The front of the photo

On the screen of most digital cameras, the histogram can be displayed at the same time when previewing photos. In fact, even an old bird who has been playing photography for many years, many people still don't understand the function of histogram. Most photographers' camera screens are set to the whole screen to display photos. In fact, histogram plays a vital role in professional photography creation. Histogram can not only indicate whether there is overexposure or underexposure, but also indicate the distribution range of different light and shade. It is more accurate to look at the histogram when previewing photos than simply looking at photos.

This paper briefly introduces the significance of histogram expression.

Simply put, the histogram is a two-dimensional coordinate axis, representing the darkest to brightest colors that can be accommodated in the camera. The length of the horizontal axis represents the total range from left to right and from darkest to brightest on the camera. The leftmost represents all black, and the rightmost represents all white. The length of the vertical axis represents the number of pixels. As we all know, a photo is composed of tens of millions of pixels, depending on the camera model and settings. The vertical axis is the number of pixels collected at this brightness. The higher the number of a certain part, the more pixels of this brightness in the photo. To put it bluntly, this is the continuous histogram, or waveform chart, which is generated after we collect enough data from statistical data. Essentially, it is a statistical picture of pixel brightness in a photo.

Understand the meaning of histogram. We will start to think about what the ideal histogram looks like. Judging from pure theory, most people will think of it. Theoretically, the ideal histogram should be a continuous and gentle mountain shape, as shown in the following figure.

This point, many photographers or textbooks will immediately correct, saying, no, this is not the histogram of the ideal state. I said, yes, if all other considerations are put aside, this is an ideal histogram form in theory, if there are such photos. Now that we know the meaning of histogram, we can imagine what it would be like to have such a photo. This should be a picture with pixel gray levels ranging from the darkest 0 to the brightest 255. And this photo has the most pixels in the middle tone. There is a high contrast from the darkest to the brightest, and there is a bright middle tone that occupies most of the picture. This is a beautiful exposed photo. Theoretically, of course.

In actual shooting, no matter because of the limitation of shooting environment or the need of creative intention, we will never take such a photo.

If you shoot the clear and beautiful sky, the vast sea and the horizon connecting the sea and the sky. The mountain shape will definitely shift to the right, because bright colors are the main colors.

If you are shooting dark lights, dark alleys, or even brightly colored flowers, there is nothing wrong with moving the histogram to the left.

Even in many cases, the histogram of the photos we take is not a mountain shape with high middle and low sides (such as the title map in this paper), but as long as your objective environment and subjective creative intention are to express this contrast between light and dark, the shape of the histogram is not right or wrong.

Of course, if the number of pixels on the left or right side of the histogram rises sharply, and then a high cliff is formed at the edge, it means that your photo has a lot of underexposure (there is a large area of underexposure in the night sky above) or overexposure. So photography is an art, like painting, like music. We can't see the characters in The Naked Woman Descending the Stairs, which doesn't affect that it is a great work. It depends on what the author wants to express in his work.

Histograms can't tell you whether the exposure is right or wrong. Photography is art, not mathematics. Histogram will only tell you the pixel information in the photo, and the author will judge whether this information is exactly what you want to express.