Patent ID: 6950469

Claim:
A method of interpolation in video coding in which an image comprising pixels arranged in rows and columns and represented by values having a specified dynamic range, the pixels in the rows residing at unit horizontal locations and the pixels in the columns residing at unit vertical locations, is interpolated to generate values for sub-pixels at fractional horizontal and vertical locations, the fractional horizontal and vertical locations being defined according to ½ x , where x is a positive integer having a maximum value N, the method comprising: a) when values for sub-pixels at ½ N−1 unit horizontal and unit vertical locations, and unit horizontal and ½ N−1 unit vertical locations are required, interpolating such values directly using weighted sums of pixels residing at unit horizontal and unit vertical locations; b) when values for sub-pixels at ½ N−1 unit horizontal and ½ N−1 unit vertical locations are required, interpolating such values directly using a choice of a first weighted sum of values for sub-pixels residing at ½ N−1 unit horizontal and unit vertical locations and a second weighted sum of values for sub-pixels residing at unit horizontal and ½ N−1 unit vertical locations, the first and second weighted sums of values being calculated according to step (a); and c) when a value for a sub-pixel situated at a ½ N unit horizontal and ½ N unit vertical location is required, interpolating such a value by taking a weighted average of the value of a first sub-pixel or pixel situated at a ½ N−m unit horizontal and ½ N−n unit vertical location and the value of a second sub-pixel or pixel located at a ½ N−p unit horizontal and ½ N−q unit vertical location, variables m, n, p and q taking integer values in the range 1 to N such that the first and second sub-pixels or pixels are located diagonally with respect to the sub-pixel at ½ N unit horizontal and ½ N vertical location.