What is a histogram? Histogram in photography: how to use?

2024 Author: Sierra Becker | [email protected]. Last modified: 2024-02-26 03:35

Many beginner photographers find it difficult to use the histogram in photography, and some even don't consider it necessary to use it at all. What is a histogram, how does it work in the practice of professionals, and what gives a photograph? What is the best way to correct it - through the camera itself or later when processing the photo through the editor? What should a photographer know about exposure, contrast, chiaroscuro and other essential aspects of photography? More about this in the article.

What is this?

So, a histogram - what is it? Many times, when photographing some kind of panorama or portrait, you transferred the pictures to a computer and wondered why, with such bright full-fledged daylight, they turned out to be too dark or, conversely, overexposed? It is quite difficult to control the brightness of a picture on a small camera monitor “by eye”, but you can adjust the optimal level. A photo histogram is a tool that shows the distribution of light and dark tones in a photo and allows you to achieve their even distribution.

There are sever altypes of histograms on cameras - with a smooth gradient, with columns, with color and black-and-white horizontal lines. The most popular is in the form of a bell. But the principle of operation is the same for everyone - this is a graph that displays the brightness of the image from the darkest tones (left) to the lightest (right).

Before we figure out how to read a histogram in a photo, how to use values from 0 to 255, let's get the opinion of professional photographers and determine for ourselves whether it is needed for a high-quality picture, or you can do without it.

Myths and misconceptions about the histogram

There is a lot of debate about whether or not to use this brightness graph. To understand this, let's debunk a few myths about how and when a camera histogram is used.

• Professional photographers determine chiaroscuro balance “by eye”, without relying on the camera processor.
• Depending on the level of the camera, the displayed data may be incorrect.
• A photo doesn't have to be perfectly metered for exposure, sometimes overexposure or darkening is part of the creative idea.
• Photo histogram generally only applies to black and white shots.
• Professionals often trust the processing of RAW images in Adobe Photoshop, Adobe Lightroom and some other correctors.

In this regard, opinions on the use of charts are divided into pros and cons.

Opinion against

Professionals with a trained eyerarely use this schedule, because it is time consuming and does not always lead to the desired result. For a beginner, it is very difficult to read it right away and understand in which direction to change the metering values, moreover, some erroneous values when photographing will be quite difficult to correct even with correction in the future.

Not all cameras, only professional ones, can give truly correct chiaroscuro values, but they can also be wrong. Anyway, in the future, the picture will have to be corrected in Photoshop and Lightroom editors, so working with the histogram will only take precious time.

Pro opinion

What are the benefits for those who know what a histogram is?

• Even if you are a professional photographer, a second glance at the graph will tell you how rich the picture is in terms of tonal transitions. Moreover, in many digital cameras you can bring it directly to the display and look at it without looking up from the creative process.
• If the shooting is not indoors (for example, in a well-lit studio), but in sunny weather in a park, it will be quite difficult for the photographer to objectively evaluate the image on the screen, because it can shine and show colors more faded than they actually exist. At night, on the contrary, the picture can turn out to be deceptively bright. It is also difficult to perceive the accuracy of black and white on the screen and it is not easy to recognize which areas have been “killed” by contrast. For this, a strict evaluation tool is better suited - a histogram in a photo.
• Sometimes with helpthe histogram can be selected by the camera, it shows the width of the dynamic range, i.e. how many colors the camera can cover when shooting. After all, when buying a camera, it is not always possible to take a picture that will show all colors from the generally accepted range of 0-255.

Summarizing all of the above, understanding what a histogram in photography is, how to use it (practical application) is not always necessary, but not superfluous, since there are cases when this knowledge is indispensable. So let's learn to read it and put it into practice.

How to read a histogram

So, what is a histogram in a camera and why is it needed? Visually, it looks like a graph. On the horizontal axis, from left to right, there are shades from black (dark) to midtones (mid-brightness shades) and white (light). The vertical axis indicates the number of pixels of each hue in the image. As a result, we get several columns of different heights, the higher the column, the more this or that light. Let's put it into practice.

Underexposed Frame

Underexposure means that the frame will be too dark. On the graph, the histogram of the camera is shifted to the left. What to do in this case? This means that there are a lot of dark tones, dark objects, black spots, and almost no light ones. If this is not the intention of the photo, and you are not shooting just a dark subject, go into the exposure settings and add 1-2 points up (value 1, 3; 1, 7).

Overexposed frame

Overexposure indicates the opposite, that the frame turned out to be overexposed (a lot of light, reflections of water, snow in the frame), or you are photographing a white (light) object. Again, if this is not provided for by the plot, go into the exposure and reduce its value to 0.7.

The “correct” frame

Now, knowing what the histogram looks like in the camera with incorrect exposure values, let's look at the correctly exposed frame. Visually, it looks like a boa constrictor that has eaten a hat. This means that shadows and light are present and correctly calibrated, and halftones prevail in the picture. Such a frame looks expressive, contrasting, clear and bright. Plus it will be easier to handle.

Poor frame

The absence of dark and light areas, in other words, contrast, looks like this. The graph or bars are in the center and absent at the edges. This does not mean that the frame was exposed incorrectly, perhaps this is the author's idea and contrasting elements should not be present in the photo. In any case, this ratio can be easily corrected in post-processing.

