PSFC Home Library Home Index Site Map Contact Us     Search Library
logo   MIT Plasma Science & Fusion Center

Instructions for PSFC Authors: PostScript Type 1 VS. Type 3

Printable view
PSFC Library

PostScript Type 1 and Type 3 Fonts: General Information

Table of Contents

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 (e.g., printed) while maintaining the font's shape at low resolutions. For example, hinting improves the printed appearance of small text printed to a 300dpi 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 user-defined character shapes defined by standard PostScript commands, including the BuildGlyph or BuildChar values. 

Advantages of Type 3  Fonts:
  • 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-editing application, or checking the font file's resource fork using a resource-editing application (e.g., ResEdit). 
Comparing Icons
Open the folder containing the font's outline file (e.g., 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 appear as
different icon. 
Comparing On-Screen Appearance
With ATM active, open an application, type some text and apply a font size that does not have a corresponding bitmap (screen) font installed (e.g., 73 point) or view the font at a high magnification (e.g., 400%). Because ATM smoothes only Type 1 fonts, Type 3 fonts will appear jagged (i.e., bitmapped). 

Checking a Font File's PostScript Code

Open the font's outline file in a text-editing application (e.g., Microsoft Word). If the open file contains no text, the font is a Type 1 font. If the file contains text (i.e., 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-editing application (e.g., 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 (e.g., the POST resource) in 
the Resource fork. 
DISCLAIMER: This procedure is not supported by Adobe Systems Incorporated and is provided only as a guideline. Experience using ResEdit is highly recommended,
since ResEdit can change or remove any resource from any file. Always make a backup copy before opening the original font file in ResEdit.