The digital photography histogram is a handy tool to ensure your pictures are light and color balanced, and is well worth the effort of learning how to interpret and use it.
Some cameras show the digital photography histogram in real time, allowing you to make adjustments as you go along.
What is a digital photography histogram? A histogram will show if there is enough detail in the shadow, midtone and highlight areas of your image, and importantly, whether or not your picture is overexposed.
The digital photography histogram indicates how the 256 levels of brightness are distributed in an image. Compare it to a horizontal line with 256 positions which represent all levels of brightness from pure black on the left, to pure white on the right.
It consists of a little graph which indicates hills, valleys and spikes of data according to the number of data pixels present for a given level of brightness. If your picture generally has low contrast, the pixels will cluster in the midtone (grey) area of a digital photography histogram.
An image with high contrast will have high stacks of pixels on the opposite ends of the graph, with fewer in the midtone area.
An overexposed image will show a lot of pixel data stacked on the far right side of the graph (lots of white). If you have most data on the left, and a big space to the right of your data, your picture is likely underexposed.
If you are new to the concept of the digital photography histogram, it takes a bit of time to interpret, but you will soon begin to see how the graph relates to your pictures.
For example, the digital photography histogram of an outside picture with a lot of dark sky and little color variation in the rest of the picture, will show a strong spike on the left (dark sky) and a low horizontal bar all the way to the right, indicating little variation in light intensity.
In overexposure you lose data that you can't get back - even in Photoshop! Many photographers would argue that it is better to underexpose slightly. You can then correct a good deal of underexposure in an imaging program like Photoshop. It lets you distribute the lightness values of pixels more evenly across the spectrum from black to white.
Do you need the digital photography histogram? Many photographers never look at a histogram, but just view the images to check for exposure.
You will find that you are able to analyze your pictures in greater detail, and even to correct them afterwards in an imaging program like Photoshop, once you have mastered the digital photography histogram!
