US Patent 7268821 Upconversion with noise constrained diagonal enhancement

A method of interpolating a given output pixel value when upconverting interlaced video to progressive video includes the step of determining averages for vertically adjacent pixels, left diagonally adjacent pixels, and right diagonally adjacent pixels respectively for the given output pixel and the step of determining differences between the vertically adjacent pixels, the left diagonally adjacent pixels, and the right diagonally adjacent pixels respectively. The method further selects as an interpolated value for the given output pixel among the averages based on a minimal difference of an absolute value among the differences respectively and further constrains the interpolated value to the value of the average of the vertically adjacent pixels if a value of the given output pixel is not between a range of values defined by adjacent pixels above and below the given output pixel or if the selected minimal difference is not unique.