Abstract: A method and an apparatus for image denoising based on medium filter is disclosed according to the present invention. Such method and apparatus may be used to remove linear noise and random noise for the sensor, as well as the bad points in the sensor image, and to prevent over-denoising. The technical solutions includes selecting three groups of pixels from neighboring pixels of a current pixel, calculating medians ?1, ?2 and ?3 for the pixels in each group; calculating a reference luminance Y: Y=?2+[?1+?3?2*?2]*h*[1?k*var], where var=?3??1; determining whether the current pixel (cur_pixel) is a bad pixel; letting a temporary variable (tmp_data) be ?1 if the current pixel is a bad pixel; letting a temporary variable (tmp_data) be the current pixel value (cur_pixel) if the current pixel is not a bad pixel; determining whether the current pixel is located on an edge.