Updated Feb, 25th 2013
I took this picture today at Arpoador, a very touristic place in Rio de Janeiro, where you can see one of the most famous sunsets in the world. This is the original:
I used iPhone 5. I've never used Lightroom before. I tried to make some subtle changes with highlights, shadows white balnce and saturation. Here's the result:
Here's another shot of the same place.
The funny thing is that I had no intention to transform it into black and white. However, the main feature of this picture is the vanishing point, and I thought the colors were too distracting. Not 100% sure it was the best decision but it felt right. In black and white mode, I increased the clarity of the green, so I could get more contrast between the plants and the poles. Put some vignette too, and made general adjustments in contrast, details and highlights.