Font Typesetting Function 08: “Metrics Kerning”

Metrics kerning is kerning based on information inside the font (set in advance by the font maker). In Japanese metrics kerning, the value is set on the assumption that proportional metrics are already applied. As Latin is originally proportional, it is possible to apply kerning directly. In the case of Japanese, a two-stage procedure is required: make it proportional first, and then adjusting the spacing between specific characters by kerning. Without proportional metrics, metrics kerning cannot be applied.

Therefore, when metrics kerning is specified in InDesign/Illustrator, proportional metrics is applied at the same time.

It is complicated to make adjustment manually after applying metrics kerning. When kerning is performed manually, the kerning mode is transferred from metrics kerning to value specified. As a result, proportional metrics applied based on metrics kerning become invalid, and sensitively mysterious action occurs. To avoid this, I recommend utilizing metrics kerning upon explicitly applying proportional metrics (by doing so, the effect of proportional metrics remains even when the kerning mode is transferred).

(mm)