Patent ID: RE43357

Claim:
An alternating-line color interpolator and edge detector comprising: an input for receiving a stream of mono-color pixels from an image sensor; a 2-line buffer, coupled to receive pixels from the input, for storing a full line of pixels and portions of 2 other lines of pixels, the 2-line buffer outputting a 3×3 region of pixels having 3 rows and 3 columns; a red interpolator, receiving red pixels in the 3×3 region from the 2-line buffer, for averaging the red pixels within the 3×3 region to generate an interpolated red pixel for a center location of the 3×3 region; a blue interpolator, receiving blue pixels in the 3×3 region from the 2-line buffer, for averaging the blue pixels within the 3×3 region to generate an interpolated blue pixel for a center location of the 3×3 region; a green interpolator, receiving green pixels in the 3×3 region from the 2-line buffer, for averaging the green pixels within the 3×3 region to generate an interpolated green pixel for a center location of the 3×3 region; wherein for odd lines the green interpolator averages only green pixels in a middle column of the 3×3 region when the center location is on an odd line, the green interpolator ignoring green pixels in a left column to the left of the middle column and in a right column to the right of the middle column for odd lines; wherein for even lines the green interpolator averages only green pixels in a middle row of the 3×3 region when the center location is on an even line, the green interpolator ignoring green pixels in an upper row above the middle row and in a lower row below the middle row for even lines; and an edge detector, receiving green pixels in the 3×3 region from the 2-line buffer, for multiplying each green pixel by a filter coefficient and for summing results to generate an edge value; wherein for odd lines, the filter coefficients for green pixels in a middle column have an opposite sign as filter coefficients for green pixels in the right and left column, whereby edges crossing the middle column are magnified more than vertical edges within the middle column for odd lines; wherein for even lines, the filter coefficients for green pixels in a middle row have an opposite sign as filter coefficients for green pixels in the upper and lower row, whereby edges crossing the middle row are magnified more than horizontal edges within the middle row for even lines, whereby vertical color interpolation and horizontal edge detection is performed for odd lines, but horizontal color interpolation and vertical edge detection is performed for even lines.