Flattening - Preview

You can flatten image layers in the appropriate tool (e.g. Photoshop, GIMP, etc.), but not PDF. The process of creating a PDF uses up to five different compression techniques (depending on the content) to make the PDF smaller, but without setting a password on the ability to copy text, images, etc. there is no protection from selecting and copying images from the PDF.

I went back and performed a Print… PDF > Save as PDF from Pages on macOS High Sierra and Mojave. Even Pages '09 v4.3. Those PDF contained multiple images and when opened in Preview, LibreOffice v7.2, and Affinity Designer, in every instance, I could select, copy, and paste the image through the clipboard and into Preview.

In macOS Big Sur, using Pages v11.2, I also created new text and image content. Again, I did the Print… PDF > Save as PDF, and without choosing any security precautions, I got the same result as the second paragraph.

However, on the Save as PDF panel, there is a Security Option… button that takes you to this panel:

That should be self-explanatory and if the originating application provides that Print… PDF sub-menu it can be done there, or in Preview's PDF sub-menu. Once the now protected PDF is opened in Preview, one can open the Inspector (⌘i) and see that there is now a copy restriction on that PDF:

and in practice, when I select an image and attempt to copy it to the Clipboard with a ⌘C, the password prevention kicks in:

If in Preview you open the layered document, then go to File > Print and when the Print dialog opens click on the PDF drop down men (located on the bottom center of the dialog box) and choose Save as PDF, does that do what you want?

MtD

Using Preview, you can export the PDF as a PNG and then export the PNG as a PDF. The text in the resulting PDF will be part of the image of each page.

- Pie Lover

You can give a PDF a password that everyone must enter to open the file. The password is used to encrypt the file.

You can also set a password to manage access to features such as printing, copying text, and adding annotations.

Open Preview for me

Set a password for opening a PDF

You can encrypt a PDF so that it requires a password to open.

1. In the Preview app on your Mac, open a PDF or image.
2. Choose File > Export as PDF, click the Show Details button, then select Encrypt.
3. You can also enter a new name for the PDF if you want to create a password-protected copy and keep the original PDF unencrypted.
4. Type a password, then retype it to verify the password.
5. Click Save.

To remove a password from a PDF that you encrypted, open the PDF and export it again, this time turning off the encryption option.

Set permissions for a PDF

You can password-protect a PDF to manage permissions for printing, copying text and graphics, and more.

1. In the Preview app on your Mac, open a PDF or image.
2. Choose File > Edit Permissions.
3. Do any of the following:

• • To set a password for opening the PDF: Select the Require Password To Open Document checkbox, type a password, then retype it to verify the password.
  • To customize permissions for a PDF: Under Permissions, select the checkbox for any actions—such as printing or adding annotations—that you want to protect with a password. Type a password, retype it to verify the password, then click Apply when you’re finished.

1. Choose File > Save to save the permissions settings.

To remove passwords and permission-based restrictions from a PDF, open the PDF and export it.

See_pee wrote:

This is what I need! I usually export my content as a .PNG and then imbed it as a background. The quality is retained and nothing can be lifted. This is what I want to accomplish!

Are you sure about that?

You specifically asked about "flattening" a PDF. That is a very specific term with multiple meanings to different people. The suggestion to covert the file to PDF is not flattening. That is rasterizing, something completely different. That may be what solves this problem for you, but maybe not.

For context, I found this site that seems to give a fairly precise definition what it means to "flatten" a PDF file: https://pdfpen.com/blog/entry/how-to-flatten-a-pdf/

It says:

Flattening a PDF makes it so that:

1) Interactive elements in PDF forms such as checkboxes, text boxes, radio buttons, drop-down lists are no longer fillable.

2) Annotations become “native text”.

3) Multiple layers of text, images, page numbers, and header styles become one single layer.

I tried your Preview "print to PDF" flattening solution using macOS Big Sur. It behaves exactly like Preview in Monterey. Both effectively do steps 1 and 2 above. Neither do step 3, which is really a different beast altogether and completely unnecessary as far as printing goes.

Can you provide an example of URL that shows what you are talking about. Ideally, it would have both "flattened" and a "non-flattened" versions of a PDF. If you even had one that definitely had a "non-flattened" PDF, that would be really, really helpful here.

It sounds like you are looking for a solution to protect intellectual property by essentially corrupting the original graphics with other graphical elements that have been overlaid. That way, the original graphic elements cannot be extracted from the PDF. I have seen cases where this could be an issue.

However, I see no evidence that Preview ever did that or that Preview is now behaving differently. I even checked Mavericks too. It behaves the same way. It does group the graphics together, but they are still layered. It removes the fill-in capability and merges annotations, but that's all.

Preview isn't a particularly sophisticated PDF tool. That last feature of flattening that you seem to require is an advanced feature that I don't see Preview as ever being able to accomplish. I think you would need a 3rd party tool for this. I also think you were mistaken about Preview's previous capabilities. You always needed a 3rd party tool to do this.

I confess that I only tried this technique with a 2 page document. Perhaps you could experiment to determine if a smaller number of pages would work (say 25 pages). The individual sections can then be merged into a single file from Finder using Create PDF.

Another option, although tedious, would be to import the PNG files into Word (or equivalent) and then Save to PDF from the application (rather than using Preview Export to PDF).

- Pie Lover

See_pee wrote:

Thanks for any ideas!

Sejda has both a free online flattening option and a desktop app. One may suit your needs.

https://www.sejda.com/flatten-pdf

If the creators of the graphic provide you with separate images, then flattening from their T&C's only applies to graphics creation programs where you place their image among other layers. If that is the case, they want you to flatten those layers before exporting the final image content. This is not applicable to word processing or presentation documents that result in the creation of PDF content.

What I have described in my post is the right approach to prevent access to any PDF image content.

The PNG image format is not multipart, so you can only export a single PDF page to a single PNG image. You would have to do this for every page in the PDF which gains you nothing. Adding those images back to Preview and then generating another PDF still does not protect those images from copying without choosing that Security Options button. This approach is a total waste of time when the same protection can be applied to the original PDF.

Excellent / detailed explanation and illustration.

Will bookmark this one :-)

What do you mean 'gone'?

Print to PDF is very much a thing in Monterey.

You're welcome.

This was helpful, thank you!

Note to readers: Be sure to save the PNG file at 320 resolution for best results.