Definition and validation of methods for the subjective assessment of visual telephone picture quality

Experimental methods have been developed particularly for the subjeelive evaluation of picture telephone systems. The viewing conditions deviate to some extent from earlier recommendations, and the experimental procedures comprise some new features. The methods have been validaled in a test with participation from laboratories in five countries. The results obtained from different laboratorles are generally in good agreement. Results obtained by different methods within a Iabaratory are very similar. The tests prove that alternative experimental methods can be applied for the subjeelive assessment of picture quality with the same result.