Image quantization by a windowed iterative Fourier transform algorithm with local object dependent control

The iterative Fourier transform algorithm (IFTA) is the image quantization algorithm which allows global control of the spectral distribution of quantization noise. In general the spectral distribution of the image information varies locally in the image. A windowed iterative Fourier transform algorithm (WIFTA) is proposed, which allows to vary the spectral control of the quantization noise locally in the image. Thus the algorithm can be adapted to the local image information. This local object dependent control can be utilized to preserve the image information to a larger extent than with a space invariant control.