Vignette color component value generation method and apparatus

摘要

A method of generating color component values of a vignette, the values being permitted to lie between upper and lower limits comprises generating a nominal vignette value; and modifying the nominal vignette value by a randomly chosen amount, the randomly chosen amount lying within a predetermined range. The predetermined range within which the random amount may lie narrows in accordance with the nearness of the nominal vignette value to the upper and lower limits.