José Vinícius de Miranda Cardoso

Objective estimation of 3D video quality: A disparity-based weighting strategy

This paper presents new results on the objective evaluation of stereoscopic video quality. A balance between the scores provided by classical objective algorithms and the disparity information of the reference video is found. The performance of the proposed technique was verified using statistical metrics (correlation coefficients and root mean square error) that compare the scores provided by the objective algorithms and the subjective results provided by the NAMA3DS1-COSPAD1 stereoscopic video quality database. The obtained results suggest a significant improvement on the performance of the objective algorithms for the proposed technique.

Effect of visual attention areas on the objective video quality assessment

The objective assessment of video quality is an important area of research for the validation of video systems, and new algorithms are always in demand. Experiments indicate that the inclusion of characteristics of the human visual system into the objective metric, such as visual attention, improves the evaluation. This paper presents a new approach to evaluate the video quality based on an estimate of the local visual attention, using the structural similarity index. This approach is compared with three classical objective metrics: PSNR, SSIM and MS-SSIM, by means of the Pearson linear and Spearman rank-order correlation coefficients. The videos are submitted to several types of distortions, such as blocking, blurring and salt & pepper noise. The results indicate that the proposed approach presents good correlation with the subjective scores, for videos that contain blurring and blocking degradations.

Performance of the objective video quality metrics with perceptual weighting considering first and second order differential operators

Objective video quality assessment is important to validate the performance of applications in video communications systems. The research on visual attention and gradient-inspired metrics improves the performance of the video quality evaluation. This paper investigates the use of first and second order differential operators as visual attention estimators. The edge information, computed by differential operators, is an important factor of visual attention. The performance of the proposed models are compared with the objective metrics, PSNR, SSIM and GSSIM, by means of the Pearson correlation coefficient, considering the blurring, blocking, salt and pepper and Gaussian noise distortions. The results suggest that for blurring, blocking and salt and pepper, the combination of objective metrics with first order operators provides a significant improvement, especially for the Sobel operator.

Temporal analysis and perceptual weighting for objective video quality measurement

Video quality measurement is an important factor to establish the quality of video communication and processing systems, such as broadcasting and mobile television, since they need to monitor broadcasting quality to compute optimal parameters that ensure a satisfactory quality level. The objective video quality assessment is a quick and low cost alternative when compared with the subjective evaluations. This paper presents a novel objective video quality algorithm that combines temporal analysis and the perceptual weighting technique. The proposed algorithm was validated using the correlation between objective measurements and the subjective scores provided by the LIVE Video Quality Database, considering the following conditions: H.264 and MPEG-2 encoding and transmission of H.264 bit-streams over IP and wireless networks. The results demonstrate that the proposed algorithm is a competitive alternative when compared with classical objective algorithms, such as MOVIE.

Disparity weighting applied to full-reference and no reference stereoscopic image quality assessment

This paper presents an evaluation of performance of the disparity weighting technique when it is applied to stereoscopic image quality assessment in full reference and no-reference scenarios. The correlation coefficients between the subjective scores in the LIVE 3D Database and the predicted scores indicate a significant increase in the performance.

Design of Objective Video Quality Metrics Using Spatial and Temporal Informations

Digital videos are subject to several types of distortions, which may occur during the processes of acquisition, processing, compression, storage and transmission of videos, resulting in loss of visual quality. Video quality assessment is important to set system parameters and propose the reduction of degradation, to improve the systems quality. The most appropriate way to assess the visual quality of a video sequence is subjective assessment. This study proposes new metrics for assessment of videos. The proposed metrics that uses spatial and temporal information to evaluate videos are more closely to the subjective assessment. For the evaluation of videos the BD-TPW-SSIM and TP-VQI metric obtained the best result for wireless degradation. For MPEG-2 encoded videos, T-PW-SSIM e T-MOVIE was the best, and IP systems the metric with the best result was the TPW-SSIM. Finally, the metric T-VimSSIM was the best for H.264 encoding.

New closed-form expressions for SNR estimates of Nakagami fading channels by the method of moments

Method of moments has been a parameter estimation technique appropriate to calculate signal-to-noise ratio (SNR) estimates in fading channel models in which an optimal technique like maximum likelihood estimation is not mathematically tractable. In this article, the ratio of the second moment squared to the fourth moment of the received signal envelope is considered to calculate an exact expression for the SNR estimate in Nakagami-m fading channel for M-QAM and

An approximate exponentiated Weibull joint envelope-phase distribution

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