PROCESS FOR SEPARATING FOREGROUND INFORMATION FROM BACKGROUND INFORMATION IN A DOCUMENT

摘要

Disclosed is a process for separating foreground information from background information in a document, the foreground information being additively or subtractively overlaid with the background information. The invention provides that in a first step the document is divided into a large number of segments and in a second step a frequency distribution of extreme values of the signal intensities is determined in each of the segments. The resulting frequency distribution has an essential mode (background mode) that contains essentially the background information. If the first two steps do not yield a sufficient foreground/background separation, a sharper separation can be effected through a third step of determining a frequency distribution of signal intensities of the entire document and a fourth step of combined evaluation of the two frequency distributions determined. In a fifth step to determine a threshold value of a signal intensity of the background information in the document, this threshold value is derived either from a flank of the background mode inclined toward the foreground information or from a flank of another essential mode opposite the background mode, preferably by a linear approximation of a point on one of the flanks of the two essential modes.