Histogram is a “monster under the bed” for many photography enthusiasts. We know it’s there, we don’t see it going away, and yet we don’t want to face it; mostly because we don’t understand it. If we only knew how irrational our fear of a histogram is, we would be able to crawl under the bed, in this case – into our camera settings and play with that monster called Histogram. So, what is a histogram? Basically, histogram is a graph that looks something like the image below. It’s a graph.
Of course, the graph doesn’t mean anything to you but you should at least know that this graph is probably one of the most useful tools available to a photographer. A very simplified definition would say that a histogram evaluates exposure of a photograph after you take it. If you cannot trust your eyes, or you’re shooting in blinding light on a beach or snow and cannot see details of your photo on a LCD screen, a quick look at the histogram can tell you if you lost highlights or shadows in your photo.
In other words, a quick look at the histogram on your LCD screen can tell you whether you underexposed or overexposed your photo.
While the pure graph may mean nothing to you, if you think of it as a way to represent the brightest and darkest areas found on your shooting location, you could imagine it as follows: the darkest values are shown on the left, while the brightest values are shown on the right.
What this particular graph tells us is that this image does not have many very dark (pure black) or very bright (pure white) areas. It means that highlights are preserved quite well and that shadows are well represented, too. Since every photo is unique, each histogram is different. While some photographers say the perfect histogram should resemble a bell shape, many argue that. The shape of your histogram will depend on what type of photography you’re shooting and in what conditions. The example below shows you three photos, taken in very similar conditions, and their histograms.
First Photo: For people who shoot high-key photography, the histogram will always show brighter levels and the first photo is a perfect example. You can see that a lot of highlights in the background were lost and the spike on the right side of the graph tells you that highlights are blown-out. Also, the photo is very flat because shadows are not there (low or no spike at all on the left side of the graph). This photo is underexposed.
Second Photo: The second photo looks better. There are still areas with blown-out highlights (spikes on the right side of the graph), but we have more shadows; however, we don’t have any true or pure blacks in this photo either.
Third Photo: The third photos has an all-over even exposure, no blown-out highlights (notice the absence of the spike on the far right), we have nice shadows (the left side of the graph), and the midtones are well present (quite balanced spikes throughout the graph).
It’s that easy! Yes, there is more to histograms, but we will stop here and continue some other time. I hope you got a basic understanding of histograms and that you will be able to read it next time you see it on your LCD screen.
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