This article learns the RGB color mode in ps
We use a magnifying glass to look closely at the screen of a computer monitor or TV, and we will see a large number of small dots divided into three colors: red, green, and blue. As shown in the left image below, the lower right image is a partial enlargement of the left image. All the colors on the screen, that is, all the image content we see, are made of them.
Press〖F8〗or from the menu【Window_Info】to bring up the information palette. As shown on the right below. Then try to move the mouse in the image, you will see the values in it are constantly changing. Note that when you move to the blue area, you will see that the value of B is higher; when you move to the red area, the value of R is higher.
All the colors on the computer screen are made up of the three colors of red, green and blue mixed in different proportions. A set of red, green and blue is the smallest display unit. Any color on the screen can be recorded and expressed by a set of RGB values. Well, the leftmost image seen below is actually made up of three parts on the right.
In the computer, the so-called "how much" of RGB refers to the brightness, and is represented by an integer. Under normal circumstances, RGB has 256 levels of brightness, which are represented by numbers from 0, 1, 2... until 255. Note that although the highest number is 255, 0 is also one of the values, so there are 256 levels.
According to the calculation, about 16.78 million colors can be combined with 256 levels of RGB colors, that is, 256×256×256=16777216. It is also commonly referred to as 16 million colors or tens of thousands of colors. Also known as 24-bit color (2 to the 24th power).
There is also a weirder name for this 24-bit color, which is 8-bit channel color . Why is it called this way?
The so-called channel here actually refers to the respective brightness ranges of the three color lights. We know that the range is 256, and 256 is the 8th power of 2, which is called 8-bit channel color .
Why is it always represented by the power of 2? Because computers are binary , the power of 2 is used when expressing the number of colors and other quantities.
The color channel here is not a concrete thing in concept. We can compare the three primary color lights to three dimmable desk lamps of different colors, then the channel is equivalent to the dimming button. For the viewer, what is felt is only the image itself, and there is no association between how the three colors are mixed. Just as you only care about the performance of the actors in the movie, and don't think about the process of the director's command during the shooting. Therefore, the role of the channel is "control", not "display" .
Since the Photoshop CS version, support for 16-bit channel colors has been enhanced , which means that more colors can be displayed (ie, 48-bit colors, about 281 trillion).
What are the RGB values of pure black, pure white, reddest, greenest, bluest, and yellowest on the screen?
After thinking about it, we open Photoshop, call up the color palette [F6], and click on the color block at the red arrow. As shown on the left. This color block represents the foreground color. Another color block at the bottom right of it represents the background color. Photoshop **default is black for foreground and white for background**. The shortcut key〖D〗can be reset to the default color.
If the color palette is not in RGB mode, you can click the small triangle button 1-1 RGB color mode in the upper right corner of the color palette, and select the RGB slider in the pop-up menu, as shown in the right figure below.
Let's first look at the hue spectrum of colors. As shown on the left.
The so-called hue refers to the color type of color , namely: red orange yellow green cyan blue purple . The seven colors are joined end to end, forming a closed loop. The starting point of 0 degrees is represented by the X-axis direction, and the expansion is counterclockwise. As shown on the right below.
In this ring, the two colors located at an angle of 180 degrees (that is, the colors at both ends of a diameter of a circle) are called inverted colors, also known as complementary colors. There is a relationship between the two complementary colors. Now we fill in the color in the middle of the circle, as shown on the left below. Assuming that the small box currently in the center of the circle represents the color we want to select, then the small box will move away from yellow when it moves to blue, or it will be far away from blue when it is close to yellow. Just like it's impossible to go both ways on a seesaw, you can't be close to yellow and blue at the same time.
It is white in the middle of the picture above. It can be seen that if you want to get the most yellow, you need to move the color selection box in the direction of the most yellow, and gradually move away from the most blue. When we reach the edge of the yellow part of the ring, we are the yellowest, and we are the farthest from the bluest. From this, it is concluded that yellow = white - blue". Why not white + yellow? Because blue is the primary color light, the adjustment of the primary color light shall prevail. Therefore, the most yellow value is 255, 255, 0. The following figure on the right It can also be concluded that: pure yellow = pure red + pure green.
If an image on the screen is yellowish (especially for screen display, printed matter is different), it cannot be said that there is too much yellow light, but too little blue light . Looking at the chromatographic ring again, we can
visually detect the respective inversion colors of the three primary colors. Red to cyan, green to magenta, blue to yellow .
Reverse color: first obtain the RGB value of this color, and then subtract the existing RGB value from 255. For example, the RGB value of yellow is 255, 255, 0, then by calculation: r(255-255), g(255 -255), b(255-0). Complementary colors are: 0,0,255. It is blue.
Through the above content, we have described the concept of RGB color, of course, we will introduce other color modes later. But remember: RGB mode is the physical color mode of the monitor. This means that no matter what color mode is used in the software, as long as it is displayed on the monitor, the image will end up in RGB. So operating in RGB mode is the fastest, since the computer doesn't have to deal with the extra color conversion work. Of course this speed difference is hard to detect and is only theoretical.