Color halftone error-diffusion with local brightness variation reduction
US5991438A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 1997 |
| Grant date | Nov 23, 1999 |
| Priority date | — |
| Expiry date | Jul 31, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/52
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Error diffusion algorithms such as the celebrated Floyd Steinberg error-diffusion algorithm are high-performance halftoning methods in which quantization errors are diffused to "future" pixels. Originally intended for grayscale images, they are traditionally extended to color images by error-diffusing each of the three color planes independently (separable error-diffusion). Adding a design rule which is based on certain characteristics of human color perception to the error-diffusion paradigm results in a color halftoning algorithm having output of considerably higher quality when compared to separable error-diffusion. These benefits are achieved by adding the Minimum Brightness Variation Criterion (MBVC) to the design rules of color error-diffusion halftoning methods. Halftone values are constrained to be vertices of a Minimum Brightness Variation Quadruple (MBVQ) associated with each pixel of the color image being processed. The algorithm presented requires no additional memory and entails a reasonable increase in run-time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.