Roger D. Hersch, Claude Bétrisey
U.S. Patent No. 5,768,490
Methods are proposed for visually evenly spacing of two successive characters taking into account outline shape modifications induced by character grid-fitting. Visually even spacing of characters is obtained by converting the geometric space between two characters into its visually perceived equivalent space. Converting between geometric and visually perceived spaces requires transformations applied to the character outlines for smoothing out the character borders and replacing them by virtual borders which represent the boundaries of the perceived intercharacter space. The optimal visual distance between the origins of two successive characters is obtained by requiring the characters to have a perceived visual space equal or close to an ideal perceived visual space called ideal optical intercharacter space extracted from by design optimally spaced character pairs such as "nn" for lower-case characters and "HH" for capital letters.
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