Two PDFs can look identical on screen and behave completely differently. One has crisp vector text that prints at any size; the other is a stack of JPEG images. Knowing what's actually inside dictates how you compress, archive, and print.
What's Inside a PDF Page
| Content Type | Storage | Resolution-Dependent? | Searchable? |
|---|---|---|---|
| Vector text | Font + position references | No — sharp at any zoom | Yes |
| Vector graphics | Paths, fills, strokes | No | N/A |
| Embedded JPEG photos | DCT-compressed bitmap | Yes | No |
| Embedded JPEG2000 | Wavelet-compressed bitmap | Yes | No |
| Scanned page | One full-page bitmap | Yes — pixelates on zoom | Only with OCR text layer |
| Transparency groups | Vector + alpha blends | Mixed | Yes (text inside) |
When to Rasterize
Rasterizing collapses everything to pixels. You lose searchability, accessibility, and editability — but you gain absolute visual fidelity, no font substitution risk, no transparency issues, and a guarantee that the recipient cannot extract or alter content as text.
- Final-stage approvals: "what you see is what gets printed."
- Legal exhibits: capture the document state without giving away searchable text.
- Older RIPs: some print pipelines mishandle live transparency; flattening to raster avoids it.
- Embedded fonts you can't license: rasterize pages with the problematic font to keep the look.
When to Keep Vector
- Long-term archives — vector text remains crisp at any future zoom, font substitution aside.
- Anything searchable or screen-reader accessible — raster pages need OCR to be searchable.
- Small file sizes for text-heavy documents — vector text often compresses to a few KB per page.
- Documents that may be edited later.
Choosing Resolution
When you do rasterize, pick DPI based on the finest detail you must preserve. 300 DPI is the print standard for body text; 600 DPI captures fine hairlines and small caps; 150 DPI is plenty for monitor viewing. Doubling DPI quadruples bitmap size, so don't reach for 1200 DPI without a real reason — it almost never improves perceived quality.
A Quick Rasterize Decision Guide
Faced with a specific file, ask three questions in order:
- Will anyone search, copy, or screen-read the text? If yes, keep it vector — rasterizing destroys the text layer and forces OCR to get it back.
- Are you locking a final proof, fixing a transparency/overprint glitch, or hiding redacted content? If yes, rasterize — a flat bitmap renders identically everywhere and carries no hidden objects.
- Is file size or future editing a priority? Vector wins on both: text-heavy vector pages often compress to a few KB and stay editable.
The common mistake is rasterizing a whole document to “make it safe” when only one page had a problem. Rasterize the minimum, at the lowest DPI that preserves your finest detail.
Convert PDF Pages to Images
Render pages to PNG or JPEG at custom DPI — fully in-browser.
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