Method and apparatus for data compression of bitmaps using rows and columns of bit-mapped printer data divided into vertical slices
US5930466A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 11, 1997 |
| Grant date | Jul 27, 1999 |
| Priority date | — |
| Expiry date | Mar 11, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06K2215/0077
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
An improved printing system is provided that compresses bitmap print data by determining, per each vertical slice of a horizontal swath of the printed page, which one of two different data compression techniques to more efficiently compresses each individual slice, then temporarily stores this compressed data in a memory circuit until needed by the printhead for actual printing of the final output in the form of print media. When using slices containing seven (7) different words per slice, the present invention utilizes a single "control bit" of a "control word" to represent each of the data words of the slice. Depending upon which type of compression technique is used, the control bit for each data word will be set to either Logic 1 or Logic 0, depending upon the value of the data word as compared to a pre-determined data word value that is chosen by the system, and which may be used in both types of data compression techniques. After each slice has been analyzed by both types of data compression techniques, certain of the data words in the slice can be temporarily discarded, leaving behind less than seven (7) data words to represent that slice as compressed data. This compressed …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.