1. An image information processing apparatus comprising: input means for inputting a binary image signal and an image clock signal for each picture element, the binary image signal being one which has been binarization-processed using a predetermined matrix; conversion means for converting the binary image signal input by said input means into a multi-level digital image signal of three or more levels, the multi-level digital image signal representing density data for each picture element, and said conversion means converting the binary image signal into the multi-level digital image signal without increasing the number of picture elements, wherein said conversion means further comprises line memories for delaying the binary image signal by a quantity corresponding to plural lines and performs the conversion in real time synchronously with the image clock signal using said line memories, and wherein said conversion means includes means for discriminating whether the binary image signal is a signal obtained by binarizing halftone portion or a signal obtained by binarizing a character portion and converts the binary image signal into a multi-level digital image signal in accordance with a discrimination result provided by said discrimination means; and smoothing means for the multi-level digital image signal obtained in said conversion means, wherein said smoothing means performs smoothing processing of the multi-level digital image signal for an area a size of which is smaller than a size of said predetermined matrix.