Serial digital video processing with concurrent adjustment in RGB and luminance/color difference

A digital converter for an input video data signal having successive samples of at least three data values representing luminance and hue information defining the samples according to a first color space definition, the converter comprising:

• at least two color space converters in cascade along a data path between a data input and a data output, a first said color space converter being operable to convert successive sets of the data values from the first color space definition to a second color space definition, and a second said color space converter being operable to convert successive sets of the data back to the first color space definition;
• at least one value adjustment circuit operable to perform a numeric function on the successive sets of the data values using coefficients applicable to the data values, the adjustment circuit being coupled to at least one of the two color space converters for performing the numeric function to correct the data values in at least one of the color space definitions;
• a controller coupled to the at least one value adjustment circuit and to an input, the controller being responsive to signals on the input to control the numeric function effected by the adjustment circuit for altering the luminance and color difference information contained in the data values;
• and,
• wherein the successive samples are provided at the input according to a YCbCr luminance and color difference color space definition, wherein the adjustment circuit includes a matrix multiplier operable to multiply the data values by the coefficients provided to the adjustment circuit by the controller, and wherein each of the YCbCr components are applied to the matrix multiplier in a two's complement form, and wherein the Y component of the luminance and color difference is artificially offset to provide approximately equal distribution of allowable values above and below zero, whereby outputs of the matrix multiplier range substantially through a full dynamic quantization span in a variably offset translation of an RGB color space definition.

A digital converter for an input video data signal having successive samples of at least three data values representing luminance and color information defining the samples according to a first color space definition, the converter comprising:

• at least two color space converters in cascade along a data path between a data input and a data output, a first said color space converter being operable to convert successive sets of the data values from the first color space definition to a second color space definition, and a second said color space converter being operable to convert successive sets of the data back to the first color space definition;
• at least one value adjustment circuit operable to perform a numeric function on the successive sets of the data values using factors applicable to the data values, the adjustment circuit being coupled to at least one of the two color space converters for performing the numeric function to correct the data values in at least one of the color space definitions;
• and,
• a controller coupled to the at least one value adjustment circuit and to an input, the controller being responsive to signals on the input to control the numeric function effected by the adjustment circuit for altering the luminance and color difference information contained in the data values;
• and,
• at least one auxiliary color space converter, the auxiliary color space converter being arranged to perform the numeric function using reduced values of one of the data values and the factors, and further comprising means for comparing an output of the auxiliary color space converter and one of the first and second color space converters, and generating an overflow code when said one of the first and second color space converters produces an output having a sign different from a sign of the output of the auxiliary color space converter.