Insertion of Impairments in Test Video Sequences for Quality Assessment Based on Psychovisual Characteristics

Abstract

-Assessing video quality is a complex task. While most pixel-based metrics do not present enough correlation between objective and subjective results, algorithms need to correspond to human perception when analyzing quality in a video sequence. For analyzing the perceived quality derived from concrete video artifacts in determined region of interest we present a novel methodology for generating test sequences which allow the analysis of impact of each individual distortion. Through results obtained after subjective assessment it is possible to create psychovisual models based on weighting pixels belonging to different regions of interest distributed by color, position, motion or content. Interesting results are obtained in subjective assessment which demonstrates the necessity of new metrics adapted to human visual system.

Definition of masks related to psychovisual features for Video Quality Assessment

“…Impairment is produced over motion, level of detail, pixel location and the appearance of human faces. In [9] the characteristics of this sequences are collected for each of the degradation when applying the distorted image only to one on the six regions of interest for each phenomena (details or spatial entropy; motion or temporal entropy; center, lateral or corner position and faces presence), conserving the rest of the picture sharped. For each of these six phenomena the inverse version was also developed, i.e.…”

“…After analyzing the subjective results in [9], coefficients were assigned to the four different masks related to each of the image characteristic selected. The values were defined ordering the level of importance derived from observers' opinions.…”

Obtención y adaptación de mapas de profundidad en vídeo estereoscópico: influencia en la codificación y el comportamiento visual tridimensional en tiempo real

“…Para ello se necesita conocer la satisfacción del consumidor relacionada con una serie de parámetros que puedan ser medibles. Es habitual utilizar secuencias de vídeo a las que se somete a algún proceso de degradación para poder utilizarlas como banco de pruebas y conocer los efectos de los parámetros modificados en la calidad percibida por el observador [36]. En la mayoría de ocasiones, no es posible asumir la relación directa entre una medida objetiva y la calidad subjetiva.…”