If I cite the source of an image, can I use it on my blog? I've heard no. Why is this different than citing research?

Your thought process is right, but your analysis is off. If I want to cite research, I might use a sentence or a paragraph of the research paper and the sorts of people that will be interested in purchasing the research paper will not be appeased by my citation (e.g., they will still go buy it and may even be encouraged to go make the purchase by seeing my citation). When you use the image, you are using the whole image. If you want to put a sentence on your site about the image so that people go look at the image, that would be fine. By using the whole image, you are leaving nothing for the author/owner of the image. The exact analysis is based on 'fair use' (copyright term, check out the wikipedia page). Noncommercial use is important. And the percentage of the original work you copy is important. Good luck, Todd