Browse Prior Art Database

Image Data Compression Algorithm

IP.com Disclosure Number: IPCOM000089653D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 40K

Publishing Venue

IBM

Related People

Greene, WB: AUTHOR [+2]

Abstract

This algorithm reduces the storage area required for matrix images when images for multiple type fonts are being utilized. Reference is made to the figure.

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Image Data Compression Algorithm

This algorithm reduces the storage area required for matrix images when images for multiple type fonts are being utilized. Reference is made to the figure.

Some of the terms used are as follows:

Control Field. The control field consists of four bits. If a bit is set to "1", it indicates that the image matrix is to be used.

Zero Repeat Field. The zero repeat field indicates how many zero images are to be used following the current image matrix.

Image Matrix Field. The image matrix is the pattern that is to be used to display or print a matrix. These images might be part of various font patterns, such as pica, elite, or proportional spacing type style. They could also be various languages where the same EBCDIC value would represent different characters.

Image Word. An image word has the above three fields that may vary in length depending on the application. In the same manner, the number of image words used to represent a character will vary depending on the similarity of the character. The number "1" would be the same for all countries, but the letter A would be different since some countries have accent marks over the letter A. However, some of the image words would be the same for the letter A.

Since there are times when a program needs to use different fonts and/or languages. this compression method will allow less storage. Once the control has been established, the program will look at each image word to verify if it is to be used. If its control bit is set to "1", the image matrix will be used to set the output bits. Next, the program checks the zero repeat field to find how many images of zeros are to be used.

Table 1 represents the first pass wire image for the character A that is presently stored for each of the four type fonts used for enhanced printing. Each one requires 40 words (Wds) so that a common addressing algorithm can be used to access them, totalling 160 words. TABLE 1 10CPI 12 CPI P.S. No. 1 P.S. No. 2 4 Wds 0000...