Lift a signature off a photo or scan of paper and save it as a transparent PNG with soft edges.
Signature Background Remover
Lift a signature off a photo or scan of paper and save it as a transparent PNG with soft edges.
A signature is worth keeping to yourself, so the picture is decoded and the PNG built inside this tab. Neither the photo nor the result is sent anywhere.
A signature cut out by hand always carries the same tell: a pale rectangle of paper that appears the moment the image lands on anything other than white. The answer is not a cleverer eraser but measuring the sheet. How bright the bare paper would be is estimated across the whole picture — brighter by the window, darker where the hand rested — and divided out, one colour channel at a time, which also balances a warm indoor cast so blue ink does not drift towards green. Only the pen survives, with soft anti-aliased edges and the paper un-mixed out of them, so no fringe travels onto a coloured page. Then trim it, thicken a thin ballpoint, pad it and pick a height. The picture is read and the PNG written on your device.
Features
Paper brightness measured across the picture and divided out, so a shadow never becomes a grey box
Automatic threshold plus a sensitivity slider for a faint pen or a heavy marker
Soft edges with the paper un-mixed out of them — no pale fringe on a coloured background
Keep the ink's own colour, or recolour to black, blue or dark blue
Speck removal by size: dust and paper fibres go, the dot of an i stays
Thicken a thin stroke by up to 2 px in half-pixel steps
Padding you choose, and an output height of 600, 300 or 150 px including that padding
Preview on a checkerboard or sitting above a signature line on a mock document
How to use the Signature Background Remover
Sign plain white paper with a dark pen, then photograph or scan it
Drop the picture in and let the paper be measured
Adjust sensitivity, speck size, thickness and padding while watching the preview
Pick the ink colour and height, then download the PNG or copy it
Example
Input
letter-scan.jpg — a signature photographed on a desk under a warm lamp
Output
letter-scan-signature.png — 900 × 260 px, transparent, the pen's own colour
The lamp's yellow cast is balanced out and the paper is simply not there.
Common errors & troubleshooting
The signature came out with grey patches in it. — A pencil or a nearly dry pen sits too close to the paper in brightness. Raise the sensitivity first; if the patches stay, sign again with a darker pen — nothing can separate ink from paper of the same shade.
The stroke broke up into a dotted line. — Lower the speck size — pieces below the setting are being dropped as dust. A fast ballpoint often skips, so thickening by half a pixel joins it back up.
It looks right here but shows a white box in a document. — The file was turned into a JPEG somewhere along the way, and JPEG cannot store transparency. Keep it as PNG all the way to the document.
The edges are hard and stepped rather than smooth. — The picture was already black and white. A fax or a one-bit scan has no grey levels for a soft edge to be built from — rescan in greyscale or colour.
Frequently asked questions
Why does a hand-cut signature show a grey box on a coloured page?
Because the cut-out still contains paper. Even edge pixels that look white are a mix of ink and sheet, and against colour that mix reads as a halo. Measuring the paper and removing it from those pixels is what stops it.
Is it better to photograph the signature or scan it?
Either works. A scan is flatter and needs less correction; a phone photo in even daylight is fine, because the lighting across the sheet is estimated and divided out. Avoid flash, which leaves a bright spot.
Does a signature image count as a legally valid signature?
That depends entirely on the document and the jurisdiction, and this tool makes no claim about it. Many agreements accept a pasted image; others require a certificate-based digital signature. Check what the document asks for.
What size should a signature be for an email footer?
Around 150 px tall is usual — big enough to read, small enough not to dominate the footer. The height you choose includes the padding, so a 150 px choice really does produce a 150 px file.
Why would I thicken the strokes of my own signature?
A fine ballpoint scanned at a low resolution can come out as a one-pixel line that almost vanishes on screen and drops out in print. Half a pixel of growth is often all it needs to look like ink again.
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