In general pictures you take can be used as a basis for art. However with celebrities, getting permission is a good idea. Otherwise you may be unwittingly exploiting their rights to control their publicity.

On the US website from CafePress.com, an extensive discussion on this topic is posted. Cafepress.com reproduces items that are based on images posted by artists for commercial purposes. You might find it useful. Here is the link.

http://www.cafepress.com/cp/info/help/law.aspx
and on that page you will see this Q & A: (True and false format)

Assumption:
I took the photo, so I can use it however I want.
FALSE.

Simply taking a photo of a person, company, brand, logo or the like does not afford you the right to sell merchandise featuring that photograph. There are two distinct intellectual property rights in a photograph:

1. the rights in the photograph itself and
2. the rights in the subject of the picture, such as the product or person shown in it.

For example, if you take a photo of a celebrity, you only own the rights to the photo, but not the right to use the photo of a celebrity for merchandise sale. In order to sell merchandise with the image, you will need to obtain explicit permission from the celebrity.

From the Canadian perspective, there is a good link from the Federal Government as a legal guideline for Museums. http://www.chin.gc.ca/English/Intellectual_Property/Licensing_Images/publicity.html

From that link it says: "In Canadian law, some legal protection is available in situations where there is an exploitation. In the case of living persons, written releases should be obtained from persons whose images are used commercially."

If the photos are yours, there should not be any issue in basing an art image on the photo. If not, then you would need the photographer's permission. If the photos were taken at a concert or other venue where cameras were not permitted, then do not use those photos.

This article first appeared in the My Art News Letter #22