Yöntem

Neste tipo de avalia¸c˜ao subjetiva, cada observador i faz seu julgamento a respeito da cenaseq¨uˆencia k, sob a condi¸c˜ao de teste j, repetindo r vezes. A nota m´edia para a cena k pode ser calculada usando:

uk = 1 N · J · R· N X i=1 J X j=1 R X r=1 ui,j,k,r (B.1)

Onde: ui,j,k,r´e a nota dada pelo observador i, sob condi¸c˜ao j, da cena k, repeti¸c˜ao

r. N ´e o n´umero de observadores. J ´e a quantidade total de condi¸c˜oes de teste aplicadas. R ´e o n´umero de vezes que a cena foi mostrada.

O ´ındice uk´e usualmente referido como MOS, e representa a qualidade m´edia

subjetiva. No m´etodo DSCQS, este ´ındice ´e calculado para cada cena do par (original e processada), e a diferen¸ca entre as duas ´e referida como DMOS. O VQEG utilizou um total de 297 pessoas em 8 diferentes laborat´orios reconhecidos em todo o mundo para avaliar os 320 pares de cenas na fase I de seus trabalhos. A Tabela 14 mostra a quantidade de avaliadores que cada laborat´orio utilizou em cada grupo de cenas avaliadas.

Tabela 14: Quantidade de avaliadores nos laborat´orios para cada conjunto de cenas

Laborat´orio Padr˜ao N Padr˜ao N Padr˜ao M Padr˜ao M

low quality high quality low quality High quality

Berkom (Alemanha) 18 18 CRC (Canad´a) 27 21 FUB (It´alia) 18 17 NHK (Jap˜ao) 17 17 CCETT (Fran¸ca) 18 17 CSELT (It´alia) 18 18 DCITA (Austr´alia) 19 18 RAI (It´alia) 18 18 TOTAL 73 71 80 73

Os conjuntos de notas obtido por cada laborat´orio foram comparados entre si. A correla¸c˜ao entre as avalia¸c˜oes feitas pelos laborat´orios est˜ao mostradas nas Tabelas 15 e 16.

Na Tabela 17 as colunas representam as cenas originais (SRC) e as linhas representam cada uma das distor¸c˜oes inseridas (HRC). Os valores de cada c´elula representam a m´edia de todas as avalia¸c˜oes subjetivas feitas sobre o par de cenas indicado pela linha e coluna.

Tabela 15: Correla¸c˜ao entre os resultados de avalia¸c˜ao dos laborat´orios para o conjunto de cenas padr˜ao M Low Quality

Laborat´orio Berkom CRC FUB NHK

Berkon 1,000 0,747 0,913 0,933

CRC 0,747 1,000 0,807 0,727

FUB 0,913 0,807 1,000 0,935

NHK 0,933 0,727 0,935 1,000

Tabela 16: Correla¸c˜ao entre os resultados de avalia¸c˜ao dos laborat´orios para o conjunto de cenas padr˜ao M High Quality

Laborat´orio Berkom CRC FUB NHK

Berkon 1,000 0,790 0,854 0,831

CRC 0,790 1,000 0,818 0,837

FUB 0,854 0,818 1,000 0,880

NHK 0,831 0,837 0,880 1,000

Tabela 17: Resultados das avalia¸c˜oes subjetivas sobre cada par de cenas

SCR 13 14 15 16 17 18 19 20 21 22 HRC 1 12,8 25,5 33,9 32,2 07,6 29,6 19,9 35,7 29,6 26,9 2 05,7 02,2 17,8 02,3 02,0 06,0 04,4 -00,5 06,4 04,3 3 04,8 11,9 22,1 03,9 04,1 13,6 02,6 15,0 06,0 09,3 4 11,1 06,3 24,5 04,6 05,1 11,8 07,5 02,4 09,4 07,7 5 11,1 08,0 21,4 03,9 10,7 12,6 11,4 04,3 -00,7 08,7 6 10,4 12,9 32,3 04,9 03,5 06,6 10,7 02,1 01,5 06,8 7 08,1 04,2 13,4 04,4 07,3 02,9 02,7 04,9 -03,0 03,5 8 13,8 19,2 34,7 02,2 06,9 08,3 11,8 02,4 02,2 07,7 9 24,0 07,1 23,5 06,5 18,3 08,8 25,0 02,6 00,2 07,9 10 16,8 05,8 18,6 19,5 13,6 07,6 09,8 05,4 -01,1 07,5 11 38,7 17,8 28,6 14,0 23,4 03,5 50,9 04,4 12,2 12,8 12 21,6 16,5 19,4 06,2 10,6 06,2 28,6 08,8 08,1 12,4 13 32,2 26,4 55,3 13,7 50,2 20,8 41,2 11,2 03,3 25,2 14 40,0 23,6 31,6 07,7 28,8 15,5 42,5 04,6 02,5 26,3 15 51,9 40,6 52,7 30,6 43,7 38,5 45,6 22,9 25,7 41,3 16 35,6 38,3 50,0 22,8 28,3 33,2 24,9 25,7 15,3 34,9

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