Method and apparatus for pre-prediction filtering for use in block-prediction techniques

A method for reconstructing blocks of an image using prediction, the method comprising:

• determining reference samples of one or more already decoded blocks for predicting a block to be reconstructed, the reference samples corresponding to a prediction mode employed for encoding the block to be reconstructed;
• selecting a first subset of the reference samples and a second subset of the reference samples;
• determining first filter parameters for the first subset of the reference samples and second filter parameters for the second subset of the reference samples based on the prediction mode and a size of the block to be reconstructed, the first filter parameters being different than the second filter parameters;
• performing first pre-prediction filtering of the first subset of the reference samples and the second subset of the reference samples using the first filter parameters and the second filter parameters, respectively, to generate first filtered reference samples;
• selecting a third subset of the reference samples for which no residual has been coded in an encoded video stream;
• performing second pre-prediction filtering of the third subset of the reference samples using third filter parameters to generate second filtered reference samples;
• and
• reconstructing the block by prediction based on the reference samples including at least some of the first filtered reference samples, the second filtered reference samples, or a combination thereof.

An apparatus for reconstructing blocks of an image using prediction, the apparatus comprising:

• a reference sample buffer for storing one or more already decoded blocks including reference samples used for predicting a block to be reconstructed, the reference samples corresponding to a prediction mode employed for encoding the block to be reconstructed;
• a processor configured to:
• select a first subset of the reference samples and a second subset of the reference samples;
• and
• determine first filter parameters for the first subset of the reference samples and second filter parameters for the second subset of the reference samples based on the prediction mode and a size of the block to be reconstructed, the first filter parameters being different than the second filter parameters;
• a filter coupled to the processor and adapted to perform pre-prediction filtering of the first subset of the reference samples and the second subset of the reference samples using the first filter parameters and the second filter parameters, respectively, to generate pre-prediction filtered reference samples;
• and
• a predictor coupled to the processor and configured to reconstruct the block by prediction based on the reference samples including the pre-prediction filtered reference samples.

A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to:

• determine reference samples of one or more already decoded blocks used for predicting a block to be reconstructed, the reference samples corresponding to a prediction mode employed for encoding the block to be reconstructed;
• select a first subset of the reference samples and a second subset of the reference samples;
• determine first filter parameters for the first subset of the reference samples and second filter parameters for the second subset of the reference samples based on the prediction mode and a size of the block to be reconstructed, the first filter parameters being different than the second filter parameters;
• perform pre-prediction filtering of the first subset of the reference samples and the second subset of the reference samples using the first filter parameters and the second filter parameters, respectively, to generate pre-prediction filtered reference samples;
• and
• reconstruct the block by prediction based on the reference samples including the pre-prediction filtered reference samples.