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.