Photographs are full of colour, and the eye attempts to take it in all at once. So why not direct the eye to really see something bright and colourful and leave the rest in the background? The photograph still shows the whole scene, but now some part of it, or an object, becomes the focus and a lot more interesting. The original picture with all its colours can still be seen on the facing page but the main focus is that striking bit you get to see on the main page.