Patent ID: 7224486

Claim:
An image conversion method comprising: a binary to multi-level conversion step of converting a first binary area tonal image into a first multi-level image consisting of an assembly of pixels each having a pixel value according to an areal ratio of an associated divided area of a plurality of divided areas in said first binary area tonal image; a multi-level to multi-level difference arithmetic step of determining a value representative of difference between associated pixels between the first multi-level image and a second multi-level image, which consists of an assembly of pixels having pixel values after the first multi-level image is converted in pixel values of pixels; and a binary to binary conversion step of converting the first binary area tonal image into a second binary area tonal image in which the areal ratio of a respective area associated with each of pixels of the second multi-level image, of the first binary area tonal image is increased or decreased in accordance with the value representative of the difference between the associated pixels between the first multi-level image and the second multi-level image.