TrueType Font-Level Hinting
TrueType instructions refer to shared control values so related glyphs can make consistent rounding decisions. FontLab exposes that setup through named zones, stems, and additional rendering parameters.
TrueType Alignment Zones
The Control Value Table, or CVT, supplies values used by the compiled instructions. FontLab's named zones and stems provide an editable source model for those relationships.
Open Zones from the TrueType Hinting workspace. A top or bottom zone has a name, an alignment position, and an extent toward the overshoot region. Give important heights distinct, meaningful names, because alignment instructions refer to them.
TrueType zones are not restricted to the PostScript seven-primary/five-secondary arrangement. Add the heights your design needs, while keeping the set understandable. More zones do not automatically improve rendering.
Save the source before importing if you need to preserve a customized TrueType zone set. Import TT Zones from Font Info seeds the setup from the PostScript zones. The normal import covers masters; Alt limits the operation to the current master. Review the imported names and values before replacing an established TT setup.
Expand a zone's master rows to edit its position and width for each source design. Use Apply to inspect changes without closing the dialog, then retain or cancel them deliberately.
The expanded zones show values for Regular and Bold. The delta table at the bottom belongs to the selected x-height zone.
Adjust a zone at particular sizes
Zone deltas alter the gridfitted alignment at chosen PPMs. Use the selected zone's delta table or its on-canvas control at the active PPM. These are size-specific pixel adjustments, not a permanent movement of the source zone in font units.
For a problem at 12 PPM, select the affected zone, add or adjust its delta at 12, then compare the result at 11, 12, and 13 PPM. This separates the correction at the problem size from changes that belong in the zone’s source position.
Check all glyphs aligned to that zone. A correction made to help one letter changes a shared reference and can affect many others. Review neighboring sizes and masters before accepting it.
TrueType Standard Stems
Open Stems in the TrueType Hinting workspace. A TrueType standard stem has a name that link instructions can use. Its value and rounding behavior coordinate related strokes across glyphs.
Use Import TT Stems from Font Info for a starting set from PostScript stems. Check the current-master indication and the intended import scope. Expand master rows when the values need to vary across the designspace.
The TT set is not limited by the PostScript stem-snap array size, but a small coherent set is easier to manage than a separate standard for every measured stroke.
Set jump PPMs
A jump PPM is the size at which a stem's rounded pixel width increases. The stem controls expose transitions through one to eight pixels. Moving a transition can change the apparent weight at a range of small sizes without changing the source outline.
Each stem expands into master rows. The numbered columns show the jump PPMs for the corresponding pixel widths; the values shown here are specific to this font.
Select a stem to edit its jump values, and compare related glyphs in the waterfall. Optimize PPM and Reset PPM process both horizontal and vertical stem lists across all masters, not just the selected row. Optimize proposes revised jumps; Reset restores the calculated unoptimized progression. Review the other stems and masters after either operation.
For example, if a stem grows to two pixels at 14 PPM but looks too heavy at 14 and 15, try moving its two-pixel jump to 16. Compare 14, 15, and 16 PPM, then check the following jump and related stems. The trial delays one rounding transition; it does not make the source stem thinner.
Coordinate related horizontal and vertical stems so an accidental mismatch in their transitions does not produce an unwanted contrast change at one size.
Stem snap precision is expressed in sixteenths of a pixel. It controls the allowed difference for snapping an actual scaled measurement to a declared rounded stem. A broader tolerance favors uniformity; a narrower tolerance preserves more distinctions. Use the preview to judge that tradeoff rather than choosing the largest value automatically.
Other Parameters and Smoothing
The workspace's Other Parameters controls include small-size weight transitions such as ppm2 and ppm3. They help determine when a stem progresses from one to two or three pixels in the relevant rendering mode. Change them while comparing a group of related glyphs and sizes.
Other Parameters combines stem snap precision, hinting cutoffs, waterfall sizes, and sample texts. The displayed numbers are example settings.
Font Info > Other Values > Use TrueType hinting selects the hinting or compilation route. Current choices include FontLab TTH, VTT compilation for visual TT Hinting commands, TTFAutohint, and no TrueType hinting. The autohinting workflow is taught in TrueType Autohinting; inspect the export profile for how existing instructions are retained, rebuilt, or omitted.
No smoothing up to PPM supplies the gasp threshold for monochrome rendering; above it smoothing is requested, and 0 requests smoothing at all sizes. No vertical smoothing up to PPM is the current label for the horizontal-only ClearType threshold; above it symmetric smoothing is requested, and 0 uses an automatically calculated threshold. Consumers and rendering modes can interpret these requests differently, so inspect the target output.
Keep the shared parameters with the source project. Interchange formats can store FontLab visual programs in application-specific data such as com.fontlab.ttcommands, but another editor need not interpret that data as the same editable system.
Link instructions refer to the defined stems by name; see Visual TrueType Instructions. Application-specific UFO storage, including com.fontlab.ttcommands, and other format details are covered in Interchange and Legacy Formats.