**2. Quality of immersive media**

The word quality is widely used in the most diverse fields. However, the agreement on the idea of quality is very hard and depends on several aspects: the application, the historical period, or even the background of each person. The concept of quality is something everybody understands but can hardly define.

Going back to ancient times, Aristotle classified every object of human apprehension into 10 categories: Substance, Quantity, Quality, Relation, Place, Time, Position, State, Action, Affection. Qualities are hylomorphically–formal attributes, such as "white" or "grammatical". Always remaining in antiquity, Quality in ancient Egypt was "a sign of perfection."

Nowadays, scientists have tried to better define this concept to be able to measure it. Among others, relevant ones are:


To summarizing, quality is a relative concept: it can rather be expressed as a degree of quality. We can agree with this statement: "the quality of something can be determined by comparing a set of inherent characteristics with a set of requirements. We will have high quality if characteristics meet requirements, and low quality, if characteristics do not meet all requirements. Nowadays, the research is devoted to the QoE evaluation, that is "The degree of delight or annoyance of the user of an application or service. It results from the fulfillment of his or her expectations for the utility and / or enjoyment of the application or service in the light of the user's personality and current state" [3].
