Patent ID: 9152875
Filing Date: 2015-10-06
Classification: G06K,H04N

Abstract:
1. A method of encoding image frames, each image frame containing a plurality of macro-blocks, each of the plurality of macro blocks formed of a plurality of pixels, the method comprising: receiving a macro-block in an image frame; determining whether the macro-block contains text; computing a quantization parameter for quantizing the macro-block, wherein the quantization parameter is computed to be smaller than a predetermined value if the macro-block is determined to contain text, wherein the determining comprises calculating a gradient for each pixel in each of a plurality of sub-blocks in the macro-block, computing, corresponding to each of the plurality of sub-blocks, an edge pixel count value representing the number of pixels with gradients greater than a first threshold value, selecting the highest of the edge pixel count values determined by the computing, classifying the macro-block as containing text if the highest of the edge pixel count values selected by the selecting has a value between a second threshold value and a third threshold value; and encoding the macro-block using the quantization parameter.