Use Photoshop "curves" to color your photos

After opening the image in Photoshop, we can use the shortcut key CTRL m to call up the curve adjustment function.

Before using the curve adjustment function, let's briefly introduce the principle of the curve tool. Photoshop divides an image into three parts: hidden tone, intermediate tone, and highlight. For example, the following image:

We can use the "de-color" command to convert the color image into a gray image, so that we can see the distribution of light and shade: The sky part belongs to the high light, and the trees and lawns belong to the dark tone.

In the curve panel, the two endpoints of the line represent the highlight area and hidden area of the image respectively. The rest of the line is called intermediate, and the two endpoints can be adjusted separately.

The following two animations demonstrate the effect of changing the hidden points and highlights separately. The result is that the highlighted or highlighted parts are highlighted or dimmed.

However, changing the intermediate tone can enable the entire image to be brightened or dimmed (a drag point can be clicked in the online bar), but the contrast between light and shade does not change (different from the increase in the brightness of the TV ), at the same time, the color saturation is increased, which can be used to simulate the effect of natural environment light intensity.

Now we can reduce the darkness and increase the highlight properly.

You can obtain images with strong light and shade pairs (so-called high contrast)

However, this may result in the loss of image details in bright areas (such as clouds in the sky), which is not in line with natural phenomena, in this case, you can change the intermediate adjustment method to create a realistic natural landscape.

In this way, the image looks more natural and there will be no obvious changes.

We adjusted the image as a whole. Now let's take a look at the effect of channel adjustment separately, the images produced by electronic devices are composed of three colors: Red, green, and blue, computer monitors are also so fine, but in other words, the images displayed on the screen are actually composed of three separately colored images (red, green, and blue, the channel refers to the separate red, green, and blue sections, also known as RGB.

If we highlight the red channel separately, it is equivalent to adding the red component in the entire image, and the entire image will be reddish.
If we subtract the dark red channel separately, the result image will be green, the blue and red are reversed colors (also known as complementary colors), red and green, yellow and blue are also reversed colors.
The relationship between the reversed colors is the shift length:
To highlight the yellow color, reduce the dark blue;
To highlight the pink color, reduce the dark green;
To highlight the golden color (the golden color is composed of red and yellow), you need to highlight the red color and the dark blue color at the same time.
Now let's try to change the color of the sky to Golden. Because the sky is in the highlighted area, we need to add the highlighted area of the bright red channel.


At the same time, reduce the highlights of the dark blue channel.

In this way, we get the golden sky effect.

Although this effect is brilliant, the mountains in the distance have also become yellow, and the mountains should belong to the intermediate part. Therefore, we will keep the central part in the original place in the red and blue channels.

In this way, we get the golden sky, while retaining the blue color of the distant mountains.

From the above example, we can see that the use of curve tools can make comprehensive color adjustments. In terms of digital post-processing (not art creation), we should be able to cope with the vast majority of the situations.