In this paper, we consider the relationship between human preference and brain activity, especially pulse wave information using NIRS. First of all, we extracted the information of on pulse wave from the Hb changes signal of NIRS. By using the FFT to the Hb signals, we found out the 2-nd peak of power spectrum that is implying the frequency information of the pulse wave. The frequency deviation of 2-nd peak may have some information about the change of brain activity, it is associated with the human preference for viewing the significant image content.

High dynamic range (HDR) images that include large differences in brightness levels are studied to address the lack of knowledge on the quality estimation method for real HDR images. For this, we earlier proposed a new metric, the independent signal-to-noise ratio (ISNR), using the independent pixel value as the signal instead of the peak value (PSNR). Next, we proposed the local peak signal-to-noise ratio (LPSNR), using the maximum value of neighboring pixels, as an improved version. However, these methods did not sufficiently consider human perception. To address this issue, here we proposed an objective estimation method that considers spatial frequency characteristics based on the actual brightness. In this method, the approximated function for human characteristics is calculated and used as a 2D filter on an FFT for spatial frequency weighting. In order to confirm the usefulness of this objective estimation method, we compared the results of the objective estimation with a subjective assessment. We used the organic EL display which has a perfect contrast ratio for the subjective assessment. The results of experiments showed that perceptual weighting improves the correlation between the SNR and MOS of the subjective assessment. It is recognized that the weighted LPSNR gives the best correlation.

Many subjective assessment methods for video quality are provided by ITU-T and ITU-R recommendations, but the differences among these methods have not been sufficiently studied. We compare five subjective assessment methods using four quantitative performance indices for both HD and QVGA resolution video. We compare the Double-Stimulus Continuous Quality-Scale (DSCQS), Double-Stimulus Impairment Scale (DSIS), Absolute Category Rating method (ACR), and ACR with Hidden Reference (ACR-HR) as common subjective assessment methods for HD and QVGA resolution videos. Furthermore, we added ACR with an 11-grade scale (ACR11) for the HD test and Subjective Assessment of Multimedia Video Quality (SAMVIQ) for the QVGA test for quality scale variations. The performance indices are correlation coefficients, rank correlation coefficients, statistical reliability, and assessment time. For statistical reliability, we propose a performance index for comparing different quality scale tests. The results of the performance comparison showed that the correlation coefficients and rank correlation coefficients of the mean opinion scores between pairs of methods were high for both HD and QVGA tests. As for statistical reliability provided by the proposed index, DSIS of HD and ACR of QVGA outperformed the other methods. Moreover, ACR, ACR-HR, and ACR11 were the most efficient subjective quality assessment methods from the viewpoint of assessment time.

Our research is focused on examining the video quality assessment model based on the MPEG-7 descriptor. Video quality is estimated by using several features based on the predicted frame quality such as average value, worst value, best value, standard deviation, and the predicted frame rate obtained from descriptor information. As a result, assessment of video quality can be conducted with a high prediction accuracy with correlation coefficient=0.94, standard deviation of error=0.24, maximum error=0.68 and outlier ratio=0.23.

We analyze subjective assessments by comparative evaluations of bulk data transmission by using two psychological methods (the method of successive categories and the constant method). From the results of the first experiment, the thresholds at which participants downloading a data file began to feel dissatisfaction with service degradation are 15.7 Mbps and 11.6 Mbps obtained by the two different methods when the throughput without the service degradation is approximately 22 Mbps. In the second experiment, we investigate the threshold of user satisfaction for various network environments. The threshold is 63% of the throughput of the user's usual network environment. Moreover, from the viewpoint of download time, users feel dissatisfaction with the quality when download time becomes 1.5 times longer. These values can be used to more effectively allocate network resources and thereby achieve higher service quality.

Providing mobile services that ensure user satisfaction is one of the most crucial issues for telecommunication carriers and service providers. Traditionally, user satisfaction with the service, i.e., the Quality of Experience (QoE), has been assessed in a laboratory by using elaborate network systems and customized terminals. However, reliable QoE for a target mobile service in the context of actual use cannot be obtained by laboratory experiment, since QoE can be affected by a variety of factors such as environmental conditions and the mental state of the user. This paper proposes a novel Web script-based field evaluation method designed to ascertain user satisfaction with mobile services. The proposed method has the following practical advantages. Since experimental conditions, especially communication conditions, can be simulated with a Web script, such as FlashLite, a subjective assessment can be conducted anywhere using the mobile terminal of the participant. Thus, QoE for a target mobile service in the field can easily be obtained.

