I need to restrict the copying and printing of my image files. Please tell me what is the best file format for restricting copying and printing of files?
Well, if you export PDF's from Photoshop, Illustrator or InDesign, you get the 'Security' tab in the export dialog window, where you can set up a password to protect printing and editing the file. Basicly, without the password, a person can only look at the file, but will not be able to print, make edits or extract data from the file.
Aside from this, a person can always copy the file, email it, make screenshots and so on.
You can not, it is a logical fallacy. But i would point out that your solving the wrong problem. Quoting myself
You should not be so concerned with others swiping your designs. What you should be concerned is how to find clients and getting paid. Don't fall into the trap of thinking you're going to lose money at this stage from copying, because even if it happens there's no real way for you to turn it into money.
Only care about money you can actually make. You can look at all the virtual money you've lost, but all that gets you is a bad feeling and is nonconstructive. You're not going to be very efficient in converting that effort into more money. So it's waste of your resources.
The thing is if you allow the computer I am using to read the file then I can copy the file because the file I am viewing is a copy. The media industry has spend hundreds of million or billions to collude with hardware manufacturers to make copy protection possible. Yet the fail each and every time.
They fail because it is in fact impossible to do this with the current technological systems. Now to be honest a technique that might make this feasible has been invented a few years back, in theory, its just that it would require a order of magnitude faster computers because it would slow you down considerable*. So perhaps if you wait 10-20 years.
also don't believe people when they say they can do copy protection. They are either lying, or dont know what they are talking about. Lets take a example:
Even if PDF has a checkbox to do this, it does not actually work. See for it to work it requires that all PDF viewers in the world will respect this flag. This is not possible since there are open source viewers. So stripping the protection of a view only PDF is relatively straight forward.
Now then the only thing that really protects you is the Law, so hone your contracts.
* Given that computers aren't getting orders of magnitudes faster...
There is no such file format.
Include a human readable copyright notice in your image files and on your website or wherever you publish them for a broad audience.
In case of Photographs keep the original camera raw files and never publish them.
Cut at least app. 10-20 pixel wide rows and columns from the image edges for publication so that you can with ease prove with your camera, the raw files and the additional image information that you're the originator.
Publish for viewing lower resolutions in .jpg or other compressed formats.
If you sell or license the images, there will be contracts involved between you and your customers / licensees covering legal uses.
You may embed invisible watermarking into your images to trace them back to where they were copied or printed from.