With the increasing application of stereoscopic displays, the performance of stereoscopic displays attracts more and more attention. Crosstalk is one of the main perceptual factors influence image quality and visual comfort. To eliminate the crosstalk of liquid crystal based stereoscopic displays, based on a novel image processing crosstalk cancellation method is proposed. The proposed method reduces crosstalk from the aspect of the observer, and the light measured when the non-observed channel has the same gray level as the observed channel is defined as the ideal light output of the channel under test. The light output characteristic of specific stereoscopic display is measured using time average luminance meter and look up table is derived for crosstalk reduction. The theoretical calculation results show that the proposed method reduces crosstalk by 75% in average. Besides, the proposed method makes full use of the light leaked from the other eye view, which improves the luminance by about 12% according to the experiment. The proposed method can be applied both on time-multiplexed and on spatial-multiplexed stereoscopic display technologies and is easily implemented.