Videotek, Inc.

Robert E Stenzel

Donald E Groff

A digital converter controllably modifies input video data representing pixel luminance and color information, in two color space formats. Two color space converters are coupled in cascade. Serial video data is converted to parallel and demultiplexed. A first color space converter converts 4:2:2 sampled YCbCr luminance and color difference input data to RGB red/green/blue format. A second color space converter changes the data back to YCbCr before remultiplexing at the output. Under operator control from front panel inputs, a controller varies the conversion coefficients at the input-side color space converter, including by trigonometric functions applied to the coefficients to provide controllable hue phase shifting, modifies the transfer function in RGB color space by adjusting data in the lookup tables, and applies maximum/minimum clipping levels. Interpolation doubles the sample rate of CbCr color difference data at the input for co-siting each Y sample with a CbCr color difference for processing samples at 4:4:4. Two's complement computations, including for luminance Y, employ the full dynamic quantization range of the color space converters. An auxiliary color space converter operates on divided coefficients for detecting overflow. A bypass delay route is provided for non-video data, and error detection and handling signals are passed through as well as compared and generated for the changed data.

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Phoenixville, PA, United States of America

Robert E Stenzel