How to Remove the Background From a Signature

You sign a piece of paper, scan it or photograph it, and drop the image onto a contract. What lands is not your signature: it is your signature inside a white rectangle, sitting on top of the printed line, the date beside it and whatever else was underneath.

The fix is to make the paper transparent and keep the ink. This is how to do that on PDFRaw, what the cut-out is actually doing, when it will decline to do it, and how to take a photo that gives it something to work with.

Why there is a box around it in the first place

A photograph of a signature is a rectangle of pixels. Every one of them has a colour, including the thousands that are just paper, and paper photographs as an opaque off-white rather than as nothing. Placed on a document, that rectangle behaves exactly like a sticker: it covers what it overlaps.

A signature drawn or typed in the editor never has this problem, because it is created with transparency already. It is only the uploaded route that brings paper along with the ink, and it is the route most people want, because a signature you actually sign looks like one. The same applies to anything else you paste onto a page from a photograph, which is why annotating a PDF with a scanned mark runs into it too.

Two workarounds are worth naming so you can skip them. Cropping tighter does not help, since the crop is still a rectangle. Nudging the image so the box misses the printed line works until the line moves, and on a form that reflows at all it is a trap.

Doing it, in about a minute

Open your document in the PDF editor, or go straight to Sign PDF if signing is the whole job.
Click Sign, then the Upload tab, alongside Draw and Type.
Choose a PNG or JPEG of your signature. The zone reads "Preparing image" while it is being read, which on a full-size scan takes a moment.
Two previews appear: Original and Background removed. The cut-out is selected already, because it is what almost everyone wants; click Original if you prefer the paper.
Leave "Save for next time" ticked if you will sign again, then confirm.
The signature lands on the page you are looking at, centred and already selected, so you can drag it onto the line and resize it from the corner.

Only PNG and JPEG are accepted. An iPhone photo saved as HEIC needs converting to JPEG first, which takes a few seconds and is the single most common reason the file picker rejects something.

What the cut-out actually does

A crude background remover picks everything lighter than some threshold and deletes it. That gives you a hard-edged signature with stair-stepped strokes, because the edge of real ink is not a clean boundary: it fades into the paper across a few pixels, and those in-between pixels are what make a stroke look drawn rather than drawn by a computer.

So the paper colour is measured first, as the median of a two-pixel ring around the edge of the image. Median rather than average, so one dark corner or a stray speck cannot drag the reading. Then every pixel is made transparent in proportion to how close its brightness is to that paper colour: fully transparent at the paper's own brightness, fully opaque well below it, and a smooth ramp in between. The soft edges survive, which is the entire point.

One more step matters and is easy to miss. A grey pixel at the edge of a stroke is not grey ink; it is your ink blended with the paper behind it. Make it transparent while leaving it grey and every stroke gets a pale halo around it. So the ink's own colour is recovered from the blend before the transparency is applied, which is why blue ink stays blue instead of going chalky at the edges. The result is always saved as a PNG, because JPEG has no transparency to save.

When the option is not offered at all

Sometimes you will upload an image and see only one preview. That is deliberate. The cut-out is offered only when the picture really is ink on paper, and there are three cases where it is not:

The image already has transparency. Somebody has cut it out already, and offering to do it again is noise.
The border is dark. If the ring around the edge is not light, there is no paper there to measure, and guessing would eat half the image.
The border is busy. If a good share of that ring is much darker than the rest of it, the picture runs right to its own edges: a photo cropped tight to a stamp, or a signature on something patterned. Again, no measurable paper.

In all three you get the original and nothing else, which is the right answer. A confident wrong cut-out on a signature you are about to put on a contract is worse than no cut-out, and it is the kind of failure you only notice after sending.

How to make a scan worth cutting out

Almost everything that goes wrong here is decided before the upload. The rules are short:

Plain white paper, dark ink. Lined or squared paper puts the lines into the cut-out with your signature, because they are darker than the page they sit on.
Leave a margin. The paper colour is read from the border of the image, so a photo cropped right to the ink has nothing to sample and will fall back to the original.
Flat, even light. A hard shadow across one half reads as a different paper colour from the other half. Daylight near a window beats an overhead lamp.
Do not photograph at an angle. Perspective makes one edge darker than the other, which is the same problem as the shadow.
Do not worry about resolution. A large scan is reduced on the way in, and a signature on a page never needs more than a few hundred pixels across.

That last one is worth expanding, because it used to be the thing that made this feel broken. A flatbed scan arrives at several megapixels, and an image that size then rides along in every undo step, every autosaved draft and every save of the signature itself. Uploads are now reduced once, on the way in, before any of that happens. A scan is shrunk to at most 800 pixels on its long side and re-encoded until it comes in under a few hundred kilobytes, and an image that is already small is left alone rather than re-encoded, since re-encoding a small PNG usually makes it bigger. If your documents are running heavy for other reasons, why is my PDF so large covers the rest.

After you confirm, and doing the same with a stamp

The signature is placed the moment you confirm: centred on the page in view, selected, with the Select tool already armed so your next drag moves it rather than drawing something. Place it again and the copies cascade instead of landing exactly on top of each other.

If "Save for next time" was ticked it is stored afterwards, so a slow save never holds up the placement. When the save does fail, the editor says so in its own banner with the signature still sitting on the page, rather than reporting it inside a dialog that has already closed.

The Stamp dialog has the same Upload tab and the same background removal, for a scan of a real company stamp, with its own saved list. Signatures and stamps are stored separately, so a run of saved stamps cannot push your signatures out.

What none of this settles is whether the signature counts. A cut-out image of your handwriting is an image, and which signature actually holds up is the post for that question. If you are signing a form rather than a contract, the official forms catalog fills the fields first, Fill PDF handles a flat scan with no real fields in it, and How to sign a PDF online covers the rest of the flow.

Frequently asked questions

What image formats can I upload as a signature?

PNG and JPEG. An iPhone photo saved as HEIC has to be converted to JPEG first. Anything else is refused at the file picker with a message rather than silently failing.

Why is there no "Background removed" option on my upload?

Because the image is not ink on light paper as far as the measurement can tell: it already carries transparency, or its border is dark, or the border is busy enough that no paper colour can be read. You get the original on its own instead of a bad cut-out.

Will the cut-out give my signature jagged edges?

No. Pixels are made transparent in proportion to how close they are to the paper colour rather than by a hard threshold, so the soft edges of real ink survive. The ink colour is also unmixed from the paper it was blended with, which is what stops a pale halo forming around each stroke.

Does a big scan slow the editor down?

Not any more. Uploads are reduced once as they come in, down to at most 800 pixels on the long side, so the full-resolution file never reaches the undo history, the autosaved draft or the saved signature list.

Can I do this with a company stamp too?

Yes. The Stamp dialog has the same Upload tab with the same background removal, and stamps are saved in their own list so they cannot crowd out your signatures.

Is the cut-out image saved anywhere?

Only if you leave "Save for next time" ticked. It is then kept against your browser session, and against your account as well if you are signed in, so no account is needed to reuse one. The placement happens first either way, so a failed save leaves the signature on the page and reports the problem in the editor.