The subjective method; page 1 of 3

Better quality assessment is obtained when processed material is presented to humans. The procedure is:

1. Prepare testing room and equipment according to the BT.500 and BT.814 Recommendations (room illumination, display parameters, maximum observation angle and so on).

2. Prepare decoded materials and store them in random order. (Some hints will be given later.) Divide the material into sessions not longer than 30 minutes. People are usually tired after half an hour of testing. Moreover, they often get used to shown artifacts, so opinions given for the materials at the end of to long testing phase will be higher comparing for the shown earlier (even if they was really worse).

3. Take groups of 15 people. They should be non-expert, in the sense that they are not directly concerned with picture quality as part of their normal work, and are not experienced assessors. All people are more sensitive to the problems they work with; comparing to the "average" final user. Moreover, experts usually work with some - not all - processing methods. In consequence, they will be more sensitive to some specific errors, thus it is hard to consider their opinion to be representative.