In my opinion, photography is an art-form and not just a method of recording, as some purists would believe. Enhanced images can be much more appealling than the basic photograph that comes straight from the camera. My motives are to recreate the emotions and experience I felt at the time of taking the photograph. Digital processing is a very personal thing - what might look good to one person might appear over processed to another. For me processing photographs is not digital art; replacing skies or adding people is not my thing. The following recent photograph is used as an illustration to show the sort of procesing that I use to bring night shots to life.

O r i g i n a l

These are three exposures of an old church which lies just outside Shrewsbury castle gates. The photograph was taken in the evening from inside a doorway in the library grounds opposite. There was still some light in the sky and there were a mixture of reflections on the door from the sky itself and several street lamps in the library grounds.
The door adds foreground interest and the archway leads the viewer's eye to the gardens beyond and finally to the stonework of the old church. Whilst taking the shot I also noticed a sign outside the door arch which said 'Welcome' on it. As a final touch I tried to position the camera to include it in the frame.
Due to the small dynamic range of the camera compared to the human eye, none of these shots give a version anywhere near what I remembered seeing. Only the longer exposure copes with the dark interior immediately in front of the camera and only the short exposure deals with the bright lights of the church. The medium exposure has problems with both.
The Raw files were first saved onto an external hard disk and then imported into Digital Photo Professional. I sometimes use Camera Raw depending on what needs doing to the photos. In this case, the white balance was adjusted to decrease the red tones in the lights and because there was a lot of delicate detail around the church I did not adjust the noise at this early stage to try and preserve it. The photos were then imported into Photoshop as a series of 'tiff' files.

P r o c e s s e d

In Photoshop the photos were stacked into 3 layers by dragging them on top of each other (shortest exposure on top). To achieve the correct exposure for the church I used the opacity slider to blend the longest and medium exposures. I then created a layer mask for the shortest exposure on top and brushed in the correct church exposure with a soft black brush, revealing it from underneath. The layers were then flattened.
'Levels' were adjusted to increase brightness, contrast and tonal range. Further work on contrast included a method called 'Local Contrast Enhancement'. Here is a link to an article that describes how it is done at a Luminous Landscape:
Understanding Local Contrast Enhancement
Viewed at 100% I then looked for dust marks caused by a dirty sensor and used the 'spot healing' tool to get rid of them.
Noise was cleaned up in the sky by selecting it with the magic wand and using the 'noise reduction' filter.
I then sharpened detail by switching to 'Lab' mode and sharpening the B&W channel using the 'unsharp mask' tool.
Switching back to RGB I dodged and burned a little and the colour was given an adjustment using 'curves', the 'droppers' being used to select black and white points on the image. Finally, I cropped a little closer to add impact.
And there we have it, the finished image as I remembered it!