Hue/saturation

When we were not familiar with the color adjustment, we were in touch with this color adjustment method. It is mainly used to change the color of an image. It turns red into blue, and Green into purple. Now let's take a look at this adjustment method. We use the floral image below.

[Image> adjustment> hue/saturation] open the setting box and we know that the slider that pulls the hue can change the hue, note that there are two color chromatography below (the chromatographic knowledge is in course #01), where the chromatography above is fixed, and the chromatography below will change with the moving of the color slide bar. The two chromatographic states are actually the result of the color phase change.
The left figure is shown below. Observe the color chromatography changes in the two boxes. Before the change, the red color corresponds to the red color and the green color corresponds to the green color. After the change, the red color corresponds to the green color, and the green color corresponds to the blue color. This tells us the effect of changing the corresponding color area in the image. As shown in the right figure below, the red flowers change to green and the green leaves change to blue.

 

[Color = # ff0000]0703[/Color]
Saturation is used to control the brightness of the image, similar to the color adjustment in our TV set. The chromatography at the bottom of the change will also change. When it is adjusted to the lowest level, the image becomes a grayscale image. It does not apply to changing the color of a gray image.

Brightness is the brightness, similar to the brightness adjustment of the TV. If you set the brightness to a minimum, black is displayed, and White is displayed when you set the brightness to a maximum. It has no effect on changing the color or saturation of the black and white colors. You can perform an experiment on your own.
[Color = # ff0000]0704[/Color]
There is a "color" option in the lower-right corner of the setting box, which is used to change the screen to the same color. Many digital wedding photography often use this effect. This is just as simple as clicking the "color" option and then pulling the color to change the color. The left figure is shown below. "Coloring" is an operation that replaces color with monochrome, and retains the original pixel brightness. Convert the red, yellow, and purple colors in the original image into a single color with different colors. Note that the color at the bottom of the row changes to Brown, which means that the brown color replaces the full color, so the image should now appear Brown as a whole. More pull slide bar can choose different monochrome. The remaining three figures are shown below. You can also adjust the saturation and brightness at the same time.


 

 

Now there is a problem. We need to change the red flowers in the screen to green ...... It's easy, not just to change the color as before. Don't worry. The problem is not finished yet. Turn the red flowers in the screen into green ...... However, the original green leaves cannot change to blue.
What should we do? Readers may think that they can use the magic wand to select the red area on the screen and then change the color. Yes, if you really think of this method, it proves that your thinking is very active and you know how to use it comprehensively. However, this is not necessary. In the color saturation option, you can specify to change the color of a specific color area separately.
[Color = # ff0000]0705[/Color]
As shown in the following figure, select red in the edit option above, and a regional indicator appears in the lower section of the chromatographic chart. Now we can change the color to + 128, as shown in the left figure below. Only the chromatography in that range has changed. The bottom right is the changed image.
To change the value, you can either pull the slider or enter a number. You can also use the scroll wheel in the number area or press the up or down arrow or press CTRL to drag the slider, at last, you can drag the text on both sides. We have studied these methods in course #03. Here we will review them. They apply to all similar places where values appear. Drag is suitable for changing values in a wide range. The scroll wheel and the up and down arrow buttons are suitable for small-scale changes.

 

Let's zoom in on the indicator that appears in the upper left graph. As shown in the following figure, the color gamut is divided into two parts: the central color gamut and the radiation color gamut. The central color gamut refers to the chromatographic range to be changed. The value of the upper left is 345 ° to 15 °. The radiation color gamut refers to the effect of the change of the central color gamut on the adjacent color gamut. The values in the upper left are 315 ° to 345 °, 15 ° to 45 ° respectively.
Move the four borders with the mouse to change the range of the central or radiant color gamut. Drag the left and right of the central color gamut to move it to another color gamut.
Use a straw tool above the chromatographic bar

Click in the image to move the central color gamut to the selected color area. Use the add to sampling tool

You can extend the color gamut to the selected color area. Subtract tool from sampling

In contrast to the addition of sampling tools. Add to sampling tool

During use, you can drag the image to observe the effect of the change in the center area. It is more intuitive than clicking selected. The other two tools are not suitable for this operation. Because the effect of addition and subtraction changes sharply.
In fact, the other items listed in the edit option change the location of the central color gamut, which is the same as the direct drag with the mouse. You can use this method to change the green color.
It should be noted that the color effect of the radiation color gamut starts from the border of the central color gamut and gradually decreases to both sides. If some colors do not change significantly, the range of the center or radiant color gamut can be expanded.

Why is the unit here an angle? We have already mentioned the principle in the course #01 and #03. The color chromatography is originally a ring, which can be changed to a long bar for convenience of operation. Why do we need to explain basic knowledge that seems unrelated to Photoshop operations at the beginning of the tutorial? If we don't learn that knowledge first, it will be inexplicable here. If we only explain the principle of the color scheme here, it will cause a large amount of knowledge, which is not conducive to absorption. These basic knowledge will be useful when we learn more software in the future. Next, we will list the pictures in the previous course. For everyone to review.

