TrueType Autohinting

Autohinting supplies an initial instruction program. The preparation depends on the selected engine, and the resulting program still needs review in the TrueType workspace and in the intended output.

Prerequisites for TrueType Autohinting

FontLab TTH translates existing PostScript hints rather than independently analyzing outlines. Useful PS hints and font-level zones/stems are a prerequisite for this engine; without them it has no structural hint data to translate. Prepare them through Alignment Zones and Standard Stems and PostScript Autohinting. The PS zones and stems become the corresponding TrueType data. This differs from PostScript autohinting’s outline analysis and does not impose the same prerequisite on TTFAutohint.

TTFAutohint is a separate engine with its own outline-analysis workflow. It does not depend on FontLab's PostScript hints in the same way. Choosing it does not mean the FontLab visual-program controls describe every part of its operation.

Select the intended engine through the font's TrueType settings and the export profile. A profile can defer to the Font Info choice. Check the effective selection rather than changing preferences for one engine while exporting with another.

Review the glyph set, contours, master compatibility, and H/V hinting ranges before a broad pass. Keep the source version with any manual hints you may need to recover.

Running TrueType Autohinting

The TT Autohint Action in Tools > Actions, taught in Actions, supplies the batch route; select the intended glyph scope before applying it. Remove TT hints removes the corresponding source instruction data when you deliberately want to start again.

TT Autohint is a separate action from PostScript Autohint.

TT Autohint is a separate action from PostScript Autohint. Check its glyph and master scope before running it.

You can retain cubic source outlines and generate supported visual TT instructions for later TrueType output. That does not make the cubic source itself a native quadratic font; the export must still perform the appropriate conversion and compilation.

For a quadratic-source workflow:

  1. Save a copy of the original source.
  2. Convert the intended contours to TrueType curves using the selected conversion tolerance.
  3. Set the appropriate contour direction.
  4. Inspect the converted shapes and point structure; simplify only where the drawing remains acceptable.
  5. Prepare the required source hints, zones, and stems, then run TT Autohint.
  6. Open representative glyphs in the TrueType Hinting workspace and review the programs.

UPM and conversion tolerance affect the quadratic point count. A large UPM can produce enough points to make automatic control less reliable; when needed, use Clean Up after conversion to reduce unnecessary points, accepting and checking the resulting small shape adjustments. Preserve the original and compare the outline. Recall curve conversion in Segments and Curve Types and contour direction in Curves, Direction, and Fill.

The brown T cell indicator identifies visual TT hinting. It confirms that instructions are present, not that the family has passed small-size testing. In a variable source, keep the main-master basis and corresponding geometry coherent.

Autohinting Controls

Under Preferences > Autohinting, Single link attachment precision controls how closely a measured stem must match a named TT standard before the generated link uses it. A tighter tolerance preserves distinctions; a looser one favors shared widths. The value uses source font units, unlike the pixel-based TT stem-snap precision.

The FontLab engine also offers controls for:

  • Triple-hint relationships coordinate repeated stems, such as those in m, so their intervening distances can remain consistent as the pixel size changes.
  • Link direction chooses whether links progress from the left sidebearing toward the right, or from both sidebearings toward the center. Compare which strategy keeps the glyph balanced.
  • Cusp interpolation adds an Interpolate instruction for a sharp change of contour direction, relating that point to the controlled geometry rather than leaving its position to the general interpolation alone.
  • Middle deltas add small corrections at the ends of links controlling rounded parts. Inspect those sizes before keeping the extra adjustments.
  • Right-sidebearing linking connects the rightmost hinted point to the right-sidebearing point with a rounded distance, helping retain space beside the rendered drawing. Check the resulting spacing in text.
  • Double-link interpolation can hint the first of overlapping stems, as in B, then derive the second stem’s position by interpolation with its final point aligned to the grid.

Enable options to solve a known problem, then inspect the resulting instructions. Avoid assuming that every checkbox should be on or that one preferred combination suits all designs.

Export controls distinguish the chosen engine, use of existing visual TTH commands, retention of imported native hinting, and rebuilding PostScript hints before translation. Those policies determine whether the output preserves your work, regenerates it, or omits it. Review them before final export; see Export Profiles.

Fine-Tuning Results

Start with font-level consistency. Compare related glyphs in the waterfall, then adjust zone alignment and stem jump PPMs where a shared change is appropriate. Merge near-equal stem definitions when they represent the same intended thickness, then inspect the family. For small-size weight transitions such as ppm2/ppm3, lowering the transition size makes the stem reach the heavier pixel width sooner; raising it keeps the lighter width longer. Adjust the Stems, Zones, and Other Parameters controls described in TrueType Font-Level Hinting while judging the family rather than one glyph.

Then inspect individual programs. Correct mistaken stem associations, poor alignment bases, or unnecessary instructions before resorting to final deltas. Compare both Black-and-White and ClearType previews and the actual intended consumers.

The Reassign TT stems and Reassign TT zones Actions help remap existing instructions when the named font-level setup changes. Check their scope and resulting references; renaming or replacing a control value is not merely a cosmetic operation.

Recheck several sizes after every broad adjustment. The expected finish is a coordinated rendered result, not the largest number of instructions or a program that happens to look good at one PPM.

The Reassign TT stems and Reassign TT zones batch Actions are covered in Actions.