Method of and apparatus for generating color matte signals

Claim 3

A method according to claim 1, characterised in that the saturation and luminance values are both defined as 8 bit words and the hue is defined as a 10 bit word, the three most significant bits of the hue value forming the first part comprising the steps of: (1) inputting hue, saturation, and luminance values; (2) doubling the second part of the hue value; (3) detecting whether the first part of the hue value is 110 or 111 and if so converting the first part of the hue value to 000 or 001 respectively; (4) detecting whether the first part of the hue value is odd or even and if it is even inverting the second part of the hue value; (5) inverting the saturation value; (6) calculating the value of three colour components D, E and F according to the following equations D=1, E=(1-SH), and F=S where S is the saturation value S is the inverted saturation value and H is the doubled second part of the hue value inverted; (7) multiplying the values of D, E and F by the luminance value; (8) assigning the multiplied D, E and F values to registers for holding the R, G and B values in dependence on the segment defined by the first part of the hue value; (9) calculating Y', Cr' and Cb' values according to the following equations Y'=0.299R+0.587G+0.114B, Cr'=R-Y, and Cb'=B-Y; (10) scaling the Y', Cr' and Cb' values to form Y, Cr and Cb values; and (11) outputting the Y, Cr and Cb values.

Claim 5

A colour matte generator having variable luminance, saturation and hue controls, the colour matte generator comprising means for calculating R, G and B colour components from the luminance, saturation and hue values, characterised by means for storing the selected luminance saturation and hue values in digital form, means for calculating luminance (Y) and colour difference (Cr, Cb) component values from the R, G and B colour components and means for outputting the luminance and colour difference component values, wherein the hue control selects one of six segments formed by dividing each side of the colour triangle in half and specifies an intermediate value within the segment, the colour matte generator further comprising means for calculating three colour components from the hue, luminance and saturation values and means for assigning the calculated colour components to registers for holding the red (R), green (G) and blue (B) component values in dependence on the selected segment.

Claim 6

A colour matte generator having variable luminance, saturation and hue controls, the colour matte generator comprising means for calculating R, G and B colour components from the luminance, saturation and hue values, characterised by means for storing the selected luminance saturation and hue values in digital form, means for calculating luminance (Y) and colour difference (Cr, Cb) component values from the R, G and B colour components and means for outputting the luminance and colour difference component values, wherein the hue control selects one of six segments formed by dividing each side of the colour triangle in half and specifies an intermediate value within the segment, the colour matte generator further comprising means for calculating three colour components from the hue, luminance and saturation values and means for assigning the calculated colour components to registers for holding the red (R), green (G) and blue (B) component values in dependence on the selected segment.

Claim 7

A colour matte generator as claimed in claim 4 characterised by means for selecting a destination address for the luminance and colour difference component values and producing an output code specifying said destination.

Claim 8

A colour matte generator as claimed in claim 4 characterised by means for outputting the luminance and colour difference component values during the field blanking period.