Patent ID: 6877863
Filing Date: 2005-04-12
Classification: G03B,G06T,H04N

Abstract:
1. A projection method for automatically correcting keystone distortion within an optical image that is projected onto a projection surface through a projection lens having a projection axis that is oriented in a direction that is off-axis from the surface normal of the projection surface, said projector method comprising the steps of: (a) obtaining input image data representing the optical image to be displayed; (b) determining the absolute horizontal direction of the projection axis, the absolute vertical direction of the projection axis, a vertical zero reference and a horizontal zero reference by: (c) calculating the vertical difference angle by subtracting the vertical zero reference from the absolute vertical direction of the projection axis and the horizontal difference angle by subtracting the horizontal zero reference from the absolute horizontal direction of the projection axis; (d) determining the keystone distortion based on the vertical difference angle and the horizontal difference angle; and (e) applying geometric correction to the image data proportional and inverse to said keystone distortion such that the projected image is free from keystone distortion.