Reading a histogram
The histogram is one of those tools that, once you learn how to use it, can really revolutionize your photography. To me, it’s so important that on my camera instead of showing a preview of the photo when I shoot, I have the camera show the photo’s histogram instead. It’s quite simple, yet commonly misunderstood so I decided to do a quick little guide explaining it.
What is the histogram.
The dictionary says:
A bar graph of a frequency distribution in which the widths of the bars are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies.
But that doesn’t really make all that much sense. Ultimately, the histogram is a sort-of bar graph that represents the brightness of each pixel in your photograph.
How to look at the histogram.
Think of the histogram as a really compact bar graph, because that’s exactly what it is. There are 255 bars that represent the 255 levels of brightness for each pixel. All the way on the left are your darkest pixels, and all the way on the right are your brightest pixels. In the histogram example above, you can see that most of the pixels in the image fall into the midtones range.
What makes a good histogram?
Like anything in photography, or art for that matter, it’s subjective. A good histogram is one that represnts the exposure you were going for when you took the photograph.
That being said, typically you would want a histogram to show that you have a good amount in the midrange, without anything being pushed of either edge.
You can see that in this histogram, that the image has a lot of lighter pixels, but none of them are all the way to the right showing that the whites are blown out and have lost all detail. That is the histogram for this photograph.
On the other hand, If I turn up the exposure in Lightroom a bit, you can see that the whites are completely blown out, and if I reduce the exposure, I will lose all detail in the blacks (there aren’t many in this photograph)
None of the histograms are necessarily right or wrong , but it’s important to be able to see the difference, so you can analyze them on the fly in your camera when you are out on a shoot.
Overall, the histogram can be an incredibly useful tool when you are taking photographs, and they have a tendancy to be incredibly useful when you are shooting under dramatic conditions where you are trying to be careful not to blow out your whites or underexpose and lose detail in your shadows.
I would love to hear what you have to say, and if you feel I missed something please let me know!