| 摘要 |
A thermal printing system is disclosed in which a graphic image composed of a succession of lines having the same number of pixels each is scaled both horizontally and vertically by a factor of approximately 1.5 without altering the size of the pixels. The system disclosed replaces each 2 by 2 set of pixels with a 3 by 3 set of pixels. Each 2 by 2 set consists of two immediately adjacent pixels from the same line and the two immediately adjacent pixels from the next succeeding line. The corner pixels of the 3 by 3 set are identical to the four corner pixels of the 2 by 2 set. The intermediate pixels of the first and third lines have densities equal to the average of the densities of the two corner pixels on the same lines of the same set. The three pixels of the second line of the 3 by 3 set have densities equal to the respective averages of the densities of the pixels immediately adjacent to them in the first and third lines. In this manner, a standard 1024 pixel by 1280 pixel graphic image is transformed into a 1536 by 1920 pixel graphic image. When printed by a thermal printer using a FAX head with 8 dot per millimeter resolution, the resulting image loses substantially nothing of importance in the way of definition and is substantially equal in size to one printed with a standard head with 6 dot per millimeter resolution.
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