1. A method for automatically removing noise comprising the steps of: a) receiving a current pixel; b) computing an activity metric of the current pixel by using the current pixel and a neighborhood of pixels related to the current pixel; c) computing a distance metric for indicating the likelihood that the current pixel is a background pixel by using the activity metric and at least one background parameter; and d) modifying the current pixel based on the distance metric; wherein the distance metric provides a soft thresholding framework.