Type 1 Fonts: Adobe's Legacy Font Format

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The Invention of PostScript Type 1

Adobe Systems introduced PostScript in 1984, a landmark page description language that transformed professional printing. At its core, PostScript treated a page as a mathematical description: draw a curve of this shape, place text at this position in this typeface, fill this region with this colour. The result was device-independent output that could be rendered crisply at any resolution on any PostScript-capable output device.

Type 1 was the font format Adobe created to accompany PostScript. First published in 1984 and refined through the late 1980s, Type 1 fonts defined letterforms as cubic Bézier curves — precise mathematical outlines that could be scaled to any size and rendered at any resolution without degradation. Adobe initially kept the Type 1 specification proprietary, restricting other vendors from creating Type 1 fonts. This changed in 1990 when Adobe published the specification openly, triggering a rapid expansion of the Type 1 font market across dozens of foundries.

The combination of PostScript and Type 1 fonts was the technological foundation of the desktop publishing revolution of the late 1980s and 1990s. Together with Aldus PageMaker (later Adobe PageMaker), the Apple LaserWriter, and the Apple Macintosh, they made professional-quality typesetting accessible outside traditional print shops for the first time.

How Type 1 Fonts Work Technically

A Type 1 font typically consists of two files: a PFB (Printer Font Binary) file containing the encrypted PostScript outline data, and a PFM (Printer Font Metrics) file containing the spacing and kerning information used by the operating system to lay out text. On macOS, the equivalent structure used a suitcase file for the metrics alongside a separate outline file.

The outline data in a Type 1 font is encoded in a subset of the PostScript language, using a compact charstring encoding (called the Type 1 charstring format) to describe each glyph. The font program includes a set of private data — called the Private dictionary — that encodes information about the font's dominant stem widths, alignment zones, and other metrics used by the hint processor to improve rendering quality at small sizes and low resolutions.

Hinting is the mechanism by which a font program gives instructions to the rasteriser about how to adjust the mathematical outlines when rendering at small sizes on low-resolution devices, such as screen displays or early laser printers. Type 1 hinting was relatively sophisticated for its era, producing good output at a range of sizes on devices from 300 dpi laser printers to high-resolution imagesetters.

Type 1 vs. TrueType vs. OpenType

In 1991, Apple and Microsoft jointly released TrueType as a competing font format, partly motivated by the desire to reduce dependence on Adobe's proprietary technology. TrueType used quadratic Bézier curves (rather than Type 1's cubic curves), a different hinting approach — with instructions written in a TrueType-specific bytecode language — and a single-file format that was simpler to deploy than the two-file Type 1 structure.

OpenType was developed jointly by Adobe and Microsoft in the late 1990s and published as an open standard. OpenType is a wrapper format that can contain either Type 1 (cubic) or TrueType (quadratic) outlines, designated by the file extensions .otf (OpenType with PostScript/cubic outlines) and .ttf (TrueType or OpenType with TrueType/quadratic outlines). OpenType added critical capabilities missing from both predecessors: Unicode character encoding for extended language support, advanced typographic features (ligatures, small caps, alternate characters, swash variants) through the GSUB and GPOS tables, and a single cross-platform file format that works identically on Windows and macOS without conversion.

By the early 2000s, OpenType had become the professional standard. The Type 1 vs. TrueType distinction, once a significant practical concern, became largely academic.

Adobe Type Manager

A key piece of infrastructure for Type 1 fonts on desktop systems was Adobe Type Manager (ATM), first released in 1989. Before ATM, Type 1 fonts on screen were rendered using low-resolution bitmap versions of the typeface — one bitmap for each point size — resulting in jagged, coarse text on displays at sizes not covered by an installed bitmap. ATM intercepted the screen rendering calls from the operating system and rendered Type 1 outline fonts directly to the screen, producing smooth, scalable type at all sizes. It was a significant quality improvement and helped cement Type 1's position as the professional font format through the 1990s.

As operating systems gained their own outline font rendering (Apple's QuickDraw GX and later Quartz, Microsoft's ClearType on Windows), ATM became less necessary. Adobe discontinued ATM as a standalone product around 2013, and it was eventually removed from the list of supported products entirely.

Type 1 Fonts in PDF

PDF inherited its imaging model and font technology from PostScript, and Type 1 fonts have been a supported font type in PDF since the format's 1993 debut. When a Type 1 font is embedded in a PDF, the font program — the glyph outlines and metrics — is stored within the PDF file itself, ensuring that the document can be rendered correctly on any system regardless of whether the font is installed locally.

PDF supports three embedding modes for Type 1 fonts: full embedding (the complete font program), subsetting (only the glyphs actually used in the document, reducing file size), and not embedding (relying on the font being present on the rendering system, which is unsuitable for reliable document exchange). The PDF specification also permits the use of Type 1 fonts without embedding if they are among the PDF Base-14 standard fonts — a set of 14 Type 1 designs including Helvetica, Times Roman, and Courier that every conforming PDF viewer is required to have available.

Adobe's End of Support for Type 1 in 2023

Adobe announced in January 2023 that it was ending support for Type 1 fonts across its Creative Cloud applications, including Illustrator, InDesign, Photoshop, and other tools in the suite. From that point, Type 1 fonts installed on a system no longer appear in the font menu in updated Creative Cloud applications. Design files that previously used Type 1 fonts report those fonts as missing when opened in updated application versions, and font substitution is applied, potentially altering the visual appearance and text reflow of affected documents.

Importantly, this change affects only the authoring applications. Adobe Acrobat's ability to display and process existing PDF documents that contain embedded Type 1 font data is not affected — PDFs with embedded Type 1 fonts continue to render correctly. The impact is on the creation and editing side rather than on the reading and processing of existing PDFs.

The reason for the change is straightforward: Type 1 is a technology from the 1980s. Maintaining the code to support it in modern applications represents ongoing engineering overhead, and OpenType has comprehensively replaced it for all practical purposes. The vast majority of professional typography workflows have been running on OpenType for many years; the end of Type 1 support is the formal close of a chapter that had already effectively ended.

Migrating from Type 1 to OpenType

For organisations with workflows that depend on specific Type 1 fonts, the migration path is to obtain OpenType equivalents. For fonts originally created by Adobe, OpenType versions are available through Adobe Fonts (included with Creative Cloud subscriptions) or as perpetual licences from font retailers. For fonts from other foundries — Linotype, Monotype, URW, ITC, and many others — the foundry should be contacted directly for OpenType upgrade paths, which are widely available and often offered at a discount to existing licence holders.

Automated conversion of Type 1 files to OpenType is technically possible but not recommended for brand-critical typefaces: metrics can shift subtly, hinting may be degraded, and character outlines may be affected. Obtaining a properly engineered OpenType version from the original source is always preferable.