Forming valid scales for subjective video quality measurement based on a hybrid qualitative/quantitative methodology

Abstract

This study presents a methodology of forming contextually valid scales for subjective video quality measurement. Any single value of quality e.g. Mean Opinion Score (MOS) can have multiple underlying causes. Hence this kind of a quality measure is not enough for example, in describing the performance of a video capturing device. By applying Interpretation Based Quality (IBQ) method as a qualitative/quantitative approach we have collected attributes familiar to the end user and that are extracted directly from the material offered by the observers' comments. Based on these findings we formed contextually valid assessment scales from the typically used quality attributes. A large set of data was collected from 138 observers to generate the video quality vocabulary. Video material was shot by three types of video cameras: Digital video cameras (4), digital still cameras (9) and mobile phone cameras (9). From the quality vocabulary, we formed 8 unipolar 11-point scales to get better insight of video quality. Viewing conditions were adjusted to meet the ITU-T Rec. P.910 requirements. It is suggested that the applied qualitative/quantitative approach is especially efficient for finding image quality differences in video material where the quality variations are multidimensional in nature and especially when image quality is rather high.

Objective Video Quality Assessment Methods: A Classification, Review, and Performance Comparison

“…The prominent subjective tests used from ITU-R Rec. BT.500-11 [14] and ITU-T Rec.P.910 [16] [43]. The DSCQS and DSIS II scales have been compared in [44], revealing that the DSCQS scale is robust with respect to the level of video impairment, while the DSIS II scale exhibited high sensitivity to the impairment level.…”

Evaluating the multivariate visual quality performance of image-processing components

“…The approach has been used in defining the subjective quality dimensions related to sharpness changes that mimic the camera lenses , the comparison of digital still [Radun et al 2006] and video cameras [Virtanen et al 2008;Radun et al 2007], print quality with natural image contents [Nyman et al 2005], and stereoscopic image quality Shibata et al 2008]. …”

Visual Quality Method in Assessing Landscape Characteristics: Case Study of Bozcaada Island

“…The IBQ approach can complement psychometric approaches and objective measurements by defining the subjective meaning of image quality attributes and characteristics; in other words, it reveals how important they are for the overall perceived quality. The method has been used in defining subjective quality dimensions related to sharpness changes that mimic the camera lenses 10 , the comparison of digital still 9 and video cameras 39 , print quality with natural image contents 38 , and stereoscopic 3D image quality 40 .…”