1. A video encoding method comprising computer executable steps executed by a processor of a video encoder to implement an intra-prediction operation that derives a prediction block of a target block with boundary pixels of the target block interpolated along an intra prediction angle, wherein the boundary pixels comprise a horizontal array of horizontal boundary pixels and a vertical array of vertical boundary pixels, the intra-prediction operation comprising: obtaining a value of an inverse angle parameter, corresponding to the intra prediction angle, from a look-up table which lists values of inverse angle parameters in relation, respectively, to a plurality of different intra prediction angles; identifying at least some of the vertical boundary pixels located in the vertical array at positions which are a function of multiplication between the obtained value of the inverse angle parameter and a value of a horizontal location identifier which is a variable representing positions in an extension of an extended horizontal array; adding the identified at least some of the vertical boundary pixels as horizontal boundary pixels to the extension of the extended horizontal array; and using only the horizontal boundary pixels in the extended horizontal array, without using the vertical boundary pixels, to derive the prediction block of the target block, and wherein the horizontal location identifier takes values of −1. .. (size×the intra prediction angle)/rangelimit, where size represents a size of a target block to be predicted and rangelimit represents a range limit of the plurality of intra prediction angles, which is fixed to a constant of 32.