About this tool
A watermark marks an image with its source or owner to discourage unauthorised use. Publish a photo and it tends to spread without attribution; a name or a web address embedded in the picture travels with it. It is not a lock — anyone determined can remove one. What it does is make casual copying inconvenient, and tell people who want to use the image properly where it came from.
Two kinds are available here. A visible text watermark places your name or address over the picture. An invisible watermark hides information in the least significant bits of the pixel data — LSB steganography — so the result is indistinguishable from the original by eye, and can be recovered later through Filter > Digimarc > Read Watermark. Use the second when you do not want to spoil the look of the image. Your image is never uploaded. Editing and saving both happen inside your browser, so you can open files you would not want to hand to a server — photos with faces in them, internal documents, anything sensitive.
How to use
- Click "Pick an image & start" to open a file.
- For a visible watermark, type the text you want to embed — a name, a site address, a year.
- Set position, size and opacity. Somewhere unimportant in the frame, at reduced opacity, interferes least.
- For an invisible watermark, open Filter > Digimarc and enter the text to hide. Read it back later from the same menu.
- Save via File > Export, and keep an unwatermarked original separately.
Frequently asked questions
- Where should the watermark go?
- Small and in a corner interferes least but is trivially cropped out. Large and central is hard to remove but hard to look past. For images you are genuinely worried about, a low-opacity mark spread across the subject is the usual compromise: removing it means cutting into the part of the picture people actually want.
- How does an invisible watermark work?
- It alters only the last digit of the numbers describing each pixel colour — a change of one step, far below what the eye can detect. Reading those last digits back reconstructs the hidden text. Filter > Digimarc > Read Watermark does that for you.
- How robust is an invisible watermark?
- It survives a straight copy of the file, but not much handling. Re-saving as JPEG or changing the dimensions recalculates those last digits and destroys the hidden data. Treat it as confirmation of ownership on an untouched original rather than a tracking mechanism, and pair it with a visible mark if the claim needs to be obvious.
- Can a watermark be removed later?
- Not from a saved file. A visible watermark overwrites the pixels underneath, and the original content is not retained. This is exactly why you keep an unwatermarked master. During the session, Ctrl+Z still works.
- What opacity works best?
- Somewhere around 30-50%. Readable without dominating the picture. Use dark text on bright images and light text on dark ones so the mark holds up wherever the image ends up, and a soft shadow behind the text helps on busy backgrounds.
- Can I watermark a batch of images?
- Automate > Batch will export many files in one pass. Bear in mind that one fixed position will not suit every composition, so review anything important individually.
- Does watermarking degrade the image?
- Only the area the mark covers changes; the rest is untouched. What can bite you is saving as low-quality JPEG afterwards, which produces fringing around the letterforms. Raise the quality a little, or save as PNG or WebP, for images containing text.
- Does a watermark have legal force?
- The watermark itself does not create any right — copyright exists from the moment of creation. What it does is make it harder for someone to claim they did not know who made it, and it serves as supporting evidence in a dispute. For an actual legal question, talk to a professional.