Abstract
The halftone method that utilizes their characteristics by combining different halftone algorithm is one of the challenges of producing high quality halftone image. An important factor that influences the combined different halftone algorithm is the contour emerging in the gray level between different halftone areas. This paper proposes a new halftone algorithm to reduce the contour between different halftone frequencies. The authors investigated the contour perception that occurs from image reproduction and found that the contour between different halftone frequencies is hard to perceive when the difference in the frequency spectrum is sufficiency small. A novel halftone algorithm, which modulates halftone frequency gradually according to density level, has been proposed. The proposed halftone algorithm, based on a cluster dot dithering algorithm, generates a fixed minimum dot size. The proposed algorithm obtains a better subjective estimation value.
