How to understand the histogram of a digital camera?

When the LCD monitor of a digital camera plays back an image, a graph showing image brightness or both brightness and color is called a histogram. Modern digital cameras almost have the function of histogram (it has the same principle as the histogram of computer software, and the bee-like shape is similar. The difference is that it can only view pictures but not edit pictures). The histogram represents the number of pixels in each brightness level of the image, showing the distribution of pixels in the image. The purpose of viewing the histogram is mainly to see whether the image exposure is correct and the color status, to provide a reference for continuous shooting, so as to correct the exposure combination and color temperature setting in time.

The horizontal axis of the histogram is from left to right, it can be said to be a gray scale spectrum, representing the gradual change from 0 black to I black gray, II dark gray, III dark gray, IV light dark gray, and V level. Medium gray, grade VI deep and light gray, grade VII light gray, grade VIII extremely light gray, grade IX gray, and grade X white, a total of 11 grades. In terms of reproducing the details and texture of the subject, the 0 and V levels have no reproducibility, and the I and IX levels are minimal. V-class mid-gray (18% reflectance) is the standard exposure, with the strongest reproducibility.

The horizontal axis is from left to right, indicating the brightness range of the image from dark to bright. The vertical axis, from top to bottom, represents the number of pixels that constitute the image at the corresponding gray level (the higher and wider the honeycomb pattern, the more pixels, and vice versa). In the histogram, where there is a bee pattern, there are pixels; otherwise, there are no pixels. The bee image to the left means that the dark part of the image has pixels and details; the bee image to the right means that there are pixels and details in the bright part of the image; the bee image on the left means that there are no pixels and details in the dark part of the image; the bee image on the right means the image The bright part has no pixels and no details; the bee pattern is too far to the left (with overflow) or too far to the right (with overflow), indicating that the exposure has exceeded the dynamic range of the photoreceptor (equal to exceeding the latitude of the film).

If the histogram is in color, the three curves of red, green, and blue on the bee diagram represent the hue of the image and the distribution of the three primary colors red, green, and blue that make up the hue. You can understand the color saturation, color gradient and white balance deviation of the image . Compared with the three color bee patterns, the wider and higher the bee pattern of a certain color, the more pixels that contain a certain color, and vice versa. Overflow on the left indicates dark colors and no details; overflow on the right indicates bright colors and no details. The three color lines are close and close to balance, indicating that the color balance is good.

About bee graph overflow. The color range that can be displayed or printed by the color system is called "color gamut", and the color gamut beyond is called color overflow. There is overflow at the left end (commonly known as on the wall), which means that the exposure is under-exposure, and exposure compensation needs to be increased. It is better to add to the bee image without overflow or blank. There is overflow at the left and right ends, and there is no bee pattern in the middle or the bee pattern is very low, indicating that the contrast is too high.

Digital photography should be "exposed to the right," and the histogram just doesn't overflow right.