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Smooth Raster Character Expansion

IP.com Disclosure Number: IPCOM000060827D
Original Publication Date: 1986-May-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Kuo, CJ: AUTHOR

Abstract

A technique is described whereby character cells, as used in the creation of characters displayed on cathode ray tube (CRT) rasters, printers or any type of device which utilizes rasters to display characters, are expanded so as to create a family of fonts from one base font. This concept eliminates the need to store many different fonts of afamily, since only one size is needed. Other fonts are derived from the one font size. In prior art, raster character cells have been expanded by implementing individual picture elements (pels) into a square array, causing a staircase effect, in that the diagonal lines appear as a staircase. In order to have available families of fonts of different sizes, each size font was stored and referenced, as needed.

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Smooth Raster Character Expansion

A technique is described whereby character cells, as used in the creation of characters displayed on cathode ray tube (CRT) rasters, printers or any type of device which utilizes rasters to display characters, are expanded so as to create a family of fonts from one base font. This concept eliminates the need to store many different fonts of afamily, since only one size is needed. Other fonts are derived from the one font size. In prior art, raster character cells have been expanded by implementing individual picture elements (pels) into a square array, causing a staircase effect, in that the diagonal lines appear as a staircase. In order to have available families of fonts of different sizes, each size font was stored and referenced, as needed. This approach required extensive memory requirements and limited the user to only those sizes stored in memory. The expansion of raster character cells has been restricted because of the requirements of the virtual device interface (VDI). Here, integral multiples were required whereby each pel is enlarged to a full square array, i.e., an integral expansion of three would result in each pel becoming a 3x3 box. The technique described herein provides a facility to derive a family of fonts from a single font through the use of an associated table. Smooth character expansion results with little or no staircase effect. The technique relies on the concept that each line of pels has another line to which it is biased (bias line). Also, each pel is a rectangular array of distinct points. Since each pel is treated as a rectangular array of distinct points, an expanded pel is converted into a full array, or a part thereof. When the pel is not a full array, the expanded pel is any one or more adjoining and sharing a similar side of a rectangle which has been dissected by its diagonals. Points belonging to the chosen sections are turned on while points outside are turn ed off. Pels which were once ON could become an ar...