Covering Up Text in a PDF Isn't the Same as Removing It
If you've ever drawn a black box over a name, account number, or other sensitive detail in a PDF, there's a real chance the information is still there underneath — just hidden, not gone. Here's why that happens, and what genuinely removing something from a PDF actually requires.
A PDF page isn't a photograph
It's easy to assume a PDF page works like a flattened image — that what you see is simply what's there. It usually isn't. Underneath the page you see, a PDF is closer to a set of layered drawing instructions: draw this text here, draw this line there, place this image in that spot. Each of those is typically still a distinct, individually extractable object, even after the page has been rendered and displayed on screen.
What happens when you draw a box over something
When a tool lets you draw a rectangle over sensitive text, in most cases that's exactly what it's doing — adding a new shape object on top of the existing content, in the same way a new layer sits above an older one. The text is visually covered. Structurally, it's still there underneath. Select all the text on that page and copy it, and — depending on the tool and whichever PDF reader opens it — the "hidden" text may paste right through the box drawn over it, or turn up in a search.
What genuine redaction actually requires
There are really only two honest ways to actually remove something from a PDF page, not just hide it:
- Delete the underlying content itself — technically demanding, since it means surgically editing the page's own content stream, not simply drawing something on top of it.
- Rasterize the page — convert the entire page into a flat image, with the sensitive information already removed before that conversion happens. Once it's an image, there's no separate text object left to extract, because there's no text at all anymore — just pixels.
How Foliovex handles this
The PDF editor deliberately offers both of these as genuinely different tools, not two names for the same thing:
- Cover draws a shape over content — fast, fully reversible (undo works normally), useful for something you might reposition or redraw, but not appropriate for anything actually sensitive.
- Redact rasterizes the entire page to an image with the sensitive area already removed before that conversion happens, so there's nothing left underneath to extract, ever.
The honest cost: redacting a page turns it into a flat image, so any genuine text on that page also stops being selectable or searchable afterward. That's not a limitation of how it's built — there's no way to remove one specific piece of content from a page while leaving everything else on it exactly as extractable as it was before.
The one question worth asking
The next time any tool — this one or otherwise — offers to "redact" something, it's worth asking directly: does this actually remove the content, or does it just draw over it? If a tool can't clearly explain the difference, it's safest to assume the worst.