A digital color space circuitry for conversion of Y/C to RGB, said circuitry comprising:
- means for separating a luminance/chrominance (Y/C) digital video signal input into Y, Cb and Cr component signals;
- means for brightness control for adding a constant value to the Y component signal, said means for brightness control including a brightness control switch for selecting a level of brightness control from one of a predetermined plurality of values, said means for brightness control include:
- (i) means for converting an unsigned 8 bits wide brightness signal to a 9 bits wide signed brightness signal, (ii) means for adding a signed brightness control value to a signed brightness signal and (iii) means for clipping the resulting signed brightness signal between the values of 0 and 255 (in case of an 8 bits bus width);
- means for hue control arranged to receive an input of the Cb and Cr signal components, the means for hue control includes means for converting unsigned 8 bit Cb and Cr signals into 9 bit signed signals that are clipped between values of 16 and 240, subsequently subtracting a value of 128 from the 9 bit signed signal and for performing the following functions on the respective Cb and Cr components:
- Cb—new=(cos A*(Cb−128)−sin A*(Cr−128))+128;
- and
- Cr—new=(sin A*(Cb−128)+cos A*(Cr−128))+128;
- where “A” is a degree of rotation;
- said means for hue control further includes a hue control switch for selecting one of plurality of predetermined values of hue control, means for converting each one of the plurality of predetermined switch positions into associated values of cosine and sin control values, said values of cosine and sin control values being multiplied by 255 to avoid floating point multiplication, said cosine and sin control values being fed to a multiplier, subsequently divided by 255 by a divider and a value of 128 added to the values divided by 255 by an adder;
- means for contrast control for multiplying the luminance Y signal by a contrast control constant value, said means for contrast control including a contrast control switch for selecting a level of contrast control from one of a predetermined plurality of values, said means for contrast control includes:
- (i)means for converting a 10 bit wide output signal from a selected one of a plurality of Y/C-to-RGB converter look-up tables, whose input is a Y signal to a 8 bit wide signal, (ii)means for multiplying the 8 bit wide signal by a contrast control constant value, and (iii)means for dividing an output of the multiplication of the multiplied 8 bit wide signal times the constant value by 128;
- means for saturation control for multiplying chrominance component signals Cb and Cr by a constant value, including a saturation control switch for selecting a level of saturation control from a plurality of predetermined saturation control levels, saturation control look-up tables for convening the selected value of the saturation control switch to a coefficient value, and means for multiplying the input of the chroma signals having positive values by a saturation coefficient associated with the saturation control switch for a particular setting.