Flatten a PDF Before Sharing: Fields Only or as Image

After filling a form, the values still live in editable fields. Anyone receiving the file can change them, and some viewers show them differently. Flattening fixes the values into the page. Flatten PDF has two modes, and they are very different.

	Form fields only	Everything as image
Field values	Drawn into the page; fields removed	Drawn into a picture of the page
Text selectable / searchable	Yes	No
Document info (title, author)	Kept	Replaced
Our test file	5.6 KB	57 KB

Mode 1: Form fields only (use this normally)

Our sample form had a name field (“Rina Example”), a member number and a ticked checkbox. The result screen said “3 form fields flattened”; pypdf found 0 fields left, and the name and number could still be selected and searched.

Mode 2: Everything as image

This turns each page into a JPEG. At the default 200 DPI our A4 page became one 1653 × 2338 px image with no text at all, and the original document information was replaced. Use it only when a recipient insists that nothing in the file be editable, and keep the original. It does not remove anything hidden in the picture: whatever was visible stays visible.

When you should flatten

• You filled in an application, tax or membership form and are emailing or uploading it: flatten the fields so the values cannot be changed by mistake and look the same in every viewer.
• A portal shows your form as blank, or rejects it: some upload systems ignore form-field values. A flattened copy carries the values as ordinary page content. Our guide to preparing a PDF for an online application covers the other checks portals make.
• You placed a signature image and text with an editor and want them fixed in place: see signing a PDF without printing.

Do not flatten a file you still have to edit. Keep the fillable original and send a flattened copy.

How to check it worked

1. Open the flattened file in your browser or any PDF reader and click on a value: nothing should become editable and there should be no highlighted field boxes.
2. In “Form fields only” mode, try selecting the text you typed. It should still highlight; in “Everything as image” mode it should not.
3. Compare the page with the original to make sure every value, tick and dropdown choice is shown.

What flattening does not do

• It is not redaction. Everything visible stays visible, and in fields-only mode the text is still there to copy. To remove content, follow how to redact a PDF safely.
• It does not hide document information. Fields-only mode keeps title, author and other details; check and clear them with the PDF Metadata Editor (see PDF metadata explained).
• It does not lock the file. Someone can still edit the page content with a PDF editor. If you need to restrict opening, add a password with Protect PDF; our guide on password-protecting a PDF explains the options.
• It changes a digitally signed file. Any change after a certificate-based digital signature makes that signature show as modified. Flatten before signing, not after.

If the image mode makes the file too large to send, compress it afterwards with Compress PDF.

How we tested this

Date	22 October 2026
Environment	Google Chrome 155 (headless) on Linux x86_64, desktop viewport 1280×900, PDFroo build of 22 October 2026
Test file	Fictional 1-page form with full_name, member_no and an agree checkbox (filled)
Results	Form fields only: 3 fields flattened, 0 remaining, text extractable, 5.6 KB. Everything as image: 1 image 1653 × 2338, no extractable text, 57 KB
Network	The browser made no request that carried the file: the only requests during processing were same-origin page prefetches and local blob: URLs.

We checked every output with pypdf, pdfinfo and pdftotext, and recorded every network request the page made while the file was processed. See our tool testing methodology.