Cid Font F1 F2 F3 F4: Repack
CID (Character Identifier) fonts are a method of encoding font data designed to support large and complex character sets, such as those used in East Asian (CJK) languages, which often exceed the standard character limits of Western fonts. When you encounter "CIDFont+F1," it is not the name of a specific commercial typeface you can download. Instead, it is a placeholder created by exporting software (like Adobe InDesign or various online PDF converters) when it fails to correctly decode or embed the original font. Why F1, F2, F3, and F4?
- CID stands for Character ID.
- CID-keyed fonts were created by Adobe to efficiently handle very large glyph collections (e.g., Chinese), by mapping character codes to CIDs, and CIDs to glyphs in a single font file.
- CID-keyed fonts come in PostScript Type 0 (CID Type 0 / CFF-based) and OpenType/CFF flavors (CID-keyed OpenType). They let you reference many thousands of glyphs without the limitations of older single-byte encodings.
- The CIDFont: This is the glyph data (the shapes). It doesn't care about "A" or "B"; it just knows "Character ID 001", "Character ID 002", etc.
- The CMap (Character Map): This acts as the translator. It tells the system, "When the user types 'A', show Character ID 001."
- Extract embedded font. Use fontTools’ pyftsubset to keep only used Unicode ranges or glyphs, output as a new CFF or OpenType file, and re-embed in PDF. Verify CMap correctness for selectable text.
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