1. A noise reduction system for an image frame, comprising: a noise estimation module configured to generate noise parameters indicative of a global noise variance from each frame using a parameter-based model by comparing an input frame and a past filtered frame, and calculating a local mean of the input frame, the noise estimation module comprising: an absolute difference calculating module that calculates an absolute difference of the input frame and the past filtered frame; and a histogram generator coupled to the absolute difference calculating module, the histogram generator receiving the calculated local mean and the absolute difference and classifying the absolute difference in a histogram bin according to its local mean; a local variance calculator coupled to the noise estimation module, the local variance calculator configured to convert the global noise variance indicated by the generated noise parameters into a local noise variance; an adapted spatio-temporal filter that filters the local noise variance along with the input and the past filtered frames and outputs a current filtered frame; and a frame buffer storing the current filtered frame for use as the next past filtered frame.