Enhanced intra-prediction coding using planar representations
The present invention provides low complexity planar mode coding in which a value of a bottom-right pixel in a prediction block is calculated from a value of at least one pixel in at least one of an array of horizontal boundary pixels and an array of vertical boundary pixels. Linear and bi-linear interpolations on the value of the bottom-right pixel and values of at least some of the horizontal and vertical boundary pixels to derive values of remaining pixels in the prediction block. A residual between the prediction block and an original block is signaled to a decoder.
1. A video decoding method for predicting pixel values of target pixels in a target block under a planar mode, the method comprising computer executable steps executed by a processor of a video decoder to implement:
calculating a first prediction value of a respective target pixel using linear interpolation between a pixel value of a horizontal boundary pixel horizontally co-located with a respective target pixel, the horizontal boundary pixel being from among a plurality of horizontal boundary pixels on an upper side of the target block, and a pixel value of one vertical boundary pixel from among a plurality of vertical boundary pixels on a left side of the target block, wherein the first prediction value consists only of a first value derived solely from the linear interpolation between the pixel value of the horizontal boundary pixel horizontally co-located with the respective target pixel and the pixel value of said one vertical boundary pixel;
calculating a second prediction value of a respective target pixel using linear interpolation between a pixel value of a vertical boundary pixel vertically co-located with a respective target pixel from, the vertical boundary pixel being among a plurality of the vertical boundary pixels on a left side of the target block, and a pixel value of one horizontal boundary pixel from among a plurality of the horizontal boundary pixels, wherein the second prediction value consists only of a second value derived solely from the linear interpolation between the pixel value of the vertical boundary pixel vertically co-located with the respective target pixel and the pixel value of said one horizontal boundary pixel; and
performing an integer arithmetic using a right-shift operation to a sum of the first and second prediction values of each target pixel to derive each prediction pixel value in a prediction block, wherein the prediction pixel value consists only of an average of the first and second prediction values, and the integer arithmetic uses “>>” operator which represents the right-shift operation.
2. A video decoder that predicts pixel values of target pixels in a target block under a planar mode; comprising a processor of a computer system and a memory that stores programs executable by the processor to:
calculate a first prediction value of a respective target pixel using linear interpolation between a pixel value of a horizontal boundary pixel horizontally co-located with a respective target pixel the horizontal boundary pixel being from among a plurality of horizontal boundary pixels on an upper side of the target block, and a pixel value of one vertical boundary pixel from among a plurality of vertical boundary pixels on a left side of the target block, wherein the first prediction value consists only of a first value derived solely from the linear interpolation between the pixel value of the horizontal boundary pixel horizontally co-located with the respective target pixel and the pixel value of said one vertical boundary pixel;
calculate a second prediction value of each target pixel using linear interpolation between a pixel value of a vertical boundary pixel vertically co-located with a respective target pixel, the vertical boundary pixel being from among a plurality of the vertical boundary pixels on a left side of the target block, and a pixel value of one horizontal boundary pixel from among a plurality of the horizontal boundary pixels, wherein the second prediction value consists only of a second value derived solely from the linear interpolation between the pixel value of the vertical boundary pixel vertically co-located with the respective target pixel and the pixel value of said one horizontal boundary pixel; and
perform an integer arithmetic using a right-shift operation to a sum of the first and second prediction values of each target pixel to derive each prediction pixel value in a prediction block, wherein the prediction pixel value consists only of an average of the first and second prediction values, and the integer arithmetic uses “>>” operator which represents the right-shift operation.