Histogram and LCD – The matter of Trust

The article is about Histograms and how to read them. The histogram is one of the most useful tools in the world of photography and often the most misunderstood. A histogram is a tool which guides us to evaluate the exposure of a picture. Understanding Histogram makes a big difference between an amateur photographer and an advanced one. So once you understand and start using this, you’ll be one step closer to being an advanced photographer.



Can’t just we use the LCD like always?

Yes, you can. After all , Histograms don’t replace your eyes and experience. But in some situations, you cannot rely upon LCD. The issue with LCDs is, they can’t be trusted. There are two reasons. First, you can misread the exposure of an image in certain situations like in bright sunlight. Secondly, changing the brightness of your LCD screen can cause you to misread the exposure.

One important thing is, you cannot be sure if there are details missing in a picture due to overexposure or underexposure just by looking at the LCD. So the question is which one to trust, LCD or Histogram? I’ll say the combination of both. Use Histogram as a guide, and eyes for the experience of picture.

Histogram and How to Read it

There are many complex definitions for it. But I’ll make it simple for you. It is a graph showing the brightness distribution. In other words, a graph which counts the number of pixels at each level of brightness. Didn’t understand this, don’t worry, who cares about the definition :). All we care about is the usage. A typical histogram is shown below.


The far left is the dark or pure black, called Shadows, and far right is bright, or pure white called Highlights. And area in middle is called Midtones.
If an image is underexposed, the pixels in the graph will be concentrated towards the left.
If an image is overexposed, the pixels in the graph will be concentrated towards the right.
And a correctly exposed image is the one in which the graph is spread all over, not concentrated towards any end.
Here are few examples.
Histogram for an underexposed image will look like the following image


You’ll see the graph moved towards the left end, that means there are more dark pixels and fewer bright pixels. In other words, it is underexposed.
An example of overexposed image
Opposite to the previous image, the graph is leaning towards the right end, that means there are more bright pixels, or it is overexposed.
So how does the balanced or nicely exposed image looks like



I annotated the picture just to make clear which area represents which part of the histogram.

Keypoints while reading histograms

Well, if you are still not confident much about reading the histogram, I’ll make it little more simpler. Here are some keypoints to keep in mind while reviewing a histogram.

  1. If a histogram is leaning towards the left or if there is a big gap between the end of the histogram and far right, the picture is underexposed.
  2. If a histogram is leaning towards right or there is a big gap between the far left end and the start of the histogram, that means the picture is overexposed.
  3. If you find the graph being clipped off from either end, that means there are some details missing. Either due to overexposure or underexposure, depending upon the area being clipped off.

And if you find incorrect exposure, there are ways to correct it. One of them is exposure compensation. I’ll be shortly coming up with an article on that.
If you keep these three keypoints in mind, these will work, most of the times. Remember, the histogram is just a guide, not a master. There is no hard & fast rule for beautiful pictures. This is just a tool which can help us to evaluate the exposure in conditions where we cannot rely upon LCD screens.

Should we stick to it?

No, not at all. Photography is about breaking the rules (after knowing them). So consider this as a helper. But you don’t have to stick with it. Because sometimes, you want to get some pictures whose histogram can’t be perfect. I’ll show you an example


This picture doesn’t have a perfect histogram, but still, it is beautiful. You know why.


Understanding histogram will add one more skill to get good pictures. There is no perfect graph in histograms which can get you the best picture in the world. Histograms are just a guide which can help you better evaluate the picture. And you become one step closer to being a Pro. I’ll be shortly coming up with a new article on more advanced details, Color Histograms.

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