Hong Ren Wu
The discussions in previous chapters have highlighted an increasing emphasis on Quality of Experience (QoE)  compared with Quality of Service (QoS)  in audio-visual communication, broadcasting and entertainment applications, which signals a transition from technology-driven services to user-centric (or perceived) quality-assured services . QoE as defined by ITU SG 121 is application or service specific and influenced by user expectations and context , and therefore necessitates assessments of perceived service quality and/or utility (or usefulness) of the service . Subjective assessment and evaluation of the service are imperative to establish the ground truth for objective assessment and measures which aid in the design/optimization of devices, products, systems, and services in either the online or offline mode . Assessment or prediction of QoE in multimedia services will have to take account of at least three major factors, including audio signal quality perception, visual signal quality perception, and interaction or integration of the perceived audio and visual signal quality [5–7], considering coding, transmission, and application/service conditions [3, 6, 8, 9]. This chapter focuses on the issues underpinning the theoretical frameworks/models and methodologies for QoE subjective and objective evaluation of visual signal communication services.
Subjective picture quality ...