Development of judder artifacts assessment method and its application to dynamic frame-rate control

Abstract

When moving objects are presented on a hold-type display with a low frame rate (LFR), temporal aliasing, especially judder artifacts, can be perceived by a viewer. In this work, a new metric to measure judder artifacts of video sequence is proposed. In addition, to consider both computational complexity and perceptual quality, dynamic frame-rate control is proposed using judder artifacts measurement of video sequence.

In judder artifacts measurement part, we propose a new metric to measure judder artifacts of video sequences. Judder artifacts appear as non-smooth motions in hold-type displays when the frame rate is low and object motion is fast. To analyze judder artifacts in video sequences, the proposed judder metric is defined by analyzing the effects and cross-relations of judder features in the video sequences. The judder features include spatial features of image gradients and temporal features of motion vectors and the frame rate. In addition, sensitivity of the human visual system (HVS) is considered to determine the perceptual judder artifacts because it has special characteristics of sensitivity to image brightness and contrast. Therefore, a sensitivity map of the HVS is used to mask judder artifacts. Experimental results demonstrate that the proposed judder metric is highly correlated with the subjective assessment results.

In the dynamic frame-rate control part, we propose a dynamic frame-rate control method, which can adaptively adjust the frame rates while minimizing judder artifacts. The proposed method measures the degree of judder artifacts, called the judder score, and adjusts frame rate according to the judder score. To improve the measurement accuracy of judder artifacts, content-adaptive pooling is used by analyzing the judder features. In order to set a criterion for adjusting frame rate, we determine a perceptual threshold of judder artifacts through subjective assessment. The proposed method is applied to the frame rate up-conversion (FRUC), and the experimental results show that the proposed method produces dynamic frame rate that minimizes judder artifacts and controls the frame rates more effectively than the previous methods.