Can Dogs See Colors?

My 10 year old niece asked me yesterday if dogs see only black & white. I told her that dogs are color-blind but I wasn't sure if they were restricted to the black & white color spectrum.  I looked into this a little more and found an article on Psychology Today which I found interesting and wanted to share with everyone:

According to this article, dogs can only see shades of blue to yellow so it is hard from distinguish a red toy against green grass. Very interesting!