Hue correction circuit for a digital TV receiver

摘要

A digital hue correction circuit for correcting the color of digital TV chrominance signals includes a pipelined divider arranged to divide the smaller of the magnitudes of I and Q color mixture signals by the larger of the magnitudes of the I and Q signals to produce quotients representing tangents over the range of zero to 45 degrees for chrominance angles occurring over the range of zero to 360 degrees. The polarity bits of the I and Q signals and the polarity bit of the difference of the magnitudes of I-Q are encoded to transpose the zero to 45 degree angle tangent values over the range of zero to 360 degree angles. The transposed tangent values address a memory programmed with all negative hue correction coefficients representing the sines and cosines of angles by which the chrominance vector is to be rotated to effect hue correction. The I and Q signals and the hue correction coefficients are applied to a complex multiplier to produce corrected I and Q color mixture signals I' and Q' according to the equations I'=I cos DELTA phi +/-Q sin DELTA phi Q'=Q cos DELTA phi -/+I sin DELTA phi .