Bake form fields into the page — or rasterize the whole file print-shop flat
Field values become page content. Text stays selectable and searchable; file size barely changes. Comment annotations are left as-is.
Every page becomes an image at your chosen DPI. Fields, annotations, layers — all flattened to pixels. Nothing left to edit; text no longer searchable.
| In your PDF | Forms mode | Press mode (raster) |
|---|---|---|
| Filled form fields | Baked into the page | Baked (as pixels) |
| Empty form fields | Removed | Removed |
| Comment annotations | Kept as annotations | Flattened to pixels |
| Layers (optional content) | Kept | Baked as displayed |
| Text stays selectable | Yes | No — pages are images |
| Typical file size | About the same | Usually larger |
| Page size | Points (PDF units) | 150 DPI | 200 DPI | 300 DPI |
|---|---|---|---|---|
| US Letter (8.5×11") | 612×792 | 1275×1650 | 1700×2200 | 2550×3300 |
| A4 (210×297 mm) | 595×842 | 1240×1754 | 1654×2339 | 2480×3508 |
| US Legal (8.5×14") | 612×1008 | 1275×2100 | 1700×2800 | 2550×4200 |
PDF pages are measured in points (72 per inch), so rasterizing multiplies by DPI÷72 — 150÷72 ≈ 2.08×. 200 DPI is the sweet spot for most print-shop uploads; 300 DPI is press quality.
A "filled" PDF form is two layers: the page, plus a set of interactive field objects floating on top, each holding its current value and a little widget for editing it. Flattening in Forms mode draws each field's value directly into the page content and deletes the field objects — the words you see don't move, but there's nothing left to click, tab into, or accidentally clear. Press mode is blunter: render every page to an image with pdf.js, then assemble a fresh PDF from those images with pdf-lib. Whatever a viewer displays — fields, sticky notes, visible layers — is what the ink becomes, and nothing interactive survives.
Take a one-page form with two fields: a name text box filled with "STUART FLEMING" and an "I agree" checkbox. Forms mode opens it with pdf-lib, flattens, saves — reload the output and the form reports 0 fields (down from 2), while the name prints in the same spot it occupied before. Press mode at 150 DPI on a US Letter page (612×792 points) renders each page to 1275×1650 pixels — 612 × 150⁄72 = 1275 — and the rebuilt file's page is still 612×792 points in size, just made of one image instead of text and fields. Either way, the original file on your disk is untouched; you get a new -flattened.pdf.
It bakes the editable parts of the document into the page itself. Form fields stop being fields — their current values get drawn as ordinary page content — and in the rasterizing mode, annotations and layers become pixels too. What the reader sees barely changes; what the reader can change is what disappears.
Their imposition and variable-data software re-processes files, and interactive elements are where that pipeline breaks: fields can shift, render differently, or carry data between jobs. A flattened file is inert ink — it prints exactly what's on the page with nothing left to interpret.
No — that's the opposite of what it's for. Flattening draws your filled values onto the page permanently and then removes the field machinery around them. The words stay; the little boxes you typed them into stop existing. Keep the original if you might need to edit the answers later.
No. Flattening is one-way by design — the field structure is removed from the file, not hidden. Treat it like printing: keep the original file with live fields, and flatten a copy for whoever asked for it.
Forms mode when you only need fields baked in — text stays selectable and searchable, and the file stays small. Press mode (rasterize) when a print shop or portal demands a fully flat file: everything becomes an image at 150–300 DPI, nothing is editable or searchable, and the file usually gets bigger.
Forms mode: barely moves — you're swapping field objects for drawn text. Raster mode: usually grows, because each page becomes an image (a US Letter page at 200 DPI is about 1700×2200 pixels). If size is the goal, flatten first, then run the file through a PDF compressor.