Moving images displayed on liquid crystal displays,typical representative of hold-type displays,will generate motion artifacts such as motion blur.This degradation of image quality can be explained by the low-pass characteristic of MTF of LCD when moving images displayed on it.The theory of modulation transfer function and its applications in evaluation of mage quality are introduced.With this theory,the frequency characteristics of LCDs displaying motion images,influences of LC response time on motion blur and effects of backlight blinking method on improvement of motion blur are analyzed.