US Patent 7379124 Center convergence optimization in a projection display apparatus

Progressive rounding error and convergence error encountered due to multiple use of a center correction adjustment of an image of a video projection display is reduced by calculating a 3×3 matrix for a moved color signal where the non center matrix values represent the difference between the initially measured sensor values stored at initial alignment, and stored most recently measured sensor values. The matrix center value is the sum of the averaged values calculated from the edge center errors, the stored sum of previous moves and the current move. Rerun of the sensor finding routine resets the stored move sum to zero.