Simultaneous magnification of subtle motions and color variations in videos using riesz pyramids

Abstract

Videos often contain subtle motions and color variations that cannot be easily observed. Examples include, for instance, head motion and changes in skin face color due to blood flow controlled by the heart pumping rhythm. A few techniques have been developed to magnify these subtle signals. However, they are not easily applied to many applications. First of all, previous techniques were targeted specifically towards magnification of either motion or color variations. Trying to magnify both aspects applying two of these tech niques in sequence does not produce good results. We present a method for magnifying subtle motions and color variations in videos simultaneously. Our approach is based on the Riesz pyramid, which was previously used only for motion magnification. Besides modifying the local phases of the coefficients of this pyramid, we show how altering its local amplitudes and its residue can be used to produce intensity (color) magnification. We demonstrate the effectiveness of our technique in multiple videos by revealing both subtle signals simultaneously. Finally, we also developed an Android application as a proof-of-concept that can be used for magnifying either motion or color changes.