yes and no. If you plan on dropping objects on them and submitting them to the stock companies I wouldn't recommend it since you actually don't own the background. 

thank you for all for your cooperation.. :-)

if I use images taken from wallpaper sites, how do I know if they are covered by copyright? and in any case, how and where can I look for if an image is copyrighted or not? 

thank you for all for your cooperation.. :-)

if I use images taken from wallpaper sites, how do I know if they are covered by copyright? and in any case, how and where can I look for if an image is copyrighted or not? 

Try asking the wallpaper sites, I'm sure if you can find a legit site (which I very much doubt) they would be happy to help. Otherwise, don't waste your time, they all have copyright.

ok, thanks for your answers, but maybe I explained bad, do not misunderstand me, I would just like to know if there is a way to know if and how an image is protected, just not to make mistakes, there is a website or a method where the power to make this type of research? or not?

right, thank you very much.. :-)

My view on "free wallpaper" is that it is exactly that, and nothing more.

It's free to put on your screen as wallpaper.

in order for you to be able to use the wallpaper as your own:

- the original author must have declared it 'public domain' (free for anyone to use, any way they wish, including for profit)
- or it has to have been created long enough ago such that the copyright expired (75 years?)
- or no one in the world must be claiming any rights to the work (which makes it default public domain), which is very difficult to prove

the only way to determine if the wallpaper is public domain is to use the image search feature to search for all instances of the image, and see if he can track down the original author and see if the original author has declared it as public domain.

every country has different copyright laws. in many if not most countries, you can use almost any work because there is no copyright protection. if your country is not a signatory to the Bern convention or WIPO Copyright Treaty, you can do whatever you want with other people's copyrighted works.

and being a member of an international treaty doesn't automatically grant you copyright protection, it just guarantees you copyright protection if you file in a member country and pay the fee.

technically, if you live in the US, your work is ONLY copyrighted in the US unless you file the copyright and pay the WIPO fee, which only makes it protected in the WIPO signatory nations, which is a fraction of the world.