SAMPLE LEVEL VARIATION FOR SPATIAL SUB-SAMPLED IMAGES

A method for performing a sample level variation on an irregular sample is described herein. An initial sample level value for the sample is determined. An area of influence of the sample including pixels for which the sample is a factor in the prediction thereof is computed. Prediction errors of pixels in the area of influence are computed, along with a prediction error of the sample based on the prediction errors of the pixels. If the prediction error of the sample exceeds a prediction error threshold, a sample level change for the sample is computed based on only the prediction errors of the pixels. If the sample level change is less than a level change threshold, a new sample level value is assigned to the sample based on the sample level change.