The photo above is what the Thames actually looks like - well this afternoon anyhow. And this below is how Canaletto would have painted it:
Ok, maybe he was a bit better than a JP doodle, but you get the idea. Basically its a series of lines showing cuts through waves when actually they are three dimensional moving shapes.
Looking again at the photo above I found myself seeing not lines but patches and blobs, lots of them with subtle differences in tone and colour.
I began to look at it in the same way as the impressionists did - as you can see from the Monet below that I posted some time ago.
Though I think even Monet would agree there's nothing wrong in Canaletto's buildings!