GRADIENT-BASED PIXEL INTERPOLATION

In a method for determining a data value for a target pixel in a destination image based on data values for pixels in a source image, with the destination image being scaled relative to the source image, calculating a position in the source image based on position of a target pixel in the destination image, testing the presence of a diagonal gradient in the source image at the position determined in the calculating step, the testing step testing for the presence of a diagonal gradient by reference to values of pixels in the source image that surround the position calculated in the calculating step, responsive to the presence of a diagonal gradient in the testing step, calculating a data value for the target pixel based on interpolation of data values for diagonally-adjacent pixels in the source image, and responsive to the absence of a diagonal gradient in the testing step, calculating a data value for the target pixel based on interpolation of data values for at least all four surrounding pixels in the source image.