If you posted an image that belonged to you on Wikimedia, would you want someone to use it without your permission?
It's ok to use an image according to its license. But if you cannot find the license, what then?
I look for public domain images and modify them to my purpose. http://www.public-domain-image.com/
But there are times when you can use a copywritten image - without modification. It's called 'fair use' and allows writers to use product images to promote the product. It is still better to get permission though. Just email the owner if you can find him or her.
Also, be sure to check with HubPages Learning Center ( http://hubpages.com/community/Learning-Center-Pict... ) to find the correct way to use photos and images in a hub.