A method and system are provided. The method includes storing a set of references images without rain and spanning a plurality of different light conditions. The method further includes capturing, using a camera, an image of a scene with rain. The method also includes selecting a reference image from the set of reference images based on the light condition of the captured image. The method additionally includes performing an arithmetic subtraction image processing operation between the captured image and the reference image to generate a subtraction image. The method further includes estimating an amount of rain in the subtraction image based on previously calibrated values.