Hidden trace mark (invisible watermark)
Embed an INVISIBLE trace string into an image so you can tell who downloaded/sent a leaked copy. Embed and read right on your machine — the image never leaves it.
Embedding and reading happen on your machine — no image is uploaded to a server
An invisible (forensic) watermark embeds a nearly invisible string of information into Vietnamese ID card (CCCD)/document images — the downloader's name, date, document ID — so if an image leaks, you can read the mark back and find out whose copy it was.
The mark is hidden in the image's frequency coefficients, so it's hard to spot with the naked eye and survives moderate JPEG compression, light resizing, or format changes. All embedding and reading of the mark runs right on your device — your images are never uploaded to a server.
How to embed and read an invisible watermark on images
- 1Select an image
Upload the image you want to protect (JPG/PNG).
- 2Enter the tracer string
Type the downloader's name, date, document ID… then choose the strength.
- 3Embed & download PNG
Click Embed and download the resulting PNG. When needed, use Read hidden mark mode to trace it back.
Frequently asked questions
Does the invisible watermark degrade the image?
It's nearly invisible: the tool only lightly adjusts a few mid-frequency coefficients of the luminance channel, which is hard to notice with the naked eye.
Does the hidden mark send my images anywhere?
Everything runs right in your browser — your files are never uploaded to any server, keeping them completely private.
How durable is the hidden mark?
It survives moderate JPEG compression, light resizing, and format changes. It does NOT withstand screenshots plus heavy cropping/rotation or heavy image filtering — this is a tool for tracing the source of a leak, not absolute protection.