Make your signature background transparent

A signature with a white box behind it covers whatever it lands on. Here's how to end up with one that has nothing behind it but your ink.

Why a photo of a signature carries a box

A photo is a rectangle, and every pixel in it has a colour — the paper included. Drop that straight onto a page and the paper comes too, as a pale patch around your name. On a white page you may not notice. On a letterhead, a tinted form, or over a line of the contract you are signing, you will.

What you want instead is an image where the paper is gone and only the ink is left. Stamp Document makes that cut for you, and it is worth knowing what it is doing so you can hand it a photo it can work with.

Step 1 — Sign on white paper

Sign once on a clean sheet of white paper with nothing else on it, and photograph it from straight above in even light. If your phone is easier than your scanner, use the app's own capture: choose No — use my phone, scan the code with your phone's camera, and the photo comes back to the app. You can also sign with your finger on the phone instead of on paper.

Step 2 — Let the app cut the paper away

There is no button for this. As soon as the image is read, the app measures the paper's own colour across the photo — not one fixed white, but the local colour in each part of it — and makes everything at that colour transparent. That is why an off-white sheet and a soft shadow still come out clean. The stroke edges keep their softness without the pale halo a hard cut-out leaves, and the image is trimmed tight to the ink.

Step 3 — Check it on a coloured page

The chequerboard behind the preview is how transparency is drawn: wherever you can see the squares, the page underneath will show through. Read along the strokes for grey fringing, and look at the corners for anything left of the paper. If something is off, drag the selection rectangle on the photo and the cut is made again on the new area, as many times as you need.

The honest test is a coloured page. Put the signature on a letterhead or a tinted form and there should be no rectangle around it, only ink sitting on the page.

Step 4 — Save it as a stamp

Name it, type its Real size on paper — a signature is usually around 50 × 15 mm, and one you signed with your finger on the phone arrives with its size filled in — and click Save stamp. It joins the stamps panel with its transparency intact, one drag away on every document after, and the same cut-out is written into the PDF you export, so nothing you sign over is hidden.

What about a PNG that is already transparent?

Plenty of files are called transparent and still carry a white rectangle: the format changed, the paper never left. Stamp Document reads every image as ink on white paper and makes the cut itself, so an already cut-out PNG goes through the same step as a photo, and you arrive at a clean signature either way. Read the preview before you save, whichever you started from.