Digital film archives are often damaged by aging and multiple playing

such as dust spots

dirt

blotches

film unsteadiness

line scratches

flicker

noises

color variations and blurs

witch may cause some artifacts on the films. This paper introduces a method for blotch detection. The initial detection is gained by using an improved SROD algorithm. And then postprocessing module is achieved through two EM steps

thus eliminating the effect of noise and determining blotch. Experimental results show that the blotch detection method proposed in this paper is effective and can be easily implemented.