Adaptive prediction

As you should observe, local structures in images are best predicted by different predictors. Thus we shall switch the predictors during coding time. In such situation we need to send side information indicating currently used predictor.

Alternatively, we can use adaptive predictor which selects a prediction depending on the neighbor's values. The simplest adaptive predictor may be described as:

if |c – b| > |c – a|	vertical edge is detected and prediction value is b
otherwise,	horizontal edge is detected and prediction value is a

JPEG-LS standard uses more advanced adaptive predictor which is described on picture below and implemented in the next interactive exercise.