This paper tries to examine the results of a subjective evaluation experiment, made by means of the new Expert Viewing Protocol, recently approved by ITU-R Study Group 6 [1]. The EVP subjective test was designed and performed to compare different HDR coding technologies during an MPEG meeting (San Diego, CA, February 2016) [2]. Thanks to the wide and enthusiastic participation of the MPEG experts to the subjective evaluation experiment, it was possible to collect data from a total of sixteen viewers; this allowed to perform a sort of “validation” of the performance of the EVP. The ITU-R Recommendation states that tests with nine viewers is sufficient to get acceptable results from an EVP experiment. In our case, having data from 16 viewers, it was possible to compute the MOS and the Confidence Interval data as if it were a standard subjective assessment experiment (which typically requires more viewers). This allowed a sort of “validation” of the results obtained using results from 9 experts only vs. the results obtained using the data from the 16 viewers. The analysis of the raw data showed a rather good conversion of the EVP results towards the results obtained using the full viewers’ data set. The results of the EVP evaluation of MPEG HDR content was described in details in a previous paper [3], to which we defer for details on the EVP protocol procedure and rules. This paper instead tries to answer to a demand for further clarification on the “context” and “limitations of use” of the EVP when performed in alternative to a formal subjective experiment trial.

Date Published: 27 September 2016
PDF: 5 pages
Proc. SPIE 9971, Applications of Digital Image Processing XXXIX, 99710I (27 September 2016);

Published in SPIE Proceedings Vol. 9971:
Applications of Digital Image Processing XXXIX
Andrew G. Tescher, Editor(s)