Cid Font F1 Family | ESSENTIAL |

Key Interpretation

• CID Fonts: A font format developed by Adobe for handling large character sets (e.g., Chinese, Japanese, Korean – CJK). Unlike simple fonts (limited to 256 glyphs), CID fonts can support thousands of characters.
• F1: In a PDF or PostScript file, F1 is often a font resource name (a tag) given to a font within that specific document. It does not refer to a standard font family name like "Arial" or "Times New Roman". F1 is simply an internal label.

So "CID font F1 family" generally means: In the current document, the CID-keyed font labeled F1 belongs to a particular font family (e.g., Heisei Mincho, Kozuka Gothic, SimSun, etc.).

What is a CID Font?

To understand the "F1 Family," one must first understand CIDs.

The acronym stands for Character Identifier. In the early days of digital type (the 80s and early 90s), standard font formats like PostScript Type 1 were designed primarily for Western languages. These languages generally require a limited set of characters (a standard alphabet, numbers, and punctuation—usually under 256 glyphs).

However, when software developers attempted to adapt these systems for Asian languages—such as Chinese, Japanese, and Korean (CJK)—the system broke. These languages require thousands, sometimes tens of thousands, of unique characters. The existing font architecture simply couldn't handle that many "slots." cid font f1 family

In 1993, Adobe introduced the CID-keyed font format to solve this problem. Instead of giving every character a specific name (like "A" or "B"), CID fonts assign each character a unique number (a CID). This creates a massive, indexed library of glyphs that can be accessed efficiently, regardless of the size of the character set.

Step 3: Remap via FontConfig (Linux/GS)

Create a custom cidfmap file for Ghostscript:

/CIDFont/F1Family /NotoSansCJK-Regular ;
/CIDFont/F1Family /SourceHanSans-Regular ;

Then run:

gs -sFONTMAP=/path/to/cidfmap input.pdf

Problem 3: How to Identify if a PDF uses the F1 Family

Run the following command in your terminal (Linux/macOS) or command prompt (Windows with pdftools installed):

pdffonts your_document.pdf

Look for a line where the "font" column reads something like F1 or Arial+F1. The "type" column will show CID TrueType or CID Type 0.

Part 4: Technical Anatomy of an F1 CID Font

If you open a PDF in a text editor (or use a tool like pdftk or qpdf to uncompress the stream), a CID Font F1 definition looks similar to this: Key Interpretation

/F1 <<
  /Type /Font
  /Subtype /CIDFontType2
  /BaseFont /F1
  /CIDSystemInfo <<
    /Registry (Adobe)
    /Ordering (Identity)
    /Supplement 0
  >>
  /FontDescriptor /F1Desc
  /DW 1000
  /W [ 0 [ 500 500 500 ... ] ]
>>

Key observations:

• CIDFontType2: This indicates a TrueType-based CID font (Type0 is PostScript-based).
• Registry/Ordering (Adobe/Identity): This is a universal CID mapping used for Unicode. "F1" often pairs with Identity-H (horizontal) or Identity-V (vertical) CMaps.
• DW (Default Width): Defines the advance width of glyphs not specified in the width array.

The "F1 Family" lacks typographic frills: no kerning tables, no ligatures, and often no hinting. It is a utilitarian fallback.