A method for compressing graphics data comprises selecting z-planes from a plurality of z-planes. The selected z-planes are predictor z-planes. A residual is determined for each sample not covered by one of the predictor z-planes. A sample is covered by one of the predictor z-planes when the predictor z-plane correctly defines a z-value of the sample. A residual comprises a value that is a difference between a predicted z-value provided by one of the predictor z-planes and an actual z-value for the sample. The predictor z-planes and the residuals are stored in a z-buffer.