This enhancement is created by using Adobe Photoshop.
You start by opening up you original image into Photoshop. Below is the image i started with.
Images with buildings or lots of sky work well.
I started by duplicating the layer. I then followed the steps of Image > Adjustment > shadows & highlight. Roughly you can changed the shadow to 30% and highlight - 50% but this is vary depending on your photo so its all a matter of your own judgment.
Under the shadow and highlight sliders is an 'Option box', click on it and more sliders will appear.
You can changed the 'Mid tone contrast' to around +50 this gives the colours a stronger effect within the image. Also change the 'colour correction' to roughly +20 this makes the colours look realistic.
You can continue to play around with the others but again it is all a matter of opinion. Then click OK.
Again duplicate your original image and drag the layer to the top so its above the rest. Select Filter > Other > High pass. Change the radius to about 10 pixels. After select Image > Adjustments > Desaturated and change the blending mode to overlay. By doing this it allows the contrast in colours so be more prompt.
Finally select Layer > New adjustment layer > Colour balance. Then change the 'Highlights'. You can adjust this to your preference but i started by adding more yellow and red.
I then changed the 'Shadows' by adding more blue, green and Cyan.
But again play around with the sliders till you find a colour your happy with.
This is my final outcome. I enjoyed creating this digital effect as it allows me to use my own opinion to get the best possible effect. Although it can give an artificial effect I still think it looks great.