Our research is focused on examining the Image Quality Assessment Model based on the MPEG-7 descriptor and the No Reference model. The model retrieves a reference image using image search and evaluate its subject score as a pseudo Reduced Reference model. The MPEG-7 descriptor was originally used for content retrieval, but we discovered that the MPEG-7 descriptor can also be used for image quality assessment. We examined the performance of the proposed model and the results revealed that this method has a higher performance rating than the SSIM.

Digital video encapsulates the time series of a frame (still) images, where overall video quality can be obtained by using the quality of each frame image and the temporal information between the frame image. Coding of video produces degradation of these two types of information. These degradations can be classified as spatial degradation (static degradation) of a frame images and temporal degradation between frame image (dynamic degradation). In the framework of video quality evaluation it is necessary to consider those degradations, because their contents are strongly interdependable and quantification is problematic for these degradations. Therefore, the development of an objective video quality assessment method for single video quality requires to investigate how much static degradation and dynamic degradation affect single video quality. In this research, single video quality was predicted highly accuratly by using frame quality as static degradation and frame rate information as dynamic degradation.

In this paper, we show that motion sharpening phenomenon can be explained as a form of visual masking for a special case where a video sequence is composed of alternate frames with different level of sharpness. A frame of higher sharpness behaves to mask the ambiguity of a subsequent frame of lower sharpness and hence preserves the perceptive quality of the whole sequence. Borrowing the mechanism for visual masking, we formulated a quantitative model for deriving the minimum spatial frequency conditions which preserves the subjective quality of the frames being masked. The quantitative model takes into account three fundamental properties of the video signals, namely the size of motion, average luminance and the power of each frequency components. The psychophysical responses towards the changes of these properties are obtained through subjective assessment tests using video sequences of simple geometrical patterns. Subjective experiments on natural video sequences show that more than 75% of viewers could make no distinction between the original sequence and the one processed using the quantitative model.

The Video Quality Experts Group (VQEG) is preparing a programme of subjective multimedia quality tests. The results from these tests will be used to evaluate the performance of competing objective multimedia quality metrics. The reliability of the subjective test data is of great importance for VQEG's task. This paper provides an overview of VQEG's multimedia ad-hoc group. The work of this group will require subjective tests to be performed by laboratories located in Europe, Asia and North America. For VQEG's multimedia work to be successful, the subjective assessment methodology must be precisely defined and produce reliable and repeatable subjective quality data. Although international standards covering multimedia quality assessment methods are in force, there remains some uncertainty regarding the most effective approach to assessing the subjective quality of multimedia. A review of existing methods is provided. Two experiments are presented investigating the suitability of alternative subjective assessment methods (single-stimulus ACR and SAMVIQ). The results of these experiments are discussed within the context of the VQEG multimedia testing programme.

This paper provides an overview of the new tendencies in the subjective assessment of the quality of video for Multimedia applications. New subjective assessment methods are here described together with the description of the new general approaches. Some motivations of these new approaches are also here provided.

Next generation codecs, benchmarked by the H.264/AVC standard, are providing substantial compression efficiency for the coding and transmission of video. Coupled with technologies offering larger transmission bandwidths over DSL, wireless and satellite networks, the capability of delivering high quality video services to the home is now a reality. The perceptual quality of the content delivered over communications networks will be crucial in ensuring a first-class customer experience. It is therefore important to assess the advantages and disadvantages of the optional features offered by next generation codecs. This paper describes a subjective assessment that was carried out to investigate the perceptual effects of switching the in loop de-blocking filter within the H.264/ AVC CODEC on or off. Although the filter is believed to substantially improve the perceptual quality of video, it has been suggested that in some cases negative perceptual effects can be produced. The H.264/AVC architecture allows de-blocking to be switched off in cases where there are limited processing resources or it is considered a negative perceptual effect may be introduced. This paper describes a study that examined the perceptual effects of de-blocking by employing a standardised subjective assessment methodology. The Absolute Category Rating (ACR) method was used to capture Difference Mean Opinion Scores (DMOS) for a range of video. Content was selected to span a wide and representative range of coding complexity. This content was then encoded at a variety of bit-rates to represent high, medium and low qualities. Results were used to examine the end-user perception of video quality when the de-blocking filter is switched on or off. The experimental design allowed the overall effects of the de-blocking filter to be examined and additionally the relationship between content and quality on the filter performance. The experiment found that the performance of the de-blocking filter was content-dependent. Results were used to discuss the advantages and disadvantages of in-loop de-blocking and there is an examination of content properties (e.g. spatial and temporal complexity) that influence the performance of de-blocking.