Peaks on the chart

The histogram has two sharp peaks at the edges. What it is? This option is often obtained when shooting contrasting objects - the ground with dark grasses and clear blue skies, for example. This exposure does not need to be corrected,because it will not show other values.

High key frame

Such pictures are obtained when shooting in bright colors - a white background, a bright sky in sunny weather, clothes in light colors. The histograms in such images are strongly creeping to the right, but this is not a mistake. The photo turns out bright, airy and allows you to concentrate completely on the subject of photography - an object or a person, without being distracted by unnecessary details.

In this case, it is better to leave the exposure at 1, because higher values will lead to overexposure. The brightness of the image can be increased already during processing.

Frame in low key

There is also the opposite situation, when the graph goes completely to the left - for example, a still life is photographed against a black background. Here, too, you should not be afraid of this shift, and adjust all the details, brightness and contrast already in the processing process. By the way, about her.

Editing RAW format

Having figured out what a histogram is in photography, how to use it when processing a photo? Every photographer should know that a picture taken in RAW format retains the settings at which it was taken. Therefore, with the help of Photoshop, the master has the opportunity to correct the mistakes made.

However, there are certain subtleties. An underexposed frame is easier to correct in plus exposure, while an overexposed one is almost impossible to correct. Therefore, lighting situationsbetter not to. To do this, check the exposure of the frame of each photo after work and use the backlight indicator in the camera settings.

How to work with the histogram in Lightroom

Why use a histogram on a computer if you've already adjusted the picture through the camera at the time of shooting? It's simple, this is necessary in order to evaluate how the photo will look on an average computer. After all, on your mac-book it may be perfect, but on a friend's laptop it is completely dark, and on print it is completely different, not what you expect.

With Lightroom's histogram, you can get all the information you need about shadows, contrast, brightness, and more.

So, the histogram in the photo. How to use when processing a photo? In the program, it looks like a rainbow graph. The right side, just like in the camera, is responsible for the light, the left side is responsible for the shadows. The density of a particular color is shown in peaks, the lighter the photo, the higher the pixels on the right will be.

The most important thing to pay attention to when processing is loss in light or shadows. If there are no values on the edge of one of the sides, then the picture has lost some details. For example, dark hair merged into one or the blue sky turned into white.

How to fix this? In the diagram, you will find two triangles on the right and left. If you click on the left one, the loss in the shadows will be highlighted in blue in the photo. If you click on the right one, the loss will turn red.

To fix these losses, Lightroom has sever althe tools that are right below the chart are:

• fill light;
• exposure;
• contrast;
• shadows;
• sharpness;
• changing color and some others.

For example, contrast will help correct a diagram where all the pixels are high in one direction, such a photo has very low contrast. The hump in the middle says the same. But the sharp peaks on both sides of the graph, on the contrary, indicate excessive contrast, which would not hurt to reduce.

How to work with a histogram in Photoshop

Professional photographers are more likely to use Lightroom for exposure and chiaroscuro correction, because this program has a much more complete and convenient toolkit. However, photos can be edited using Photoshop. Here the histogram looks about the same. But with the help of "Photoshop" it is convenient to adjust the resolution and aspect ratio of the image to ensure optimal color reproduction when printing images. It is also very convenient to apply filters, correct defects and change the levels of the photo.

If you are correcting and restoring an old photo, Adobe Photoshop will help you see the correct colors that should be in reality, where highlights or shadows abound.

How to open a histogram in this program? Go to the "Image", "Correction", "Levels" tab. You will see a black-and-white graph in the form of mountains with a range from 0 (pure black) to 255 (white light). To change the exposure, you need to scroll the stripgradient at the bottom, as well as markers under the chart itself.

Learning by doing

The main rule that will help you understand what a histogram means in a camera is to practice more, take pictures with different exposure meters, in different lighting conditions and constantly analyze the resulting pictures.

Take several identical photos - one at +1 exposure, another at +0.3, the third at -0.7. See how their exposures differ. Try switching to a different shooting mode. How has the schedule changed this time?

Check the same pictures with graphic editors, see how they differ from the camera. Only practice can get you better at understanding and the need to use a histogram.

Instead of a conclusion

Of course, not just knowing what a histogram is, but knowing how to use and adjust it correctly will help you take really professional and high-quality pictures. But professionalism is made up of a lot of small knowledge about the intricacies of photography.

Of course, every keen photographer should know the rules for building a successful composition, understand why certain manual settings are needed, such as shutter speed, aperture, focus and autofocus, dynamic range, depth of field calculation and much more. He needs to understand what a proper histogram should look like when shooting in normal, low and high key, and when chiaroscuro loss is considered normal. Where to apply overexposure forunderlining the composition, and where are they a disadvantage of the picture? Where is the amount of black in the frame preventing you from concentrating on the key subject of the photograph?

One thing is for sure, without knowing what a histogram is, it will be quite difficult for you to adjust the settings to get the perfect shot. And whether to use this knowledge constantly or only in some cases is your choice. Good luck with your photo shoots!