Abstract: An original picture having a standard or non-standard picture quality is converted into a halftone picture, which is to be reproduced, on basis of pictorial information. The density information on the individual density characteristic curve is adjusted to the density information on the standard density characteristic curve. The adjusted density information is then processed in such a way that the base density of a desired control point on the original picture and the halftone intensity of a corresponding control point on the halftone picture are correlated in accordance with a specific conversion formula.