The color scale in PS has three sliders from left to right: gray scale, balance and highlight. The rightmost represents the slider, and the adjustment on the right is r g b, all of which are 255, that is, the leftmost represents all zeros after white, that is, all of them are black, and the middle represents balance. You can open a picture and adjust it yourself to see the effect. Mainly used to adjust saturation and bright color. And brightness, etc. Novices can directly adopt automatic color scale. Using color scale to adjust brightness, the loss of contrast and saturation of the image is small. Moreover, the color scale adjustment can accurately set the brightness by inputting numbers.

The curve consists of X/Y axis, X axis represents the color scale before adjustment, from left to middle represents all parts of the image from the darkest to the brightest area, Y axis represents the adjusted color scale, and from bottom to top represents all parts of the image from the darkest to the brightest area. If you want to brighten the dark part of the image, you should adjust the interval in the lower left corner, and adjust the brightness of the bright part of the image by adjusting the interval in the upper right corner.

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. A good picture should have both light and dark details, 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.