1. A method for simulating film grain in an input image block, in which film grain has been at least partially filtered out, comprising the steps of: (a) computing an average value of at least one image parameter for the block; (b) selecting a film grain block from at least one previously established pool of film grain blocks whose image parameter most closely matches the average value of the image parameter of the input image block; (c) blending the selected film grain block with the input image block.