Patent ID: 7693326

Claim:
A computer-implemented method for converting image data from a RGB model to a YCbCr model, wherein average down-sampling is used to convert the data, the method comprising the steps of: receiving data that represents a plurality of input components of an image that includes a red component, a green component and a blue component, wherein the plurality of input components are in a format compatible with the RGB model and each of the plurality of input components has a plurality of sub-components; summing up the plurality of sub-components for each of the plurality of input components; multiplying the respective sums of the red component, the green component and the blue component with a first set of corresponding coefficients, which are equal to −0.04219, −0.082815 and 0.12500, respectively, to obtain a first set of three resulting products; summing up the first set of three resulting products and a constant to obtain a representation for a chrominance component for blueness, the representation for a chrominance component for blueness being in a format compatible with the YCbCr model, wherein the chrominance component for blueness is determined by fifteen computations, and each computation is either a multiplication or an addition computation; multiplying, by an image processing microprocessor or codec, the respective sums of the red component, the green component, and the blue component with a second set of corresponding coefficients, which are equal to 0.12500, −0.10467 and −0.02033 respectively, to obtain a second set of three resulting products; summing up the second set of three resulting products and the constant to obtain a representation for the chrominance component for redness, the representation for the chrominance component for redness being in a format compatible with the YCbCr model, wherein the chrominance component for redness is determined by six computations, and each computation is either a multiplication or an addition computation, and wherein the microprocessor for image processing is configured to perform the steps of receiving data, summing up the plurality of sub-components, multiplying the respective sums of the red component, the green component and the blue component with a first set of corresponding coefficients, summing up the first set of three resulting products, multiplying the respective sums of the red component, the green component and the blue component with a second set of corresponding coefficients, and summing up the second set of three resulting products.