Methods And Systems For Image Intra-Prediction Mode Management

An apparatus for decoding a current block of image, the apparatus comprising:

• a decoder comprising one or more processing devices, the decoder configured to:
• select an intra prediction mode, and
• predict pixel values of the current block using the selected intra prediction mode,
• wherein to select the intra prediction mode, the decoder is configured to:
• a) determine an estimated prediction mode based on prediction modes of a first block adjacent and above the current block and a second block adjacent and left of the current block,
• b) receive a first information indicating whether the estimated prediction mode is to be selected as the intra prediction mode of the current block,
• c) receive a second information indicating an actual best prediction mode to be selected as the intra prediction mode of the current block when the estimated prediction mode is different from the actual best prediction mode, and
• d) select either the estimated prediction mode or the actual best prediction mode in a set of prediction modes as the intra prediction mode, based on the first and second information,
• wherein, if the first block is not available, the estimated prediction mode is determined to be DC prediction mode regardless of the prediction mode of the second block,
• when the selected intra prediction mode is the DC prediction mode and the first block is not available, all pixels of the current block are predicted to have a value equal to (I+J+K+L+2) right shifted by two bits, and
• wherein I, J, K, and L are pixel values in an adjacent block immediately to the left of the current block.