A Signal-Dependent Error Arising in Digitally Processed Images Due to Quantization

A troublesome error has been found in digital data which represents an image renormalized by a computer. The error, which takes the form of anomalous patterns in the switching sequence of certain bits, contributes unnecessary, signal-dependent noise to the-data. Experimental results illustrating this phenomenon are shown and a theoretical model is derived. The model shows that the phenomenon results from a qtiantization or roundoff error inherent in digital renormalization and describes its detailed behavior. A method for rescaling the data which does not lead to the introduction of noise is described.