?Rec.? ITU-R? BT.500-11? 1
RECOMMENDATION? ITU-R? BT.500-11
Methodology for the subjective assessment of the
quality of television pictures
(Question ITU-R 211/11)
(1974-1978-1982-1986-1990-1992-1994-1995-1998-1998-2000-2002)

The ITU Radiocommunication Assembly,
considering
a)? that a large amount of information has been collected about the methods used in various
laboratories for the assessment of picture quality;
b)? that examination of these methods shows that there exists a considerable measure of
agreement between the different laboratories about a number of aspects of the tests;
c)? that the adoption of standardized methods is of importance in the exchange of information
between various laboratories;
d)? that routine or operational assessments of picture quality and/or impairments using a
five-grade quality and impairment scale made during routine or special operations by certain
supervisory engineers, can also make some use of certain aspects of the methods recommended for
laboratory assessments;
e)? that the introduction of new kinds of television signal processing such as digital coding and
bit-rate reduction, new kinds of television signals using time-multiplexed components and, possibly,
new services such as enhanced television and HDTV may require changes in the methods of
making subjective assessments;
f)? that the introduction of such processing, signals and services, will increase the likelihood
that the performance of each section of the signal chain will be conditioned by processes carried out
in previous parts of the chain,
recommends
1? that the general methods of test, the grading scales and the viewing conditions for the
assessment of picture quality, described in the following Annexes should be used for laboratory
experiments and whenever possible for operational assessments;
2? that, in the near future and notwithstanding the existence of alternative methods and the
development of new methods, those described in ? 4 and 5 of Annex 1 to this Recommendation
should be used when possible; and
3? that, in view of the importance of establishing the basis of subjective assessments, the
fullest descriptions possible of test configurations, test materials, observers, and methods should be
provided in all test reports;
4? that, in order to facilitate the exchange of information between different laboratories, the
collected data should be processed in accordance with the statistical techniques detailed in Annex 2
to this Recommendation.