distortion, which arises some small peaks around the original peak. This paper presents a method for removing the small peaks derived from the noise, and its implementation to HEVC as an extension of SAO. Experimental evaluation shows that the proposed noise reduction method significantly improves the visual quality of decoded screen content with bit-rate reduction.