A wristband-type PPG heart rate sensor capable of overcoming motion artifacts in daily activity and detecting heart rate variability has been developed together with a motion artifact cancellation framework. In this work, a motion artifact model in daily life was derived and motion artifacts caused by activity of arm, finger, and wrist were cancelled significantly. Highly reliable instant heart rate detection with high noiseresistance was achieved from noise-reduced pulse signals based on peak-detection and autocorrelation methods. The wristband-type PPG heart rate sensor with our motion artifact cancellation framework was compared with ECG instant heart rate measurement in both laboratory and office environments. In a laboratory environment, mean reliability (percentage of time within 10% error relative to ECG instant heart rate) was 86.5% and the one-day pulse-accuracy achievement rate based on time use data of body motions in daily life was 88.1% or approximately 21 hours. Our device and motion artifact cancellation framework enable continuous heart rate variability monitoring in daily life and could be applied to heart rate variability analysis and emotion recognition.
This paper considers the architecture and the effectiveness of new algorithms that control the subjective depth on 3-D displays by modulating the contrast of stereoscopic pictures on the basis of a quantified monocular depth cue. First, a psychophysical experiment to quantify the relationship between contrast and subjective depth was conducted. This experimental result shows that the higher the contrast, the nearer the object will be perceived, corresponding to the qualitative relationship. Second, this result was applied to image-processing algorithms that expand or contract the subjective depth of stereoscopic pictures. Subjective assessments to verify the effectiveness of the algorithms were also conducted. The results suggest that the algorithms will allow viewers to experience a highly realistic sensation.
Our previous study showed that algorithms using quantified aerial perspective can control the subjective depth of stereoscopic images. With the superposition of spatial frequencies, the naturalness of processed images can be improved. In this paper, details of the algorithms and the results of a subjective assessment are presented and discussed.
This paper considers the architecture and the effectiveness of new algorithms which control the subjective depth on 3-D displays by modulating the contrast of stereoscopic images on the basis of a quantified monocular depth cue. The results suggest that the algorithms will allow people to feel a highly realistic sensation.
Our previous study showed that the algorithm using quantified aerial perspective could control subjective depth in stereoscopic still pictures. Being integrated with a motion-estimation technique, this algorithm can be applied to motion pictures. In this paper, details of the algorithm and results of subjective assessment will be presented and discussed. Motion Estimation Luminance Calculation Depth Estimation Contrast Analysis Frequency Analysis Modulation-amplitude Calculation Contrast Modulation L/R Pictures Input L/R Pictures Output Figure 3. Block diagram of the new image-processing algorithm for motion pictures. The algorithm consists of the six conventional and one additional motion-estimation blocks. SID 11 DIGEST • 909 61.1 / S. Takahashi
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