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A D V A N C E D
P E R C E P T U A L
E V A L U A T I O N
O F
V I D E O
Q U A L I T Y
6.4 Performance of PEVQ
Currently PEVQ is largely time consuming because of its very complex not optimized calculations. OPTICOM
expects that within a very short time after this first release, the algorithm will be optimized to run at least in real-
time on up-to-date PC systems.
6.5 KPIs Obtained from PEVQ
The intention of this subchapter is to give a short overview of PEVQ's key performance indicators (KPIs). PEVQ's
KPIs are a number of extra parameters beside the overall quality of the video stream, which are partly also
available at the output of the algorithm. They allow for a detailed cause analysis, if the quality of the measured
video sequence is not satisfactory.
Note: In this first version of PEVQ only a few KPIs are presented. If you have e.g. suggestions on which parameters
you are interested in or if you need further information towards this product please feel free to contact us
info@opticom.de
or visit our web site on www.opticom.de.
6.5.1 PEVQ Score
The PEVQ Score is the most important result and specifies the video quality on a MOS scale. The scale ranges
from 1 for very bad quality to 5 for excellent quality. Please note that unlike the MOS scale, the PEVQ Score is not
limited to the lower end of 1.0. When extreme artifacts occur scores smaller than 1.0 may be obtained. This
behaviour is by design in order to allow for the assessment of severely distorted video sequences, whose quality is
below the worst case of the MOS scale. The PEVQ Score is based on a multitude of perceptually motivated
parameters. Most of these parameters are available internally only and are not presented as KPIs since their
meaning to human beings is very limited.
6.5.2 Delay
The delay information is provided in the form of a buffer containing the delay for each test signal frame with
respect to the reference signal.
6.5.3 Brightness
The brightness of the reference and the impaired signal.
6.5.4 Contrast
The contrast of the reference and the impaired signal.
6.5.5 PSNR
To allow for a coarse analysis of the distortions in different domains the peak signal to noise ratio (PSNR) is
provided for the Y (luminance), Cb and Cr (chrominance) components separately.
6.5.6 Distortion Indicators
For a more detailed analysis the perceptual level of differences in the luminance, chrominance and temporal
domain are provided.
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