TechNote (Archived)

PostScript Type 1 and Type 3 Fonts General Information

What's Covered

Type 1 Fonts

Type 3 Fonts

Distinguishing Type 1 from Type 3 Fonts

Adobe developed the Type 1 font specification and produces and distributes many Type 1 typefaces. The Type 1 font specification was originally proprietary, but Adobe released the specification to third-party font manufacturers provided that all Type 1 fonts adhere to it. In addition, Adobe developed the Type 3 font specification, also available to third-party font manufacturers, but has never produced or distributed Type 3 fonts. Adobe Type Manager and many applications don't support Type 3 Fonts.

Type 1 Fonts

Type 1 fonts, also called PostScript fonts, contain defined character shapes in an encoded PostScript format and contain hints in their character definitions. Hints help font outlines to be reproduced (for example, printed) while maintaining the font's shape at low resolutions. For example, hinting improves the printed appearance of small text printed to a 300 dpi PostScript printer.

Advantages of Type 1 fonts include:

--Outline (printer) font files contain more precise definitions than Type 3 outline font files, enabling Type 1 fonts to print with greater detail.

-- You can download Type 1 fonts to a printer's ROM, enabling you to print faster.

-- Type 1 fonts are compatible with Adobe Type Manager (ATM), which creates smooth display at any point size using the Type 1 outline font file.

-- Type 1 fonts are compatible with Adobe Type Reunion, which organizes fonts by family in application font menus.

-- Type 1 fonts usually require less printer memory and download faster than Type 3 fonts.

Type 3 Fonts

Type 3 fonts contain character shapes defined by standard PostScript commands, including the BuildGlyph or BuildChar values. Type 3 fonts offer the following advantages:

-- The character shapes are defined using ordinary PostScript language routines, so they are easy to create.

-- You can create support characters that are described using complex composite characters, gray strokes, and gray fills.

Distinguishing Type 1 from Type 3 Fonts

You can distinguish between Type 1 and Type 3 fonts by comparing font file icons and on-screen appearance, checking the font file's PostScript code in a text editor, or checking the font file's resource fork using a resource-editing application (for example, ResEdit).

Comparing Font Icons

Open the folder containing the font's outline file (for example, the System Folder: Fonts folder). View the files by icon by choosing View > By Icon. An Adobe Type 1 font file icon appears as a hollow capital letter "A" on a background of horizontal lines. Type 3, TrueType, and Type 1 font files from a vendor other than Adobe have different icons.

Comparing On-Screen Appearance

With ATM active, open an application, type some text and apply a font size that doesn't have a corresponding bitmap (screen) font installed (for example, 73 point), or view the font at a high magnification (for example, 400%). Because ATM smooths only Type 1 fonts, Type 3 fonts will appear jagged (that is, bitmapped).

Checking a Font File's PostScript Code

Open the font's outline file in a text editor (for example, Microsoft Word). If the open file contains no text, the font is a Type 1 font. If the file contains text (that is, PostScript code), search for the first occurrence of "FontType." If the font type is "3 def," the font is a Type 3 font.

Checking a Font File's Resource Fork

Open the font's outline file in a resource editor (for example, ResEdit). Type 1 font files contain a large amount of font data in the Resource fork. Type 3 font files contain most of their font data in the Data fork, so Type 3 font files contain only a small amount of data (for example, the POST resource) in the Resource fork.

Disclaimer: Adobe doesn't support resource editors and provides this information as a guideline only. Experience using a resource editor is highly recommended to prevent the chance of removing any resource from a file. Always make a backup copy before opening the original font file in the resource editor.