1. A method for increasing the accuracy of physiological signals obtained from a video of a subject being monitored for a desired physiological function, the method comprising: receiving image frames of a video captured by a video imaging device of a subject being monitored for a desired physiological function, said image frames being acquired of at least a portion of an exposed body region of said subject where a physiological signal corresponding to said desired physiological function can be registered by said video imaging device; defining a size N of a batch of image frames such that N min ≦N≦N max , where N min is a minimum size of a batch of image frames and N max is a maximum size of a batch of image frames; and for each batch of image frames of size N: processing the current batch of image frames to isolate pixels associated with said body region; processing said isolated pixels to obtain a time-series signal for this batch; determining whether a movement occurred during video acquisition of this batch of image frames; and in response to said movement being below a predetermined threshold level, updating the parameters of a predictive model using said obtained time-series signal, otherwise: using said updated predictive model to generate a predicted time-series signal for the current batch; and fusing said time-series signal with said predicted time-series signal to obtain a fused time-series signal for the current batch.