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36 2 Hybrid Video Coding
Figure 2.9 Intra 4 × 4 prediction. (a) the prediction of pixels a–p is conducted from pixels A∼Q;
(b) Eight prediction directions for a 4 × 4 block.
2.3.2 Intra Prediction
Originally, H.264 had two different intra predictions: 4 × 4 prediction and 16 × 16
prediction. The 4 × 4 prediction is well suited for coding of parts of a picture with
significant detail. The 16 × 16 prediction is more suited for coding very smooth areas
of a picture. The 8 × 8 prediction is introduced later in the high profile.
When using the 4 × 4 prediction, each 4 × 4 block is predicted from spatially
neighboring pixels as illustrated in Figure ...