Picture contrast-increasing arrangements
US4279003A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 1, 1979 |
| Grant date | Jul 14, 1981 |
| Priority date | — |
| Expiry date | Feb 1, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N1/4092
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Contrast is increased when reproducing originals, by using a first correcting signal for continuous-tone areas in the original and a second correcting signal which affects only line elements (narrow lines) in it. To generate a picture signal and a surrounding-area signal, an opto-electronic scanning member having a picture-point aperture and a surrounding-area aperture is provided. The diameter of the picture-point aperture is approximately equal to the width of the line elements in the original which are to be corrected. The first correcting signal is obtained from the picture signal and the surrounding area signal in a difference stage, and a selectable proportion of it is superimposed on the picture signal to increase sharpness. The difference stage is followed by a threshold circuit which allows positive parts of the first correcting signal lying above a first threshold and negative parts of the first correcting signal lying below a second threshold value to pass through, the parts which are allowed to pass through being superimposed on the picture signal as a second correcting signal, to increase sharpness for line elements. With the arrangement, the reproduction of line eleme…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.