I have a problem in data leakage prevention: users can copy the documents on SharePoint by take many pictures (using a camera).
Please help me to prevent that user's action.
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As soon as a user can open/display a document, you're usually out of control. Digital Rights Management (DRM) might help to prevent some leakage, but sooner or later these are bypassed, anyway. If something is displayed, usually it can be copied somehow.
You cannot prevent a user from taking "physical" (maybe let's better call them "analog") copies (like the taking-pictures-from-screen example you proposed) but using physical security measures: lock access to dedicated rooms with entrance control (so nobody can bring cameras). Compare with DRM for movies failing, as soon as somebody pulls a video camera and simply records it again.
Even if there'd be some technology to prevent cameras taking pictures from standard computer screens (I doubt so), the user could still take notes and manually copy contents as soon as he's able to read it.
Sorry, that's literally impossible to prevent, unless you post security guards next to all computers who monitor your users' behaviour. This is known as the analog hole.
Adding to Jen Erat's answer, it is important that you classify your documents, so that you can have more control over the vital documents that cannot leak.
Then you could put them on a controlled room with monitored access and no cameras or phones allowed.
Now if you are talking, for example, about some documents you sell for some users, and want to prevent leakage from these users, then I don't think there's much you can do about it.
What you can do in this case is increase the effort one must apply to leak the document, without being discovered, like placing a watermark across the whole document or sumthing. Then if there are any leaks, you can identify which user did it, and impose legal obligations to him. To do so without being discovered the user would need to remove all watermarks...