Recursive video hue rotations to obtain a rainbow-like decaying

Abstract

An apparatus creates a 'rainbow-like' effect in a decaying video afterimage by including a chrominance phase rotator within a recursive video effects loop, so that the hue of the afterimage is recursively altered as it decays. The chrominance phase rotator can be placed anywhere within the recursive loop, and can also be combined with a blurring effect and/or the decay factor multiplication needed for the basic recursive circuit. Several variants of the circuitry for providing chrominance phase rotation are provided; some suitable for processing cosited chrominance components, others suitable for processing noncosited chrominance components. Additional variations conserve the number of parts required at the expense of technical color accuracy by making simplifying assumptions. A variation is also provided on a folded FIR filter that was disclosed in a previous patent for blurring video trails, the variation combining the blurring function and the chrominance phase rotation function to produce blurred and rotated chrominance values concurrently. Similarly, placing a saturation modification circuit within the recursive video loop produces increasing or decreasing color effects as the afterimage decays.