We propose the concept of an opinion model for interactive multimodal services and apply it to an audiovisual communication service. First, psychological factors of an audiovisual communication service were extracted by using the semantic differential (SD) technique and factor analysis. Forty subjects participated in subjective tests and performed point-to-point conversational tasks on a PC-based video phone that exhibited various network qualities. The subjects assessed those qualities on the basis of 25 pairs of adjectives. Two psychological factors, i.e., an aesthetic feeling and a feeling of activity, were extracted from the results. Then, quality impairment factors affecting these two psychological factors were analyzed. We found that the aesthetic feeling was affected by IP packet loss and video coding bit rate, and the feeling of activity depended on delay time, video packet loss, video coding bit rate, and video frame rate. Using this result, we formulated an opinion model derived from the relationships among quality impairment factors, psychological factors, and overall quality. The validation test results indicated that the estimation error of our model was almost equivalent to the statistical reliability of the subjective score.

This paper proposes a subjective model for estimating the quality of video streaming services with dynamic bit-rate control. In a subjective quality assessment test, we clarify users' perceptions of distributed video signals whose quality is time-variant due to dynamic bit-rate control. Using this result, we constructed an estimation model considering the following three characteristics: 1) the influence of the video section where quality degradation is large will strongly affect the overall quality, 2) the impression of a past quality weakens with the passage of time, and 3) the range of evaluation scores becomes wider when the time duration of an evaluation is longer. We found that the proposed model enables the accuracy of estimating overall subjective quality to be dramatically improved compared with that of a model that averages segmental quality. The estimation error of the proposed model is less than the statistical reliability of the subjective score even for verification data. We also show that our findings are applicable to QoS design/management issues for video streaming services with dynamic bit-rate control.

This paper assesses the media synchronization quality of recovery control schemes from asynchrony, which are referred to as reactive control schemes here, in terms of objective and subjective measures. We deal with four reactive control techniques: skipping, discarding, shortening and extension of output duration, and virtual-time contraction and expansion. We have carried out subjective and objective assessment of the media synchronization quality of nine schemes which consist of combinations of the four techniques. The paper makes a comparison of media synchronization quality among the schemes. It also clarifies the relations between the two kinds of quality measures.

In this paper, we describe an experimental evaluation of visual fatigue in a binocular disparity type 3-D display system. To evaluate this fatigue, we use a subjective assessment method and focus on mismatching between convergence and accommodation, which is a major weakness of binocular disparity 3-D displays. For this subjective assessment, we use a newly-developed binocular disparity 3-D display system with a compensation function for accommodation. Because this equipment only allowed us to compare the terms of the mismatching itself, the evaluation is more accurate than similar previous works.

Cell loss is one of the most important metrics of quality of service in ATM mobile communication systems. This loss can be suppressed by introducing buffer memories in the network, but that sacrifices delay. This paper proposes a lossless handover scheme for ATM mobile communication networks that can suppress delay fluctuations, and presents a subjective evaluation of MPEG2 images with various buffer memory sizes.

This paper presents results of subjective assessment of the media synchronization quality in the virtual-time rendering (VTR) media synchronization algorithm. For the assessment, stored voice and video streams were transmitted as two separate transport streams from a source to a destination on various traffic conditions in an experimental system. At the destination, they were output after synchronization control. We subjectively assessed the quality of media synchronization in a systematic way. This paper examines the effects of the difference between methods of recovery from asynchrony on the media synchronization quality. The paper also clarifies the relationships between the subjective and objective performance measures. Furthermore, it examines the effect of the difference in scene between media streams and that of the modification of the target output time on the media synchronization quality.