Mastering Lucas de Groot Optical Progression for 9-Weight Font Families
Why linear mathematical interpolation ruins font weight balance, and how DIYglyphs native C++ engine uses geometric optical progression formulas.
The Optical Illusion of Font Weights
When expanding a font from Thin (100) to Black (900), linear mathematical interpolation (t = 0.5) makes medium weights look far too heavy and unreadable.
The Lucas de Groot Formula
Renowned type designer Lucas de Groot developed the geometric progression standard used in professional foundries:
$$W_i = W_0 \cdot \left(\frac{W_n}{W_0}\right)^{\frac{i}{n}}$$
This formula distributes the visual mass proportionally across Thin 100, ExtraLight 200, Light 300, Regular 400, Medium 500, SemiBold 600, Bold 700, ExtraBold 800, and Black 900.
How DIYglyphs Automates This in C++
With DIYglyphs AIP, select your Thin and Black vector paths, pick Lucas de Groot, and click 1-Click 9-Weight Family. The plugin instantly spawns all 9 layers on your Illustrator canvas in under 0.1 seconds!
Try DIYFonts & DIYglyphs in Illustrator
Export font families with auto-spacing and 60 FPS interpolation without leaving Illustrator.