Osamu Sugimoto

Objective measurement scheme for perceived picture quality degradation caused by MPEG encoding without any reference pictures

The rapid progress in digital transmission technology has spurred demand for developing a technology that supports monitoring of video transmissions. Automating the picture quality assessment process is in particular demand because it currently depends on subjective assessments by human operators and places a heavy burden on them. The authors therefore propose an objective picture quality measurement method that works without reference pictures. In this proposed method, invisible markers are embedded into original pictures by use of the spread spectrum data hiding method. Since the markers are widely spread over the frequency domain, the degradation caused by MPEG compression can be estimated by detecting the extent of marker degradation. Our method is usable regardless of the kind of picture, bitrate, and number of stages of tandem codec connections. The degradation in picture quality caused by the embedded markers is quite small and not perceivable by the human eye. The proposed method is therefore applicable to a wide range of visual transmission services.

Objective perceptual picture quality measurement method for high-definition video based on full reference framework

The authors study a method for objective measurement of perceived picture quality for high definition video based on the full reference framework. The proposed method applies seven spatio-temporal image features to estimate perceived quality of pictures degraded by compression coding. Computer simulation shows that the proposed method can estimate perceived picture quality at a correlation coefficient of above 0.91.

No reference metric of video coding quality based on parametric analysis of video bitstream

In this paper, we propose a novel method to measure the perceived picture quality of H.264 coded video based on parametric analysis of the coded bitstream. The parametric analysis means that the proposed method utilizes only bitstream parameters, while it does not have any access to the baseband signal (pixel level information) of the decoded video. The proposed method extracts quantiser-scale, slice type and transformed coefficients from each macroblock. These parameters are used to calculate spatiotemporal image features to reflect coding artifacts which have a strong relation to the subjective quality. A computer simulation shows that the proposed method can estimate the subjective quality at a correlation coefficient of 0.867 whereas the PSNR metric, which is referred to as a benchmark, correlates the subjective quality at a correlation coefficient of 0.773.

Development of picture quality monitoring system for IPTV service based on the reduced reference framework

The authors developed a software-based realtime IPTV monitoring system based on Reduced Reference framework, and evaluated the proposed system. One of the quality issues of the IPTV service is the picture quality degradation caused by packet loss. The proposed system precisely estimates the PSNR of the corrupted received picture by extracting and comparing image features from transmission and receiver side. Computer simulations show that PSNR estimation with a 0.945 correlation coefficient at a data channel bitrate of 36kbps is possible using the proposed system.

Method of estimating perceived video quality for mobile multimedia application based on full reference framework

The authors study a method of estimating perceived picture quality for multimedia applications based on the full reference framework. Since multimedia applications usually have less capability in display and communication channels than television broadcasting, an objective quality model should be developed considering a low-resolution, low-framerate video format and low-bit-rate video coding that applies a high compression ratio. The proposed method therefore applies the blockiness of the picture, time variance of MSE and temporal PSNR degradation as indices of objective picture quality. Computer simulation shows that the proposed method can estimate perceived picture quality at a correlation coefficient of above 0.94.

Remote monitoring scheme for output video of standards convertors

As digital television transmission is becoming ubiquitous, a method that can remotely monitor the quality of the final and intermediate pictures is urgently needed. In particular, the case where standards conversion is included in the transmission chain is a serious issue as the input and output cannot simply be compared. This letter proposes a novel method to solve this issue. The combination of skipping fields/pixels and the previously proposed SSSWHT-RR method, using the information of correlation coefficients and variance of the picture, achieves accurate detection of picture failure.

Method for remote monitoring of transmitted video quality using very low bitrate data circuit based on the reduced reference method

A method to estimate the PSNR of transmitted video quality based on the reduced reference method is proposed. We previously studied PSNR estimation using the image feature extraction method based on the spread spectrum and Walsh-Hadamard transform (WHT); however, the conventional method is problematic because large bandwidth is required for the transmission of image features. We therefore propose an improved method that reduces the information amount of the image features. The image feature is expressed by the parity of the quantized level of the WHT coefficients and requires only 1 bit for one image feature while the conventional method requires 8-11 bits for each image feature. Computer simulations show that precise picture quality evaluation is possible at one eighth as much bitrate of the data circuit as the conventional method.

Method for precise detection of local impairment of coded video using reduced reference

A novel method of detecting local impairment of the coded picture caused by transmission failure on digital television transmission using a reduced reference framework is proposed. The method utilizes the SSSWHT method, which is based on spread spectrum and extraction of WHT coefficients, and precisely estimates the MSE in a small region within the frame using reduced references to detect local impairment caused by MPEG bitstream error. Computer simulations show that the proposed method detects the impaired frames completely at a reference path bitrate of 425 kbps. The method also detects slices that have impaired pixel blocks with accuracy of approximately 70% at a reference path bitrate of 425 kbps. These results confirm that the proposed method is effective for television transmission monitoring.