To solve a problem that in a conventional method for converting an image contrast pattern comprising many parallel lines, the image quality is deteriorated due to moire or the like caused by incompatibility among a spatial frequency characteristic of an image scanner and an image printer, a spatial frequency characteristic of an image contrast pattern comprising many parallel lines and a spatial frequency characteristic of an image itself when the scanner captures an original including an image comprising many parallel lines and the printer prints out the received image.

The method for converting an image contrast pattern comprising many parallel lines includes a many parallel line management step of analyzing input pixel data to recognize many parallel lines in an image and managing the many parallel lines as a many parallel line parameter, an image conversion step of applying image conversion to an image required to enhance the image quality of an output image on the many parallel line parameter and a many line pixel output step of generating the output pixel data from the many parallel line parameter. Since this method can provide output pixel data suitable for a characteristic of the many parallel line image and a characteristic of an image output device, an image subjected to proper image conversion only to the many parallel line image can be outputted.