Multi-level image quantization with object-dependent spectral control

The iterative Fourier transform algorithm (IFTA) allows quantization with c ontrol of the spectrum of the output image, and therefore offers the possib ility to shape the quantization noise to conform to the low-pass properties of the visual system. The windowed IFTA (WIFTA) extends the IFTA by proces sing on local windows, and therefore allows an adaptation to local object d ependent parameters. The extension of this algorithm from two-level to mult i-level output offers additional free parameters. We discuss the possibilit ies and limitations of an adaptation of the low-pass cut-off frequency and the local histogram distribution to the local gray value. (C) 2000 Elsevier Science B.V. All rights reserved.