Brightness and Contrast for Dark Images
Lighting conditions for any photo session are seldom perfect, making brightness and contrast problems one of the most frequently seen issues in consumer photography. Brightness is essentially the total amount of light (or white) in a pixel, while contrast is the difference in brightness between various pixels. Since brightness and contrast are so closely related, they’re usually adjusted together (usually brightness first, and then contrast).
The image below shows problems with brightness, where the overall darkness of the image makes it difficult to see details.
Of course, how much to brighten an image is an issue of personal preference, but tools such as a Histogram can help (more on this later). It’s usually best to brighten an image in increments, such as by six or 12 points. One the brightness is close to what you have in mind, you can then fine tune by increasing or decreasing the brightness one point at a time, until the brightness looks correct.
Once brightness was applied to this photo, it looked somewhat faded, which is an issue easily corrected with a contrast adjustment. I increased the contrast by 36 points, which brought out details and even made the street signs more legible.