RGB color Mode

We use a magnifying glass to view the computer monitor or TV screen, we will see a large number of red green blue Three colors of the dots. The left figure below is the local enlargement of the left image. All the colors on the screen, that is, all the image content we see, are all made up of them.

Now we open the following image in Photoshop, open the way through the menu "file _ Open" or use the shortcut key 〖ctrl_o〗 (the instructions for the shortcut key will appear in the future course, now do not understand and does not matter). You can also drag the image directly from the Windows directory to Photoshop. If the Photoshop window is obscured or minimized, you can also drag to the button on the taskbar, wait until the Photoshop window pops up, and then drag into the window.

Press 〖f8〗 or from the menu "window _ Info" to pull out the information palette. The following is the right figure. Then try moving the mouse in the image and you will see that the values are constantly changing. Notice that when you move to the blue area, you see a higher number of B, and a higher value for r when you move to the red area.

All the colors on the computer screen are mixed in different proportions by the three shades of red, green and blue. A set of red green blue is a smallest display unit. Any color on the screen can be recorded and expressed by a set of RGB values. So, the leftmost picture seen below is actually made up of three parts of the right-hand side.

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So this red Green blue, also known as the three-color light, in English is the R (red), G (green), B (blue). RGB can be imagined as Chinese food inside the sugar, salt, msg, any one dish is mixed with these three kinds of spices.

In the production of different dishes, the proportion of the three is not the same, and may even be different. Therefore, in different images, RGB components are not the same, there may be some in the image of R (Red) more, some B (blue) components more.

When cooking, the recipe will prompt similar "sugar 3 grams, salt 1 grams", to indicate how much seasoning, in the computer, RGB so-called "how much" refers to the brightness, and the use of integers to express. Normally, RGB has 256 levels of brightness, with numbers as from 0, 1, 2 ... Until 255. Note that although the highest number is 255, but 0 is also one of the values, so a total of 256 levels. As it was 11 from 2000 to 2010.

According to the calculation, the 256-level RGB color can combine about 16.78 million kinds of color, namely 256x256x256=16777216. Usually also referred to as 16 million-color or million-color. Also known as 24-bit color (2 of the 24-second side).

The 24-bit color also has a more strange name is 8-bit channel color, why do you call it?

The so-called channel here, in fact, refers to the brightness range of three kinds of shade, we know its range is 256,256 is 2 8 Times Square, is called 8 bit channel color.

Why do you always use 2 of the second party? Because the computer is 2, it uses 2 of the time to express the number of colors and other quantities.

The color channel here is not a specific thing in concept. We can compare the Sanyuan shade to three different colors of adjustable light, then the channel is equivalent to the dimming button. To the viewer, it is the image itself that is felt, not how the three colours are mixed. Just as you care about the performance of the actors in the movie, you don't want to be in the process of directing the film. Therefore, the function of the channel is "control", not "show".

The above is a color channel that is not exactly the same concept as the image channel in the following tutorial.

Increased support for 16-bit channel colors starting with the Photoshopcs version, which means that more colors can be displayed (48-bit color, about 281 trillion). RGB individual brightness value is 2 of 16 times, equal to 65536,65536 three times Square is 281474976710656. But the number of colors that the human eye can tell is less than 24 bits of 16.78 million color. So the higher the number of colors in the eyes of the people there is no difference.

A color, such as r32,g157,b95, or r32g157b95, can be expressed by using the letter R,g,b plus their respective values. Sometimes for the sake of convenience also omit letter write 32,157,95 (delimited symbol cannot be marked wrong). Then the order of representation is RGB. There is also a 16-way expression that will be described later.

So how do these numbers and colors correspond, or how can you tell from a set of numbers?

In fact, it is difficult to judge the color directly from the numerical value for beginners and even veteran. Because it takes a certain amount of experience to consider the mixing of three of different colours. But this ability is not a must. Even if it can't be done, there is no harm in the future.

For a separate R or G or B, when the value is 0, the color does not glow, and if 255, the color is the highest brightness. This is like dimming lamp, the number 0 is equal to turn off the lights, the number 255 is equal to the dimming knob open to the largest.

Now leave the tutorial to think about: black on the screen, pure white, the most red, the greenest, the most blue, the most yellow RGB value is how many?

After thinking about it, we open Photoshop, bring up the color palette 〖f6〗, and click on the color block at the Red Arrow. The following is the left figure. This color block represents the foreground color. Another color block at the bottom right of it represents the background color. Photoshop defaults to the foreground color black, white background. The shortcut key 〖d〗 can be reset to the default color.

0101 If the color palette is not RGB, you can click on the color palette in the upper right corner of the small triangle button, in the pop-up menu select RGB Slider, the following right figure.

Pure black, because there is no shade on the screen. The equivalent of RGB three colors are not luminous. So the black RGB value on the screen is 0,0,0. We can adjust the slider or directly enter the number, you will see the color block into black. The following is the left figure.

And White is the opposite, is RGB three kinds of shade are sent to the strongest brightness, so pure white RGB value is 255,255,255. The following figure.

The most red, meaning that only red exists, and the strongest brightness, green and blue are not luminous. So the most red value is 255,0,0. The following is the right figure.

Similarly, the greenest is 0,255, 0, and the blue is 0, 0,255. Did you do the right thing? If not please repeat the previous content.

So what's the yellow one? RGB does not contain yellow items. Put the problem aside for a moment, let's look at the hue spectrum of the color first. The following is the left figure.

The so-called hue refers to the color of the type of color, is: red orange yellow green cyan blue purple. These seven colors are connected to each other, forming a closed ring. Represents a 0-degree starting point in the X-axis direction and unfolds counterclockwise. The following is the right figure.

In this ring, the two colors at the angle of 180 degrees (that is, the color at each end of a circle), called the inverse color, also known as the complementary color. Complementary between the two colors is the relationship between the extinction, now we put the color of the center of the ring filled, the following left figure. Let's say the small box at the center of the circle is the color we want to choose, so the small box moves in blue and goes away from the yellow, or close to the yellow and away from the blue. Just as it is impossible to go both ways on the seesaw, you cannot approach both yellow and blue at the same time.

In the middle of the above picture is white, you can see that, if you want to get the most yellow, you need to move the color box to the yellow direction, but also gradually away from the most blue. When it reaches the edge of the yellow part of the ring, it is the most yellow, and we are farthest from the most blue. As a result, yellow = white-blue. Why not white + yellow? Because the blue is the primary color light, should be based on the adjustment of the original shade. Therefore, the yellow number is 255,255, 0. The following is the right figure. can also be drawn: pure yellow = pure red + pure green.

If a picture on the screen is yellow (especially if the screen shows a different print), it cannot be said that there is too much yellow light, but it should be said that there is too little blue light.

Looking at the chromatographic rings, we can visually invert the colors of the three primary colors. Red to cyan, green to magenta, blue to yellow. The following figure.

In addition to the visual, can also be calculated to determine any color inversion color: First get the color of the RGB value, and then use 255 respectively minus the existing RGB value can be. 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's blue.

For a picture,

If the brightness of r is increased individually, the equivalent of red light is increased. Then the picture will be red.

If the brightness of B is increased individually, the equivalent of blue light is increased. Then the picture will be blue.

Through the above content, we talked about the concept of RGB color, of course, we will also introduce other color patterns. Remember, however, that 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 eventually appears in RGB mode. Therefore, the use of RGB mode is the fastest, because the computer does not need to deal with additional color conversion work. Of course, this speed difference is difficult to detect, but theoretically.

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