Do digital fonts have true optical sizes?

In metal type, the matrices were designed in different weights, sizes and styles.
Each single matrice was designed and cut individually to look right at the intended size (e.g. by thinning or thickening lines).
It was not simply a scaled version of a “mother font”:
a 24 pt letter scaled down to half its size would not look like the 12 pt letter of that type (and it would probably look a little malformed).
Tim Ahrens and Shoko Mugikura write about this.

Leap in time to the digital era:
I understand that there are formats which store information about a letter as a “shape of pixels” (bitmap, which makes letters blurry in too large sizes), and there are formats which store that information as a vector function (OpenType, which makes the font scalable).

When writing on a computer, it is possible to choose between a plethora of sizes (even fractions like 10.5 pt).
I assume that these are scaled sizes, which means that if you took a print of a 24 pt letter and scaled it down to 12 pt, it would look exactly like the letter that was originally printed in 12 pt.

If they work that way, neither of these two formats take into account what I described in the first paragraph.

Does modern digital typography address this, and if so, how?


Does modern digital typography address this, and if so, how?

They either do it through individual styles, which are then called “optical sizes”. For two versions, it is usually called “text” and “display”. But there can be more, like caption and subhead. In theory, software can even pick the right version automatically, but that is not well supported. So usually the font user chooses the correct version for the specific size.

Another approach is to seamlessly interpolate between so-called masters, e.g. a text and a display master. This was pioneered in the 1990s with GX and Multiple Master fonts, but it died as a technology. It is currently being revived as Variable Fonts. Note that this interpolation can have all sorts of purposes (e.g. weight, width, serifs …), but optical size can also be one of them.

Source : Link , Question Author : Philipp , Answer Author : opentype

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