System for producing dithered images from continuous-tone image data
US4955065A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 10, 1989 |
| Grant date | Sep 4, 1990 |
| Priority date | — |
| Expiry date | Oct 10, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4052
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A digital image processing system for converting continuous tone pixel values representing an image into halftone or dithered pixel values, with the dithered pixel values representing each pixel having fewer bits than are used to represent each pixel in the continuous tone image. The continuous tone pixel for a line of pixels is loaded into an input buffer circuit having a plurality of storage locations, with each location storing the continous-tone values for one pixel. Iteratively, the pixel value from each location is modified by a perturbed weighted error value, and then quantized to form the output halftone or dithered pixel value. An error value is then determined which is used in processing of subsequent continuous tone pixel values. The processing of the continuous tone pixel values proceeds in a serpentine manner over the image, that is, processing of adjacent lines of the continuous tone pixel data proceeds in opposite directions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.