Patent ID: 7995653

Claim:
A method of finding the prediction direction of a current image block during intraframe image coding, the method calculating virtual blocks associated with said current block in given prediction directions, which method comprises the following steps: selecting two initial prediction directions (E, S) from the given prediction directions, calculating virtual blocks associated with said initial prediction directions (E, S), comparing said virtual blocks with the current block and selecting the initial prediction direction (E) that minimizes the difference between the associated virtual block and the current block, which prediction direction is then called the first main direction, calculating virtual blocks associated with the prediction directions (ENE, ESE) immediately adjacent to said first main direction (E), comparing the virtual blocks associated with the first main direction (E) and said immediately adjacent directions (ENE, ESE) with the current block to determine the best prediction direction, which is the prediction direction that minimizes the difference between the associated virtual block and the current block, if said best prediction direction is said first main direction (E) or one direction (ENE) of the immediately adjacent directions if it is situated at one extremity of the set of prediction directions, determining that said best direction is the prediction direction of the current image block, otherwise, selecting the prediction direction (ESE) that minimizes the difference between the associated virtual block and the current block, which is then called the second main direction, calculating the virtual block associated with the prediction direction (SE) other than the first main direction (E) that is immediately adjacent to the second main direction (ESE), comparing the virtual blocks associated with the second main prediction direction (ESE) and with said immediately adjacent direction (SE) with the current block to determine the best prediction direction, which is the prediction direction that minimizes the difference between the associated virtual block and the current block, if said best prediction direction is said second main direction (ESE) or the immediately adjacent direction (SE) if it is situated at one extremity of the set of prediction directions, determining that said best direction is the prediction direction of the current image block, otherwise, continuing the process iteratively until the prediction direction of the current image block is determined.