One of the services I offer alongside my photo / film work is to enhance photos in order to bring out detail otherwise hidden. It's important to note that where a photo is over-exposed, detail in that photo is often lost and for that reason it is generally better to err on the side of caution and under-expose the image or better still, get your exposure 100% right.
Below is an example of a photo taken after sunset using a good quality DSLR camera. The detail in this image appears to be completely missing but in fact, it's still there waiting to be teased out. The image above is that exact same photo processed to bring back the detail that was so sadly lacking in the first. Its quite remarkable really just how much detail still exists in under-exposed images.