METHOD OF RESTORING PICTURES WITH HIGH DENSITY

In a picture restoring method, an original picture is read with low density into picture elements arranged in the form of a grid, and the density data of the picture elements is subjected to decimal quantization to provide the density level of the picture elements. According to the decimal quantization density levels, the density levels of eight sets of picture elements, with three adjacent picture elements among picture elements around an aimed picture element as one set. The aimed picture element is divided into nine minute picture elements in the form of a grid. The density levels of the eight sets of picture elements are used to determine whether the minute picture elements are white or black. When more than four black minutes picture elements are around a minute picture element which has been decided white, the latter is converted into a black minute picture element.