Method and apparatus for selecting compression method and for compressing file using the selected method
US5838821A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1996 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Mar 14, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T9/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and system for automatically determining a compression method to be used on a file. A histogram of the file is constructed in order to determine if there are a predetermined number of consecutive byte patterns below a set threshold. If this condition exists, the file is not an image file and compression can be performed using the lossless Lempel-Ziv compression method. If, over the range of the histogram, the file is above the predetermined threshold, the histogram is examined to determine if the average value in the histogram is in a central portion of the histogram. If it is not, the file does not represent an image and again, the Lempel-Ziv compression method is used. If both the byte patterns and the histogram exceed the predetermined threshold and the average of the histogram is in a central portion, the file is determined to contain an image. Based on the gradation or number of bits necessary to represent the byte patterns of the file, an appropriate image compression method is used to compress the file.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.