Rec. Itu-r bt. 1683




Yüklə 1.34 Mb.
səhifə1/26
tarix16.04.2016
ölçüsü1.34 Mb.
  1   2   3   4   5   6   7   8   9   ...   26

Rec. ITU-R BT.1683

RECOMMENDATION ITU R BT.1683

Objective perceptual video quality measurement techniques for standard definition digital broadcast television in the presence of a full reference

(Question ITU R 44/6)

(2004)

The ITU Radiocommunication Assembly,



considering

a) that the ability to measure automatically the quality of broadcast video has long been recognized as a valuable asset to the industry;

b) that conventional objective methods are no longer fully adequate for measuring the perceived video quality of digital video systems using compression;

c) that objective measurement of perceived video quality will complement conventional objective test methods;

d) that current formal subjective assessment methods are time-consuming and expensive and generally not suited for operational conditions;

e) that objective measurement of perceived video quality may usefully complement subjective assessment methods,



recommends

1 that the guidelines, scope and limitations given in Annex 1 be used in the application of the objective video quality models found in Annexes 2 5;

2 that the objective video quality models given in Annexes 2 5 be used for objective measurement of perceived video quality.

Annex 1

Summary


This Recommendation specifies methods for estimating the perceived video quality of a one-way video transmission system. This Recommendation applies to baseband signals. The estimation methods in this Recommendation are applicable to:

codec evaluation, specification, and acceptance testing;

– potentially real-time, in-service quality monitoring at the source;

– remote destination quality monitoring when a copy of the source is available;

– quality measurement of a storage or transmission system that utilizes video compression and decompression techniques, either a single pass or a concatenation of such techniques.

Introduction


The ability to measure automatically the quality of broadcast video has long been recognized as a valuable asset to the industry. The broadcast industry requires such tools to replace or supplement costly and time-consuming subjective quality testing. Traditionally, objective quality measurement has been obtained by calculating peak signal-to-noise ratios (PSNRs). Although a useful indicator

of quality, PSNR has been shown to be a less than satisfactory representation of perceptual quality. To overcome the limitations associated with PSNR, research has been directed towards defining algorithms that can measure the perceptual quality of broadcast video. Such objective perceptual quality measurement tools may be applied to testing the performance of a broadcast network, as equipment procurement aids and in the development of new broadcast video coding techniques. In recent years, significant work has been dedicated to the development of reliable and accurate tools that can be used to objectively measure the perceptual quality of broadcast video. This Recommendation defines objective computational models that have been shown to be superior to PSNR as automatic measurement tools for assessing the quality of broadcast video. The models were tested on 525-line and 625-line material conforming to Recommendation ITU R BT.601, which was characteristic of secondary distribution of digitally encoded television quality video.

The performance of the perceptual quality models was assessed through two parallel evaluations of the test video material1. In the first evaluation, a standard subjective method, the double stimulus continuous quality scale (DSCQS) method, was used to obtain subjective ratings of quality of video material by panels of human observers (Recommentdation ITU-R BT.500 – Methodology for the subjective assessment of the quality of television pictures). In the second evaluation, objective ratings were obtained by the objective computational models. For each model, several metrics were computed to measure the accuracy and consistency with which the objective ratings predicted the subjective ratings. Three independent laboratories conducted the subjective evaluation portion of the test. Two laboratories, Communications Research Center (CRC, Canada) and Verizon (United States of America), performed the test with 525/60 Hz sequences and a third lab, Fondazione Ugo Bordoni (FUB, Italy), performed the test with 625/50 Hz sequences. Several laboratories “proponents” produced objective computational models of the video quality of the same video sequences tested with human observers by CRC, Verizon and FUB. The results of the tests are given in Appendix 1.

This Recommendation includes the objective computational models shown in Table 1.

TABLE 1


Model
number


Name

Video Quality Experts Group (VQEG)
proponent


Country

Annex

1

British Telecom

D

United Kingdom

2

2

Yonsei University/Radio Research Laboratory/SK Telecom

E

Korea (Rep. of)

3

3

Center for Telecommunications Research and Development (CPqD)

F

Brazil

4

4

National Telecommunications and Information Administration/Institute for Telecommunication Science (NTIA/ITS)

H

United States of America

5

A complete description of the above four objective computational models is provided in Annexes 2 5.

Existing video quality test equipment can be used until new test equipment implementing any of the four above models is readily available.

For any model to be considered for inclusion in the normative section of this Recommendation in the future, the model must be verified by an open independent body (such as VQEG) which will do the technical evaluation within the guidelines and performance criteria set out by Radiocommunication Study Group 6. The intention of Radiocommunication Study Group 6 is to eventually recommend only one normative full reference method.


  1   2   3   4   5   6   7   8   9   ...   26


Verilənlər bazası müəlliflik hüququ ilə müdafiə olunur ©azrefs.org 2016
rəhbərliyinə müraciət

    Ana səhifə