How to look at the histogram on the camera and understand its meaning?

The horizontal axis of the histogram represents the number of pixels in the photo from black (dark part) to white (light part) from left to right. From the usual point of view, a better picture should have both light and dark details, which are distributed from left to right on the histogram, and there will be no pixel overflow on both sides of the histogram. The vertical axis of the histogram represents the area occupied by the corresponding part of the picture. The higher the peak value, the more pixels there are in the bright and dark values.

In the process of shooting, if the left part of the histogram is very high and the right part is very low, it means that the picture is dark, so we should increase the exposure (positive compensation), otherwise we should compensate negatively.

By looking at the histogram, we can also judge the contrast of the photos. When all the colors in the histogram are gathered in the middle and there is no vertical display on both sides, the contrast of this photo is likely to be too low, and the details will be difficult to be recognized by the naked eye.

If the whole histogram runs through the horizontal axis, there is no peak, and both ends of light and dark overflow. The contrast of this photo is likely to be too high, which will cause irreversible loss of light and dark details at both ends of the picture.

However, from the perspective of photography creation, it is sometimes necessary to use special techniques to express the subject. For example, common high-profile and low-key photography is to hide some unnecessary details or backgrounds through overexposure or underexposure. Taking such a work, the histogram must be obviously biased to one side, but it can't be said that such a photo is not exposed correctly.

Therefore, whether the exposure is correct depends not on whether the histogram is evenly distributed, but on whether the photos taken are exposed according to our intention. This is the standard to test whether it is correct.