Basic SLR knowledge: Histogram

The histogram is a tool used to determine the photo exposure by displaying the exposure column on the LCD. Through the horizontal and vertical axes of the histogram, We can intuitively see the photo exposure, it brings great convenience to photographers during shooting.

Compared with the pixels of an existing digital camera, the LCD screen used for playback or framing is usually only a dozen or tens of thousands of pixels, and the display size is not large. Therefore, this small LCD screen generally cannot completely show the details of the photos taken. In many cases, even if the impression volume is not accurate, it is difficult to reflect the photo on the LCD. the built-in exposure column of the digital camera provides a good way for photographers to check whether the exposure is accurate. The Coordinate graph in the histogram is the tone curve of a digital photo, which represents the distribution of the tones that constitute the image.

The horizontal axis of the histogram is a gray scale of 256: The left side is 0 (black), the middle side is 127, and the right side is 255 (white ). The vertical axis shows the number of pixels that make up various tones. The closer the line is, the more pixel information is displayed.

The horizontal axis of the histogram ranges from left to right, indicating the number of pixels from the dark to the bright part of the image. The column chart with accurate exposure is distributed from left to right, and has all the details of the brightness and shade. At the same time, there will be no pixel overflow on both sides of the histogram. 1. The vertical axis of the histogram indicates the area occupied by the corresponding part of the image. The higher the peak value, the more pixels the value belongs.

Figure 1 correct exposure

During the shooting process, if the left part of the histogram is very high and the right side is very low, it indicates that the image is too dark. In this case, you should increase the exposure. 2. Insufficient exposure.

Figure 2 insufficient exposure

If the right part of the histogram is very high and the left side is very low, it indicates that the screen is bright, and you should reduce the exposure. 3. The exposure is over.

Figure 3 excessive exposure

When the curve in the histogram is biased toward one side, there may be problems with the exposure. In this case, you should adjust the corresponding exposure value and take a new one. When shooting, remember the principles of white, black, and light makeup. You can also use the exposure method of a digital camera to take photos. These are all ways to get accurate exposure.

The view Histogram can also determine the photo contrast. When all the shadows in the histogram are in the middle, and no vertices are displayed on both sides, the contrast is too low, details are hard to be identified by the naked eye.

Figure 4 Comparison Insufficiency