separate binarization noise from low frequencies of the image. In case of low

Image and spectral control in electronic half toningManfred Broja, Frank Wyrowski, and Olof BryngdahlUniversity of Essen, Department of Physics4300 Essen 1, Federal Republic of GermanyIn electronic halftoning binarization algorithms are applied to convert graylevelimages into binary ones. The local gray value of a binary image is given as a localaverage over black and white (0 and 1) pixels. Electronic binarization algorithms allowus to use binary working printing and display devices to present graytone images.To compare a graylevel and a binary image a spectrum representation is convenient.