How to use copyrighted images in an article? I have developed an educational software in which I make use of some copyrighted images, for example from Disney, and am now writing an article about it.

How should I reference or cite that those images are copyrighted? Should I put it on a footnote or just blur the images inside the article?

I would not like to have problems of an article rejection because of that.
The images are copyrighted. You are not allowed to put it in the article unless you obtain an explicit (and preferably written) permission by the copyright holder to use it there. If you obtained a permission to use it for research and you would like to consider it a permission to publish it in an article, you better consult a lawyer, but the odds are that you can't do that. As well, do not forget to check whether the journal's copyright transfer is not conflicting with the permission you obtain from the picture's copyright holder. You'll very likely need an exception from the Editor to be allowed to use the image.

To see that this is an issue, remember that the usage of the famous Lenna picture led to legal complaints raised by PlayBoy who is the copyright holder. They decided to cancel the complaints, but it was just their choice. (Source: http://www.cs.cmu.edu/~chuck/lennapg/lenna.shtml)