PDF Knowledge Hub
In-depth references on how PDF and document technology actually works — file structure, standards, encryption, fonts, images, and text recognition.
| No. | Category | Title | Posted | Length |
|---|---|---|---|---|
| 6 | File format | What's actually inside a PDF file — an anatomy From the %PDF-1.7 you see in a text editor to objects, streams, and the cross-reference table. The internal structure of a PDF, explained for non-developers. | 8 min read | |
| 5 | Standards | PDF/A, PDF/X, PDF/UA — what the letters after the slash mean What you need to know when someone says “submit it as PDF/A”. The archival, print, and accessibility PDF standards: what each guarantees and what each forbids. | 7 min read | |
| 4 | Security | How secure is a PDF password? The truth about the two kinds An open password and a permissions password offer completely different protection. Why “printing disabled” is easily undone, and how to handle documents that genuinely need protecting. | 7 min read | |
| 3 | Fonts | Font embedding and subsetting — why PDFs get heavy or break How fonts travel inside a PDF, the subset compromise, why CJK fonts are a special case, and what font licenses allow. The mechanics of PDF typography in one read. | 7 min read | |
| 2 | Images | Resolution, DPI, and color spaces — the three levers of image quality What “send it at 300dpi” actually means, how pixels relate to DPI, and why RGB and CMYK disagree. The image knowledge document work actually requires. | 7 min read | |
| 1 | Recognition | How OCR reads text — the mechanism and its limits The technology that makes scanned documents searchable: how it works, which documents defeat it, and how far to trust its output. | 7 min read |