If a mark can be taken off, is there any point putting one on?

Yes, but the point is smaller than the marketing around this category suggests. Most reuse is casual — someone needs a picture, yours is there, they take it. A mark makes that thirty seconds of work instead of none, and thirty seconds is usually enough. It does nothing at all against someone who has decided they want your picture specifically.

Is a tiled mark worth the damage it does to the picture?

Sometimes. For a portfolio proof, a client preview, or a print you are showing before payment, yes — the picture is meant to be evaluated, not enjoyed. For a shop listing or anything meant to sell, usually not: the customer you are annoying is the one you wanted.

Does a mark help if my picture is used to train a model?

There is no honest answer to this, and anyone giving you a confident one is guessing. A mark is in the pixels, so it is in whatever is learned from them, but nothing about that constitutes a control over the outcome. Treat it as unknown rather than as a feature.

What actually helps in a dispute?

The original file, with whatever the camera wrote into it, kept somewhere you can produce it. A record of when and where it was first published. Where your country has a registration system and the picture is worth it, a registration. The mark supports a claim; those things are the claim.

What a visible mark actually protects, and what it does not

A visible mark buys friction, attribution and traceability. It does not survive a crop, it does not stop anyone who is trying, and it does not create a right you did not already have.

The claim this page is arguing against

Search for a watermarking tool and you will be told, in one phrasing or another, that a mark keeps your work safe. It does not, and every page on this site is written by people who would rather say so than sell you the comfortable version. What a mark buys is real, and it is narrower than the promise.

The useful way to think about it is as friction, in the ordinary sense: the cost of doing something goes up. Friction works brilliantly against people who were not trying very hard, which is most people, and not at all against people who were, which is the ones you were worried about. Both halves of that sentence matter.

Four things it genuinely does

It raises the cost of casual reuse

Someone building a marketplace listing, a blog post or a slide deck needs a picture and is not going to pay for one. Yours is on the first page of results. Unmarked, it takes one right-click. Marked across the middle, it takes either a visible admission that the picture is yours, or a few minutes with a repair tool and a result that looks like a few minutes with a repair tool. Most people stop.

It carries attribution through a copy chain

Every upload strips metadata. A screenshot destroys it outright. A picture that has been through a social platform, a chat app and a scraper has nothing left in it except pixels — so anything you want to survive that trip has to be drawn into the pixels. A name or a domain in the corner is the only part of a credit that travels.

It changes how the picture reads

An unmarked picture looks unowned, whatever its licence says. A marked one looks claimed. That is a signal to the honest majority rather than a barrier to the dishonest minority, and it is cheap, and it works.

On a document, it makes a copy traceable

Stamping a scan with who it was given to and when is a real practice with a real purpose: if the copy turns up somewhere it should not be, the stamp identifies which copy it was. This is the one case where a visible mark does something a locked file cannot, because the point is not to stop the copy — it is to label it.

Five things it does not do

It does not survive a crop. A mark in a corner is one selection box away from being gone, and there is no setting on this site or any other that changes that. A mark that has to survive a crop has to be somewhere a crop cannot reach, which means across the subject.
It does not defeat a repair tool. Content-aware fill ships in phone photo apps now. Against a small, flat, high-contrast mark on a busy background, it is close to perfect. This is not a secret and a site that sells you a mark should say it.
It does not create copyright. In almost every country the right exists from the moment the picture does, with no mark, no notice and no registration required. Wording on a picture is a claim about a right you already have; it does not enlarge it.
It does not survive as metadata. The credit field this tool can write into a JPG or a PNG is genuinely written, and it is genuinely stripped by most upload pipelines, and anyone can edit it in seconds with free software. Worth having, worth nothing to rely on.
It is not forensic. There is no invisible payload here, no detector, and no service to check a suspect file against. That whole category needs a server, and this site does not have one by design. What you get is what you can see.

The trade nobody states

A mark in a corner is easy to live with and easy to lose. A mark across the subject is hard to lose and hard to live with. There is no third option, and every conversation about watermarking is really a negotiation between those two sentences.

Where each one is the right answer
A corner mark	Anything meant to sell or to be enjoyed: shop listings, portfolio pieces already paid for, editorial pictures where the credit matters more than the control.
A repeated mark	Anything meant to be evaluated rather than used: client proofs, print previews before payment, sample sheets, licensing comps.
A diagonal stamp	A document scan sent to a named recipient, where the stamp names the recipient and the date.
No mark at all	Anything you would rather have seen and shared than controlled. This is a real answer and it is the right one more often than this category admits.

The settings follow from the choice. A corner mark wants a small percentage, a modest inset and enough opacity to read — usually 35 to 50. A repeated mark wants a shallow angle, generous gaps, brick rows and an opacity low enough that the picture is still legible underneath, usually 15 to 25. A stamp wants roughly 20 per cent opacity, a −30° lattice and wording that says something specific.

Why this site does not do the other half

Taking a mark off a picture is a large search category and a legitimate job — people own pictures they marked years ago and have lost the originals. It is not done here. The sibling that does it is pictureeraser.com, deliberately named and deliberately not linked.

The reason is not squeamishness. It is that a site selling you a mark and then selling you its removal has no position at all. Every sentence above about what a mark is worth would be undercut by the tool sitting next to it, and you would be right not to believe any of it. One site, one intent, and the cost of that is a large amount of traffic this site will never see.

What to do instead of relying on the mark

Keep the originals, with whatever the camera wrote into them, somewhere you can produce them. This is the thing that settles arguments.
Publish at the size you need people to see and no larger. A 900-pixel picture is worth much less to take than a 4000-pixel one, and the mark is not what made the difference.
Mark across the subject when being copied genuinely worries you, and accept the cost to the viewing experience instead of pretending there is a setting without one.
Where your country has a registration system and the picture is commercially worth it, register. It is dull, it is cheap relative to the alternative, and it is the only step on this list with legal teeth.
Treat the mark as the cheapest item on this list rather than the only one.

If a mark can be taken off, is there any point putting one on?: Yes, but the point is smaller than the marketing around this category suggests. Most reuse is casual — someone needs a picture, yours is there, they take it. A mark makes that thirty seconds of work instead of none, and thirty seconds is usually enough. It does nothing at all against someone who has decided they want your picture specifically.
Is a tiled mark worth the damage it does to the picture?: Sometimes. For a portfolio proof, a client preview, or a print you are showing before payment, yes — the picture is meant to be evaluated, not enjoyed. For a shop listing or anything meant to sell, usually not: the customer you are annoying is the one you wanted.
Does a mark help if my picture is used to train a model?: There is no honest answer to this, and anyone giving you a confident one is guessing. A mark is in the pixels, so it is in whatever is learned from them, but nothing about that constitutes a control over the outcome. Treat it as unknown rather than as a feature.
What actually helps in a dispute?: The original file, with whatever the camera wrote into it, kept somewhere you can produce it. A record of when and where it was first published. Where your country has a registration system and the picture is worth it, a registration. The mark supports a claim; those things are the claim.