Interocular distance measurement method and correction method

A correction method implementable by a three-dimensional display device, the display device including

• a display configured to display a parallax image projected toward a first eye and a second eye of a user through an optical system,
• a barrier configured to define a traveling direction of image light of the parallax image to provide parallax between the first eye and the second eye,
• a detector configured to detect a position of a face of the user, and
• a controller,
• the correction method comprising:
• displaying an image for interocular distance measurement in a viewable section of the display determined based on a reference value of an interocular distance;
• detecting a first position of the face of the user in response to an instruction from the user, the instruction being based on an image viewable with the first eye;
• detecting a second position of the face of the user in response to an instruction from the user, the instruction being based on an image viewable with the second eye;
• calculating an interocular distance of the user through correction of the reference value based on the first position and the second position;
• and
• correcting the display based on the interocular distance of the user.