Perceived sharpness in moving images

\u3cp\u3eTwo investigations were set up into the dependence of the human sharpness impression in complex scenes on velocity and resolution. Sequences, in which a portrait was moving horizontally at a constant speed, were presented on a high-resolution monitor (velocities between 0.5 and 35 deg/s). Both a maximum resolution version and bandwidth-reduced versions were presented. Subjects assessed the (subjective) sharpness of the stimuli on a categorical scale. The results show that for the maximum resolution images, there is hardly any change in perceived sharpness as a function of velocity. Furthermore, for the low resolution images, we find an increase in sharpness with velocity, which implies that the perceived sharpness range is compressed at those velocities.\u3c/p\u3

Subjective image quality as a function of viewing distance, resolution and picture size

This paper describes two experiments concerning the subjective quality of complex scenes. Slide projections were used as stimuli and they were varied in viewing distance, resolution and picture size. The subjective quality Was judged by a group of twenty subjects by means of categorical scaling. The results of the experiments show that the (angular) resolution expressed in periods per degree and the picture angle spanned by the display, each influence the quality independently. Subjective quality increases with resolution, but saturates at a resolution (6 dB cut-off frequency) of approximately 25 periods per degree. There is also a linear relationship between the subjective quality and the logarithm of the picture angle. In the discussion, these results are compared with those of a number of experiments known from the literature. The results are also interpreted in terms of consequences for High-Definition TV

Evaluation of PALplus proposals

Discusses the evaluations made within the framework of the PALplus group to assess both the PALplus quality and the compatible quality of several candidate algorithms, based on simulations. Since the detailed information is confidential to the members of the PALplus group, the paper focuses on the methodology and on the implementatio

Pointing in entertainment-oriented environments : appreciation versus performance

Multimedia :Applications for consumer entertainment of I en employ a point-and-select interaction style, borrowed from more task-oriented computer applications. The environment afuse and the pointing devices involved are so different, however, that a higher importance should be attributed to the users' appreciation of the pointing device than to its efficiency or any other objective performance measure. We set up an experiment to investigate how appreciation and performance measures relate. The experiment involved six different input devices, two CD-i litles and 16 subjects making both voluntary and prescribed cursor control movements. For the mouse-like pointing devices we obtained a Fins' Law-like dependence on target width and target distance. This was, however, not replicated for any of the other input devices, mainly owing to a positive influence of cursor constraints. Concerning the relation of the performance measures with the users' appreciation, we found that neither time-to-target nor relative-path-length on its own is a reliable indicator of the users' appreciation. Together, however, they might explain the appreciation scores to a considerable extent