mutool info broken.pdf | grep -i cidfont Look for:
This comprehensive article breaks down everything you need to know about CIDFontF1 through CIDFontF6, their roles in composite fonts, and the latest updates to their handling in modern PDF renderers. Before understanding F1–F6, we must understand the CID (Character Identifier) system. cidfontf1 f2 f3 f4 f5 f6 updated
Here are the key updates as of recent years: Older PDFs often used "base 14" CIDFonts common to Acrobat. The updated standard requires that for cidfontf1 through cidfontf6 , the font program ( /FontDescriptor → /FontFile3 ) must be fully embedded, not just referenced. This improves portability across devices. Update 2: TrueType CIDFonts (CIDFontType2) Previously, CIDFontType2 was secondary. The update clarifies that any cidfontf4 or cidfontf5 can now use TrueType outlines directly via a /CIDToGIDMap . This is critical for vertical writing in Japanese. Update 3: Adobe-Japan1-6 and Other Supplements If you open a PDF with cidfontf2 and inspect /CIDSystemInfo , an updated PDF (post-2023) will likely show Supplement 6 (for Japan1) or Supplement 5 (for GB1). These supplements add thousands of new characters (e.g., new Kanji from the JIS X 0213 standard). Update 4: Improved Fallback Logic Modern readers (Chrome’s PDFium, Mozilla’s pdf.js) have updated how they substitute missing cidfontf3 fonts. The new algorithm looks at /CIDSystemInfo more strictly, preventing incorrect glyph substitution (e.g., using Korean fonts for Chinese text). Common Scenarios Where You Encounter CIDFontF1–F6 Scenario A: PDF/A Archiving When converting a document to PDF/A (ISO 19005), all fonts must be embedded. You will see: mutool info broken
Unlike simple fonts (Type 1 or TrueType) that use an 8-bit encoding (max 256 characters), CID-keyed fonts are designed for large character sets—essential for languages like Chinese, Japanese, and Korean (CJK). A CIDFont is a type of composite font that maps a CID (an integer) to a glyph description. The updated standard requires that for cidfontf1 through
If you have ever dug into the inner workings of a PDF file—whether for digital forensics, document engineering, or troubleshooting a corrupted print job—you have likely stumbled upon a cryptic string: cidfontf1 , cidfontf2 , cidfontf3 , cidfontf4 , cidfontf5 , or cidfontf6 .
In PDF syntax, a CIDFont dictionary is a subtype of the Font dictionary. When you see CIDFontType0 or CIDFontType2 , you are looking at a placeholder for thousands of possible glyphs. The labels F1 , F2 , etc., are not standard font names like "Arial" or "Times New Roman". Instead, they are font resource name tags automatically generated by PDF creation libraries (such as iText, Apache PDFBox, or Adobe Acrobat’s own engine).