Patent ID: 8588301
Filing Date: 2013-11-19
Classification: H04N

Abstract:
1. An image coding apparatus which divides an input picture into a plurality of blocks and performs an encoding process by selecting one of an inter-prediction mode and an intra-prediction mode for each block, comprising: a flatness determination unit adapted to calculate flatness based on pixel values contained in a block of interest and determine whether the block of interest is a flat block; a storage unit adapted to store determination results by said flatness determination unit for each block; an area determination unit adapted to determine, based on the determination results stored in said storage unit, whether the block of interest determined to be a flat block by said flatness determination unit belongs to an area made up of a collection of predetermined quantity of the flat blocks; a prediction mode selection unit adapted to select one of the inter-prediction mode and the intra-prediction mode as a prediction mode for an encoding process of the block of interest based on determination results by said area determination unit and on cost values of the inter-prediction mode and the intra-prediction mode, the cost values having been calculated using a cost function which represents coding efficiency; and a coding unit adapted to perform predictive coding according to the prediction mode selected by said prediction mode selection unit, wherein said prediction mode selection unit is further adapted to: calculate the cost value for each of the inter-prediction mode and the intra-prediction mode based on a difference between a reference picture and the input picture, wherein the reference picture is referred to in the encoding process; and correct the calculated cost values, in the case of the block of interest belonging to the area, a ratio of the cost value of the intra-prediction mode to the cost value of the inter-prediction mode increases and select one of the prediction modes by comparing the corrected cost values.