Image processing of leaf movements in Mimosa pudica

Abstract

In this paper the plant Mimosa pudica’s response to changed illumination conditions is being examined. An image processing routine, using the HSV color model and triangle intensity threshold segmentation, is developed to segment time-lapse image series of Mimosa pudica, quantifying the plant’s image pixel count as a measure of movement. Furthermore, the method of Farnebäck is used to estimate dense optical flow (both magnitude and direction), describing the plants movement orientation in the image plane. The pixel count results indicate that the plant exhibits an anticipatory behavior in that it starts to close its leaves prior to the light-to-dark transition. Furthermore, the optical flow results indicate that each compound leaf show different behavior depending on the whereabouts in the circadian rhythm cycle. This suggests that a complex regulating structure lies behind the plant’s response to different illumination regimes.