The fairness of it is at least questionable. Even when it might be legal, the use of the images without mentioning the source of it is unacceptable ethically. Even such a simple image can be considered as a creative act, so using it without mention of the original source can be considered as plagiarism.
Would you please further inspect this suspicious article for other facts of possible plagiarism (usually, the Web search on phrases and code fragments tells the tale) and report it here: http://www.codeproject.com/Forums/1652005/Spam-Watch.aspx
Not that that watch forum is not just spam watch; it's for reporting of all kinds of abuse; and plagiarizing should be considered as one of the worst kinds if misconduct.