ITU-T J.340-2010 Reference algorithm for computing peak signal to noise ratio of a processed video sequence with compensation for constant spatial shifts@ constant temporal shift@ and constant luminance gain and offset (Study Group 9)
ITU-T - International Telecommunication Union/ITU Telcommunication Sector
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ITU-T J.340-2010
Scope
Peak Signal to Noise Ratio (PSNR) is a useful benchmark for evaluating performance improvements of new objective perceptual video quality metrics. For example@ PSNR has been used as a benchmark for both the Multimedia (MM) and Reduced Reference Television (RRTV) test programs recently completed by the Video Quality Experts Group (VQEG). Since the calculation of PSNR is highly dependent upon proper estimation of spatial alignment@ temporal alignment@ gain@ and level offset between the processed video sequence and the original video sequence@ the method of measurement for PSNR should ideally include a method for performing these calibration procedures. This PSNR calculation method in this Recommendation has the advantage of automatically determining the highest possible PSNR value for a given video sequence over the range of spatial and temporal shifts. Only one temporal shift is allowed for all frames in the entire processed video sequence (i.e.@ constant delay). This Recommendation defines a Full Reference (FR) algorithm for computing both the calibration and PSNR estimations for a processed video sequence: Peak Signal to Noise Ratio with Compensation for Constant Spatial Shifts@ Constant Temporal Shift@ and Constant Luminance Gain Offset (PSNRconst). Since the PSNRconst algorithm only examines the Y luminance channel (as defined by ITU-R Recommendation BT.601-6) distortions in the CB and CR chrominance channels will not be detected by the algorithm of this Recommendation. The intent of this Recommendation is to define and facilitate a standardized PSNR metric for use by industry and standards organizations. Reference code and test vectors have been included to assure accurate and consistent implementation of this PSNRconst metric. The intention of this PSNRconst metric is to fully calibrate the video and then calculate PSNR on the luminance plane only. For these purposes@ calibration consist of selecting the valid video region spatially (e.g.@ discarding the overscan region) and then removing from the entire video sequence a constant temporal shift (delay or advance)@ a constant spatial shift (vertically and horizontally)@ and a constant luminance gain offset. Common applications of the PSNRconst algorithm include: ? A reference benchmark for evaluating the effectiveness of perceptual quality metrics. ? A FR Quality of Service metric (QoS) for video transmission systems. It should be noted that the use of this calibration method will result in the best possible PSNRconst value for a video sequence with constant delay. This value may differ from PSNRconst obtained with perfectly calibrated video. Degradations due to gain are removed by this method. If higher PSNRconst is obtained using an alternative calibration method then this alternative calibration method can be used@ although differences are expected to be small. It is noted that this Recommendation considers only integer-pixel shifts. It should be noted that this PSNRconst algorithm will not detect as an impairment a constant spatial shift@ a constant luminance gain@ a constant luminance offset@ or a constant temporal shift.
ITU-T J.340-2010 history
2010ITU-T J.340-2010 Reference algorithm for computing peak signal to noise ratio of a processed video sequence with compensation for constant spatial shifts@ constant temporal shift@ and constant luminance gain and offset (Study Group 9)