Convert a Stamp to Grayscale
Turn a coloured seal into clean grayscale for mono printing, archival scans, and documents that must not look like an original.
Free preview · No signup · ~10 seconds
Drop a coloured stamp — image or PDF
PNG, JPG, WebP, SVG or a 1-page PDF — up to 20 MB
Runs entirely in your browser. Your image is never uploaded.
Why a seal is converted to grey
Luminance, not an average
Each pixel is weighted by how bright the eye reads its channels rather than averaging them. That matters especially for red seals: a naive average turns a vivid red into a muddy mid-grey, while proper weighting keeps it dark and legible.
Mono printing and photocopying
Office printers convert colour to grey with whatever algorithm the driver happens to use, and the result is often flatter than it should be. Converting deliberately means you decide how the seal reproduces rather than the print queue.
Marking a document as a copy
A grey seal is visibly not an original impression, which is exactly what some workflows want. It preserves the fact that a document was stamped while signalling that this particular file is a duplicate.
Transparency is untouched
Only colour is removed. A transparent stamp PNG stays transparent and keeps its exact silhouette, so it still drops cleanly onto any background.
Grayscale versus threshold
Grayscale keeps every shade between black and white, so the pressed texture survives. Thresholding removes the middle entirely and leaves two tones. Use grayscale for viewing and printing, threshold for cutting a die.
How to convert a stamp to grayscale
Upload the stamp
Drop in the coloured seal, transparent or on paper. Scanned to PDF instead? A single-page PDF works as well — page 1 is turned into an image in your browser.
The result appears immediately
Conversion runs the moment the image loads. There is nothing to configure.
Download
Take a free preview, or download the full-resolution file with one credit.
Where a grey seal is the right choice
Mono printing
Control how the seal reproduces instead of leaving it to the printer driver.
Marking copies
Signal that a stamped document is a duplicate rather than the original.
Archival scans
Store a consistent grey version alongside the colour original.
Documents printed in one ink
Prepare a seal for newsletters and forms produced without colour.
Or just ask
Describe the edit in your own words
Type what you want changed and the assistant does it on the canvas — each step lands as a layer you can reopen, so nothing it does is baked in.
No edits yet.
Frequently Asked Questions
Related Tools
Guides worth reading
How to Fix Blurry or Fringed Edges on a Transparent PNG
Why your transparent PNG has a white halo, a grey fringe or soft edges — the four real causes, how to tell them apart in seconds, and the fix for each.
SVG vs PNG for Logos: Which File Do You Actually Need?
What SVG and PNG really are, where each one wins, why your developer keeps asking for the SVG, and the three files that cover almost every request.
How to Make a Duotone Image in Figma (Building One From Blend Modes)
Figma has no duotone effect. You assemble one from a desaturated image and two blended rectangles — here is the layer stack, the order that matters, and an honest account of what it costs to maintain.
Convert your stamp to grayscale
Upload and download a clean grey version of the seal.