 

Next we will do a small exercise to change the color. The title is "new varieties of Blue Watermelon". First, let's take an introduction to cultivate your emotions.
This is a test project of the DNA laboratory of Fuzhou Agriculture and Forestry University. It only covers 1 mu of land, because my classmates work as teachers at the Agricultural University, and I am working as a part-time teacher there during this time, so today I got one. Blue watermelon heads are big, generally more than 15 kg, cut the consequences of the meat is dark blue, looks strange. Others did not dare to eat it. I ate it on the seventh day and found that the taste is similar to that of the red flesh. People in the lab said that this breed could not continue to grow the next generation, and their topic was over. In other words, this watermelon was unprecedented! Watermelon has been red for thousands of years, but today it turns blue. Humans are brave.
Well, even we have a bit of confidence. Now let's open the image, as shown in the left figure below. Use the color/saturation tool ctrl u, select red in the editing options, and change the color to + 180. The watermelon flesh in the image changes to blue. See the following picture on the right.

 

Seems to have finished? If it is so simple, it won't be a master's work.
Note that when the red flesh changes to blue, the red edge of the left-side stove of the image and the red hose in the upper right corner of the metal water bottle also change color.
More importantly, there is a flaw. Pay attention to the big watermelon on the right side of the large white bowl of the source image. There is a small piece of watermelon under it and the light red of the leftover melon skin is reflected, after the change, the reflection looks very stiff. This is because the light red is reflected on the green melon skin, and the red is not very heavy, so it is actually blended with the green. However, the central color gamut and the extended color gamut on the chromatographic Bar do not involve the green color, resulting in the situation that "only red changes, no green changes. Therefore, the area looks very stiff and forms a plate (also known as color spots), without the original smooth and natural color transition.
Why does the flesh and surrounding areas not produce color spots? Because the red color of the flesh is very heavy, it is strong to the surrounding color.
How can we solve the color spots? As mentioned above, if some color changes are less effective, the range of the center or radiant color gamut can be expanded. Does it change the central area or the radiation area? This is an analysis. If the center area is expanded to green, it will inevitably lead to all the green changes in the image, including the water bottle, tea pot, and cup, which will also lead to the color change of the melon skin, you can try it on your own. Therefore, this method does not work.
Therefore, we drag the radiation range on the right of the central area to the green area, from the existing 45 ° to around 60 °, and we can see that the original color spots appear smooth. As shown in the following figure. At the same time, the melon skin on the top of the white wrist also changed color, but it did not have a significant impact, so ignore it. Although the effects of the changes are very subtle, the pursuit of perfection is not to let go of a trace of detail is the master's style.

 

Well, this subtle flaw was removed by us. How can we solve the color of the stove and hose? To solve this problem, we can't just change the color. We need to take advantage of one of the features of Photoshop we mentioned earlier: Once a constituency is created, all color adjustments can only be effective for the constituency. Therefore, the answer is to create a selection area excluding the stove and hose, and then use the color/saturation tool ctrl u. The left figure is shown below.
Careful readers may find it strange: Why is the knife on the desk excluded? Isn't there a red mirror on the knife surface? The reason will be discussed later. Now we have changed the color effect according to the settings mentioned above. Because the original Blue is too bright, this time we will change the brightness to-20, so that the dark blue is more realistic. See the following picture on the right. During the adjustment process, the border of the selected area will always exist. If you find it difficult to observe, press ctrl h to hide the selected area. However, if the selected area is changed (new or modified), the hidden area will automatically become invalid.

 

Well, now I want to explain why we want to eliminate the cause of the knife. It is to give careful people a chance to discover flaws. Most people see this picture and think that there are actually Blue watermelons in the world, which falls into our first calculation. People with a certain degree of Image Processing Foundation will try to find traces of modifications after a short period of surprise. When they find this subtle flaw and are excited, they do not know that they have fallen into our second calculation.
The following are some of the speeches made on the blue watermelon in the forum.
I don't know if there are any seeds. I planted them in Jiangxi. (
/Bbs
)
A person like me can see it at a glance. Isn't it just applying paint on the watermelon? Hum. To be painted must also be painted red. (Mainland China)
After a few years of eating this transgenic product, we will have N ears ...... (Mainland China)
After eating, I always shake and say "real ice ~ Cool ~ "Or immediately frozen... (Hong Kong)
Will it be poisoned ~?? (Hong Kong)
The Blue Watermelon really does not exist... and it does not exist to breed the next generation. Only those who really have access to gardening will know these things, which our teacher told us. (Taiwan)
It must have been sprayed with iron ~~~ (Taiwan)
Finally, I will tell you that our final work is still flawed. The flaw lies on the left of the glass, at the bottom of the white pot containing honey. Have you noticed that blue? To remove it, you must exclude it when creating a constituency. However, you do not have to redo it completely. You can return to the step after the constituency is created, subtract the region, and then adjust it.
You can also directly use the history erasure function to achieve the purpose without returning a result. The specific method will be described later.
Well, refer to our previous ideas to adjust the color of the lower left to the lower right. The preparation steps are at the end of this lesson.