1. An image processing system which comprises an object pixel detecting means which determines whether relevant pixels in the character image information obtained by reading an original on which characters have been recorded are object pixels to be subjected to enhancement processing and carries out enhancement processing on pixels determined to be object pixels, thereby carrying out edge enhancement processing on the character image information, wherein the improvement comprises that the object pixel detecting means comprises a density judgment section which determines the relevant pixel to be a prospective object pixel when the density of the relevant pixel is higher than a first threshold value higher than the density of the background of the border of the original and not higher than the density of a thinnest line in lines which form said characters and is not higher than a second threshold value not lower than the density of a thinnest line in lines which form said characters, and a thin line image detecting section which determines the relevant pixel to be a thin line pixel forming a part of a thin line image, and determines that the relevant pixel is an object pixel when the density judgment section determines the relevant pixel to be a prospective object pixel and the thin line image detecting section determines the relevant pixel to be a thin line pixel.