Elimination of the effect of difference in vertical scanning frequency between a display and a camera imaging the display

摘要

An imaging system that images a raster-scanned display receives the vertical synchronizing signal of the raster-scanned display, and has a synchronizing signal generator for generating the vertical synchronizing signal of the imaging system. According to a first aspect of the invention, the output of the imaging system is multiplied by a compensation signal that compensates for brightness differences due to a difference in frequency between the two vertical synchronizing signals. According to a second aspect of the invention, the vertical synchronizing signal of the imaging system is delayed from the vertical synchronizing signal of the raster-scanned display by an amount calculated so that no such brightness difference occurs in the part of the raster-scanned display viewed by the imaging system.