An impulse removal algorithm is proposed to overcome the difficulty of detail preservation which is commonly encountered by existing methods. At the impulse detection stage, a directional impulse detection method is employed to avoid the misclassification of thin lines as impulses. As for the noise filtering stage, a hybrid algorithm which combines median-based filtering with pattern matching technique is adopted. Experiments show that the proposed approach outperforms a number of existing algorithms and the improvement on detail preservation is significant.