Patent ID: 6970273

Claim:
A method of tone reproduction of an image with halftone dots by forming dots arranged at regular intervals and having different sizes on an image reproduction medium based on a binary or multivalued image out of digital image data representing a single color component or a plurality of color components, comprising the steps of: growing the halftone dots in a circular or elliptical shape in a first transformation zone from a halftone percentage of 0% to a first highlight percentage; growing the halftone dots while changing from the circular or elliptical shape to a square or rhomboidal shape in a second transformation zone from the first highlight percentage to a second highlight percentage greater than said first highlight percentage; growing the halftone dots in a square or rhomboidal shape in a third transformation zone from the second highlight percentage to a second shadow percentage; growing the halftone dots while changing from the square or rhomboidal shape to a circular or elliptical shape in a fourth transformation zone from the second shadow percentage to a first shadow percentage greater than said second shadow percentage; and growing the halftone dots in a circular or elliptical shape in a fifth transformation zone from said first shadow percentage to a percentage of 100%.