Should I cite or credit images I found online for a conference presentation? I am going to do a conference presentation on so-called Smart Cities

As you can imagine, the concept of a Smart City is best conveyed using pictures (it is worth a thousand words).

I found a picture which I think can capture this concept



There are others like it,



Since I didn't create them, therefore technically I think I should credit these images, but it is a lot of extraneously and unnecessary information for the audience. 

I also see that many people do not credit images when they are presenting, and I would wager a guess that most of those images are not generated by themselves. 

Should I attempt to credit or cite this image?
(Not an IP expert, just a researcher who has struggled with the same question).

Even citing them may not be enough. Fair use doesn't extend as far as most people think it does: for the exception to apply, you have to be using the materials in a "transformative" way, not in the same way as the original work. Further, the conference may be considered a commercial activity even if you personally are not benefitting financially. Note also that the copyright holder may not be the author, but the journal in which the figure was published.

Thus, I suspect the "legally correct" answer to your question is that you should ask the copyright holder for permission to reproduce the image, and also ask them if they want to be attributed.

As you say, most people just use images willy-nilly, hoping that the copyright owner will not complain. In a conference talk in which the slides are not publicly available, that seems like a safe bet.

Note that for more mundane pictures (e.g., a picture of a dog for a computer vision project), there are some sites that specifically waive copyright and do not request attribution. This may be a good way to reduce the number of pictures that you need to cite and/or try to get copyright permission for.