Image processing apparatus including horizontal and vertical scaling for a computer display
US6014125A · kind A · utility
Assignees
Inventor
Key dates
| Filing date | Dec 8, 1994 |
| Grant date | Jan 11, 2000 |
| Priority date | — |
| Expiry date | Dec 8, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G2340/0421
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A scaling apparatus is disclosed for horizontally and vertically scaling scan line information stored in a video memory prior to providing the scan line information to a computer display. Horizontal scaling apparatus is provided in which a first clock signal is provided for graphics portions of scan lines and a second clock signal is provided for video portions of scan lines. The second clock signal is enabled in a manner such that the second clock signal exhibits a predetermined phase relationship with respect to the first clock signal from scan line to scan line. The frequency of the second clock signal is selected to determine the scaling of the video portion of the scan line. Vertical scaling apparatus is provided in which scan line information corresponding to first and second scan lines is retrieved from a video memory. A digital differential analyzer, external to the central processing unit, then determines respective weights for the first and second scan lines dependent on the amount of vertical scaling desired. The weights for the first and second scan lines are then provided to a weighted adder which adds the first and second scan lines according to these weights.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.