Screen patterns used in offset-printing become visible or cause moir? noise in the images if the documents are scanned at high resolution such as 400dpi or more. This has been an obstacle in developing document recognition systems which handle color documents. This paper proposes a new method for filtering screen patterns/noise in high-resolution color document images. The method utilizes a wavelet analysis for screen pattern detection. Experimental results show that our method can smear periodic screen patterns effectively preserving thin character strokes.