A digital image quality enhancing method that enhances a quality of a document image comprising pixels with a predetermined resolution and obtained by scanning a script comprising a combination of a background, a text, and an image. The method includes: updating history information according to a pixel type of a concerned pixel using previous history information of the concerned pixel; determining a block feature type of the concerned pixel using the pixel type and the updated history information of the concerned pixel; determining a type of an area to which the concerned pixel belongs based on a second type of a second area to which a first neighbouring pixel in a left direction of the concerned pixel belongs, a third type of a third area to which a second neighbouring pixel in a line above the concerned pixel belongs, the pixel type of the concerned pixel, and the determined block feature type; and performing different image quality enhancing processes based on the determined area type.