AN IMAGE HAVING A DISCRIMINATOR FOR DISCRIMINATING AN INSIDE AREA AND AN OUTSIDE AREA

A digital image of a document having chromatic and achromatic colors is read, and an edge of a black character is discriminated. Further, an outside area and an inside area of the edge are detected. Edge emphasis is performed on an inside area of the edge for data of achromatic colors. On the other hand, data of chromatic colors in an inside area of the edge is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel. Data of chromatic colors and of achromatic colors in the outside area is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel.