A method for controlling a pair of shutter glasses utilized for viewing stereo images presented by a video output apparatus , the video output apparatus outputting a group of first images and a group of second images, alternately, the video output apparatus successively outputting a primary first image and at least a secondary first image, included in the group of first images in order, within a plurality of successive first image output periods, the video output apparatus successively outputting a primary second image and at least a secondary second image, included in the group of second images in order, within a plurality of successive second image output periods, one of the group of first images and the group of the second images being a group of left-eye images, the other of the group of first images and the group of second images being a group of right-eye images, the method characterized by : controlling a first shutter lens of the pair of shutter glasses to be switched between an on-state and an off-state, wherein the first shutter lens stays in the on-state within two first image output periods respectively corresponding to two secondary first images following two successive primary first images respectively, and the first shutter lens is switched from the off-state to the on-state and then switched from the on-state to the off-state for at least once during a first time interval between the two first image output periods respectively corresponding to said two secondary first images; and controlling a second shutter lens of the pair of shutter glasses to be switched between the on-state and the off-state, wherein the second shutter lens stays in the on-state within two second image output periods respectively corresponding to two secondary second images following two successive primary second images respectively, and is switched from the off-state to the on-state and then switched from the on-state to the off-state for at least once within a second time interval between the two second image output periods; wherein one of the first shutter lens and the second shutter lens is utilized for viewing left-eye images, and the other one of the first shutter lens and the second shutter lens is utilized for viewing right-eye images. controlling a first shutter lens of the pair of shutter glasses to be switched between an on-state and an off-state, wherein the first shutter lens stays in the on-state within two first image output periods respectively corresponding to two secondary first images following two successive primary first images respectively, and the first shutter lens is switched from the off-state to the on-state and then switched from the on-state to the off-state for at least once during a first time interval between the two first image output periods respectively corresponding to said two secondary first images; and controlling a second shutter lens of the pair of shutter glasses to be switched between the on-state and the off-state, wherein the second shutter lens stays in the on-state within two second image output periods respectively corresponding to two secondary second images following two successive primary second images respectively, and is switched from the off-state to the on-state and then switched from the on-state to the off-state for at least once within a second time interval between the two second image output periods; wherein one of the first shutter lens and the second shutter lens is utilized for viewing left-eye images, and the other one of the first shutter lens and the second shutter lens is utilized for viewing right-eye images. <EOS>