Glyphs-Handbook-2013

For an in-depth discussion, see:
typophile.com/files/hinting.pdf,
partners.adobe.com/public/
developer/en/font/T1_SPEC.PDF
(specifically pages 35 – 45) and
vimeo.com/38364880.
8 Hinting
8.1 FONT-WIDE HINTING SETTINGS
Before you do glyph-level hinting, you need to define a
set of parameters that apply to all hinting throughout
the font. These font-level hints are stored in the so-called
‘PostScript Private Dictionary’ inside the exported font.
This is why sometimes, these settings are referred to as
‘private parameters’.
8.1.1 Standard Stems
The autohinter needs good standard stem values in order
to recognize the stems and apply hints automatically.
And the screen rasterizer can make use of these values to
optimize the pixel rendering, especially synchronizing stem
thicknesses across the whole font at low resolutions. Try to
find representative values for your horizontal and vertical
stem widths and enter them in the Masters tab of Edit > Font
Info (Cmd-I). Theoretically, up to twelve width values can be
considered for each direction, but try to use as few values as
possible. Best practice is to use only two vertical values, one
for lowercase and one for uppercase, e.g., the stem widths of
lowercase i and uppercase I, or a representative value between
the stem widths of i/I and the bowl widths of o/O. The same
applies to horizontal stems, like the horizontal bars of t/T, f/F,
e/E etc. The first value you enter is the most important one.
Use a value that represents your most-used glyphs, typically
the lowercase letters. Any values that follow are used for the
StemSnapH and StemSnapV parameters, respectively.
You can quickly measure the thickness if you select two
nodes and take a look at the grey info box (Cmd-Shift-I). For
instance, if you measure 68, 71, 72, 74, 75, 82, 83, 85 for your
vertical stems, then you would pick 72 and 83 as standard
vertical stems, because these are good median values for most
of the stem measures.
In a Multiple Master set-up, values in individual masters
are interpolated, so make sure you enter the values in the
same order in each master.
8.1.2 Alignment Zones
When your font is rendered with very few pixels on a
computer screen, all the x-heights should align to the same
Glyphs Handbook, May 2013 67