How to understand the histogram of exposure brightness

You can see the photos immediately after you press the photo button of the digital camera. Not only can you see the photos, but you can also see all the data when you take pictures; You can not only see the data, but also see the brightness statistics of this photo. This statistical table is exactly the brightness histogram that we judge the exposure by combining photos.

Histogram, also known as histogram, is very vivid. Have you ever used a spreadsheet? Just like Microsoft's Excel spreadsheet, Apple's numbers and so on. The essence of histogram is some two-dimensional statistics. These numbers are connected to form curves, which are cut into cakes and called "pie charts". If represented by different columns, it is called "histogram" or "histogram". You can see the trend of the market and individual stocks on the financial channel every day. I don't buy stocks, and I don't understand them, but I know those high and low lines are statistics by time. So, what is histogram statistics in digital photography? As far as exposure is concerned, the histogram counts the number of pixels according to the different brightness from black to white. That's too abstract. It's clearer with a schematic diagram. First of all, we divide black into seven levels of light and shade (remember "hue"? ), including black and white. The horizontal axis of the histogram represents the brightness level, with black on the left, bright color on the right and white on the right. Suppose we have a 22-pixel photo, the statistical result is, for example, the histogram above. Then we can see from this histogram that three pixels in the photo are black, two pixels are white and five pixels are medium gray. ...

Brightness histogram in digital camera

Now, let's enlarge the histogram of the previous page a little: expand the color scale from black to white to 256, and increase the total number of pixels to10 million or 20 million pixels. In this way, we have restored the histogram in the digital camera. It looks like this. It looks like a mountain, doesn't it? Yes! The high place is called "mountain peak" and the grounded place is called "foot of mountain". Beginners can easily mistake the higher the mountain, the brighter it is, which is also an important reason why they can't understand the histogram and feel confused. Remember, the light and shadow tone of the photo is on the ground of the histogram, with the left side dark and the right side bright, and the left side black and the right side white. The height of the histogram only represents the number of pixels at the tone level. The height of the peak represents that there are many pixels in the shadow area where the peak is located. In other words, the higher the mountain peak, it means that the total area of the tone area in the picture is relatively larger.

Let's take a look at the histogram above, which is the tone statistics of a digital photo. As can be seen from the histogram, most of the pixels in the picture are stacked in middle tones, with more light and less dark. In digital photography, this histogram that counts the number of pixels according to the tone level is called "brightness histogram". Brightness histogram is an important reference tool for us to judge exposure.

Where is the histogram displayed in the digital camera?

Many card machines can see the histogram from the back screen before shooting (they usually only have the back screen). Most digital cameras can't see the histogram of photos until they have finished shooting.

First, play back the photos to the back screen. Then, Canon camera presses the "information" or "Disp" button until the histogram appears in the upper right corner of the screen; Nikon camera press the up and down keys or the left and right keys (if the left and right keys are for changing photos, press the up and down keys) until the following figure appears. The photo is in the upper left corner of the screen, the histogram is in the upper right corner, and the shooting data is below. Different manufacturers provide different histogram segmentation areas in cameras. For example, Nikon divides the histogram into four regions, and Canon divides the histogram into five regions. All right! Now, do you remember the four or five tone areas mentioned earlier?

No matter how many regions are divided, it is only for the convenience of judgment, and the essence of histogram has not changed. Even if you don't have a histogram of the partition, you can easily understand it. Remember: the left side is dark and the right side is bright. The higher it is, the more space it takes up. However, in the following discussion, for the convenience of analysis, the histogram will be divided into 4 or 5 regions. Therefore, we still need to be clear about the consistency of tone. The above pictures and texts are taken from "Digital Photography Exposure from Entry to Mastery" by People's Posts and Telecommunications Publishing House.