Color mode
It is an algorithm and presentation form of color representation in the digital world, and it is a compulsory course for color application.
The following mainly interprets RGB, HSB, HSL, CMYK, LAB, grayscale mode, index mode, and analyzes it in combination with application scenarios, refreshing your cognition of color mode, and laying a solid foundation for the scientific application of color.
01 rgb
1-1 Origin of RGB
RGB mode is the optical tricolor mode, R stands for red, G stands for green, and B stands for blue. Any color that can be seen by the naked eye in nature can be made up of a mixture of these three colors; Increasing the intensity of each color of light produces a different bright color, which will eventually result in white, hence the addition color mode.
Popular expression: RGB is mixed in a way that is like having red, green, and blue lights, when their light is superimposed on each other, and the brightness is equal to the sum of the brightness of the three, and the more mixed the brightness, the higher the brightness.
RGB RGB has 0-255 [256] color levels: RGB is weakest at 0 "light" at the same time, which is equivalent to turning off the brightest light RGB [0; 0;0], while at 255 the "lamp" is brightest rgb [255; 255;255], that is, when RGB stacks 255 from 0, it finally gets white.
When RGB three values are equal, there is no change in hue and purity, only a change in lightness, which is called grayscale. The smaller the gray value, the darker the gray scale, and the larger the gray value, the brighter the gray scale.
1-2 RGB examples
In life, the luminous principle of a computer monitor is actually the superposition principle of RGB. Why are some screens cooler and some warmer? In fact, it controls the RGB display ratio, and if you want the screen to be cold, you can increase the cold tone. However, the bottom principle that affects the color tendency of the screen and the intensity of the light is the arrangement of the RGB of the light-emitting board, that is, the arrangement of the recent boiling "Zhou Dongyu". If you are interested in the underlying principle of the light-emitting plate, you can consult the relevant information by yourself.
Screen Wallpaper For a deeper understanding of RGB mode, let's take another example from life:
The brightness of the light tube and bulb dims after a period of time, which is actually talking about the life of the emitter. The blue wavelength in RGB is the shortest, and if it is used for a long time, the proportion of RBG superposition is unbalanced: it is affected by the material of the luminaire (such as the light transmission, refraction and reflection of glass are stronger than that of wood), so as to absorb and dilute the blue light with short wavelength (the penetration is weak when the wavelength is short).
Once the RGB is out of balance, the white light obtained by the RGB superposition will be turbid, and then the CMY will be superimposed to obtain CMY, which will be mixed by impurities such as materials and physical conditions, and finally obtain black. Therefore, it is generally seen that the edges of discarded bulbs and light pipes are often accompanied by black and gray, which is the fate of RBG in the application of luminaires.
In summary, the lifetime of the luminaire is affected by the proportion of RGB used, the material of the luminaire, and the physical conditions.
1-3 RGB applications
The sun's rays at noon, white clouds, and rainbows (RGB dispersion) are all natural phenomena of RGB.
Dispersion. RGB is widely used and ubiquitous in life: Screen: mobile phone displays, computer displays, slides, and many more can be seen everywhere; Internet design: RGB is the standard mode, web design, APP design, visual design, image design, etc.; Graphics post-production: * style shaping, design style debugging, **scene processing, etc.; Medical: imaging, X-ray, CT, ultrasound, etc., such as human body dissection, bone architecture; Image: film, video, projection, self-a**, etc., such as photo; Industrial: Automotive painting, instrument color matching, etc.
02 cmyk
2-1 Origin of CMYK
CMY is the intermediate color obtained by mixing the three primary colors RGB: Cyan Cyan, Magenta Magenta Magenta, Magenta, and Yellow Yellow. More and more colors are added to make the color cloudy, the purity is constantly decreasing, and when the RGB keeps dropping from 255 to 0, it will eventually get black, so the CMY mode is the subtractive mode, and the corresponding RGB mode is the additive mode.
CMYK will never reach pure black due to the infinite close to pure black obtained in the color mixing mode, that is, the black ink that CMY adjusts in the printing scene will never get pure black. In order to achieve pure black, make it more penetrating and more perceptible to the human retina, black black was added to the CMY mode. In order to distinguish it from blue, the abbreviation truncates the last letter K as a benchmark, which is the origin and attribute of CMYK.
2-2 rgb vs cmyk
In summary, CMYK is also known as the printing color mode. Compared with RGB mode, RGB mode is a color mode in which the screen displays illuminated colors, and the content on the screen can still be seen in a dark environment (in case of troubleshooting); CMYK is a color mode used for printed matter that relies on reflection, which is made by sunlight or light shining on the object, and then reflecting to the retina, before seeing the content, which requires an external light source; You can't read the newspaper if you're in a dark room.
In PS, CMYK is percentage-controlled, while RGB is made up of 0-225 [256] color levels, each of which is arranged and combined:
cmyk 100 3=1,000,000；
rgb 2563=16,777,216；
It can be seen that the color value of RGB is richer than that of CMYK, so when the design publication in RGB mode is converted to CMYK mode, that is, the 16777216 drops to 1000000, then the color threshold decreases, and then the retinal perception tells us that the color purity and brightness under the same hue are significantly reduced. Generally speaking, the color has become darker, and the color is not brighter, which is the origin of what we often call "distortion".
Therefore, if you want to print a publication that is not easy to distort or has a small color aberration, it depends on 3 important factors:
1.Ink purity:The ink purity is high, and the color difference of the products printed by the printing machine is naturally small.
2.Mode of printing:That is, RGB, CMYK, and the lab discussed below. How can I print a publication in RGB mode? In fact, it is what we often call laser printing, why is laser printing not easy to distort? (You can think about it, our comment area**.)
3.Print Material:For example, the reflectivity of glass is clearer and brighter than that of wood.
2-3 CMYK application
Printing: publishing and printing, packaging and decoration printing, news printing, ** printing, stationery printing and parts printing, etc., such as newspapers, magazines, books, brochures;
Graphics post-production: style shaping, design style application, scene application tone processing, etc.
03 RGB&cmyk Summary
3-1 RGB mode
Also known as the three primary color mode, it is the source of all modes, RGB is superimposed on each other to finally get white, and is often used in the screen and imaging according to its superimposed luminous properties.
3-2 CMYK mode
Also known as printing mode, the intercolor obtained by RGB superposition. Because the three colors of CMY are constantly mixed, the color will be cloudy, and finally it will be close to black. In order to achieve pure black in the printing ink, black is added: the abbreviation takes the last letter K, i.e. CMYK.