Signature Cleaner — Remove Background, Export Transparent PNG
Strip the white background from a signature or chop image and download a transparent PNG ready for PDF overlay.
这个工具是做什么的
Signature Cleaner takes a phone photo or scan of a signature, initial, or company chop and produces a transparent-background PNG you can drop onto any PDF — without uploading the file to a server.
It auto-samples the actual background colour from the four corners of the image, then maps each pixel's distance from that background to an alpha value, with a soft ramp that preserves anti-aliased edges. Tolerance and edge-softness sliders give live-preview control, and an optional auto-trim crops the output to the actual content so it's tight and easy to place.
It pairs naturally with PDF Signer: clean a signature here, then jump straight to PDF Signer to drop it onto a contract, invoice, or form.
使用方法
- Drop a photo or scan of your signature or chop on a clean white-ish background.
- Adjust the Tolerance slider until the background fully drops out.
- Adjust Edge softness so the edges look natural, not jagged.
- Toggle 'Crop to content on export' to trim away empty space.
- Click Download transparent PNG — or jump straight to PDF Signer.
Common use cases
- Turn a phone photo of your signature into an overlay-ready PNG.
- Clean up a scanned company chop for invoices, letters, or receipts.
- Prep an inked initial for HR forms or contracts.
- Get a clean transparent logo from a printed letterhead.
What makes it work
- Auto-sampling four corners avoids one stray ink mark biasing the background colour.
- Distance-based transparency handles off-white scans, beige paper, and coloured backgrounds.
- Soft ramp on edges keeps anti-aliased pixels semi-transparent so the result blends naturally on any background.
- Auto-trim crops the export to the actual content, useful when overlaying on a PDF.
常见问题
Does it only work with white backgrounds?
No. The tool samples the actual background colour from the image's corners, so off-white scans, beige paper, and even coloured backgrounds work — as long as the foreground (the ink) is visibly different from the background.
Will it work for a coloured chop on white paper?
Yes. Red and blue chops on white scan well — the colour distance from white is large, so the chop stays opaque and the paper drops out.
Will the edges look jagged?
The Edge softness slider keeps anti-aliased pixels semi-transparent so the edges blend naturally on whatever background you place the PNG over.
Is my image uploaded anywhere?
No. Cleaning runs entirely in your browser using the Canvas API. The image never leaves your device.
What's the maximum image size?
20 MB. Anything larger usually means a multi-megapixel scan that browsers struggle to keep responsive.
Why is my output PNG smaller than the input?
The 'Crop to content' toggle (on by default) trims away any empty transparent border so the PNG is tight around the actual signature. Disable it to keep the original dimensions.
Can I overlay the result onto a PDF here?
Yes. PDF Signer accepts the transparent PNG directly — there's a one-click link from the result panel.