Relationship between color temperature, color light and color

color temperature

The most common index of spectral quality of light source. Color temperature is defined as absolute black body. When the radiation of the light source is exactly the same as that of the absolute blackbody in the visible region, the temperature of the blackbody is called the color temperature of the light source. Low color temperature light source is characterized by relatively more red radiation in energy distribution, which is usually called "warm light"; After the color temperature rises, the proportion of blue radiation in the energy distribution increases, which is usually called "cold light". The color temperature of some common light sources is: standard candle light is 1930K (Kelvin-day); Tungsten lamp 2760-2900K；; The fluorescent lamp is 3000 k; Flash 3800 k; The sunshine at noon is 5400 k; Electronic flash 6000 k; The blue sky is 12000- 18000K.

When discussing the light used in color photography, photographers often mention the concept of "color temperature". What exactly does color temperature mean? As we know, the light usually seen by human eyes is composed of the spectra of seven colors of light. But some are blue and some are red. Color temperature is a method specially used to measure and calculate the color composition of light. It was founded by the British physicist Lord Kelvin at the end of 19. He developed a set of color temperature calculation method, the specific standard is based on the wavelength emitted by a blackbody radiator.

Kelvin believes that if a pure black object can absorb all the heat falling on it without loss, and at the same time release all the energy generated by heat in the form of "light", then the wavelength of its maximum radiation intensity will change with the change of temperature. For example, when the thermal stress on the blackbody is equivalent to 500-550 degrees Celsius, it will turn dark red (the radiation intensity of a certain red wavelength is the highest), and it will turn yellow when it reaches1050-150 degrees Celsius ... Therefore, the color composition of the light source corresponds to the temperature on the blackbody. Color temperature is usually expressed in kelvin temperature (k), not in degrees-days. In the process of striking iron, black iron gradually turns red in the furnace temperature, which is the best example of blackbody theory. Usually, the tungsten wire in the bulb we use is equivalent to this black body. The calculation method of color temperature is based on the above principle, and K is used to correspond to the color representing the maximum wavelength of an object when it radiates at a specific temperature.

According to this principle, the color temperature of any light is equivalent to the "temperature" when the black body emits the same color. Color is actually a psychological and physiological function. All color impressions are caused by intermittent spectral reactions on the eyes, so color temperature is only used to express the visual impression of color.

colour

classify

Colors can be divided into achromatic colors and colored colors. The former is black and white. Gray, the latter such as red, yellow, blue and other colorful.

Having color refers to having a certain or certain hue in the spectrum, collectively referred to as hue. On the other hand, achromatic color has no hue.

Achromatic colors have lightness and darkness, which are white and black respectively, also called hue. Color representation is very complicated, but it can be determined by three sets of characteristic values. One is hue, that is, hue; The second is light and shade, that is, lightness; The third is strong color, namely purity and chromaticity. Brightness and chroma determine the state of color. Three attributes called color. The color state in which lightness and hue are combined into two lines is called hue. Some people understand lightness as hue, which is not comprehensive. Let me know the color first:

Three attributes of 1. color

Hue: abbreviated as H, which indicates the characteristics of colors and is a necessary name to distinguish colors, such as red, orange, yellow, green, cyan, blue and purple. Hue has nothing to do with the strength and lightness of color, but simply expresses the difference of color appearance.

Value: V for short, indicating the intensity of color, that is, the brightness of colored light. Different colors reflect different amounts of light, which will produce different degrees of brightness.

Chromaticity: c, which indicates the purity of color, that is, the saturation of color. Specifically, it indicates whether the color contains white or black components. If a color does not contain white or black components, it is the "pure color" with the highest chroma; If it contains more white or black components, its chromaticity will gradually decrease.

2. Two primary colors

All the colors we see are composed of three colors or three colors, and they cannot be separated into other color components, so they are called three primary colors.

3. Optical primary colors

They are red, green and blue. White light can be obtained by mixing these three colors of light. For example, the light emitted by neon lights is colored, which can directly stimulate people's visual nerves and make people feel the color. The colors we see on TV screens and computer monitors are all composed of RGB.

4. The three primary colors of an object

They are cyan, magenta, red and yellow respectively. If you mix three colors, you will get black. Unlike neon lights, objects can emit colored light by themselves. It depends on the illumination of light, and then reflects some light to stimulate vision and make people feel colored. CMY three-color mixing, although you can get black, but this black is not pure black, so you should add black when printing, and the four colors should be carried out together.

[Edit this paragraph] brightness

When it comes to lightness, we should start with achromatic color, because achromatic color is only one-dimensional and argumentative. The brightest is white, and the darkest is black. Different degrees of gray scale between black and white have the performance of light and dark intensity. If divided at a certain interval, it constitutes the scale of light and shade. Color depends on its own lightness value, and it can also be adjusted by adding and subtracting gray and white tones.

Japanese color matching system (P.C.C.S) uses nine levels, while Mense uses eleven levels to represent light and shade. Both of them use a series of numbers to indicate the rapid increase of brightness. The brightness of an object's surface is related to its reflectivity. More reflection, less absorption, is light; On the contrary, it is dark. Only 100% reflected light is ideal white, and 100% absorbed light is ideal black. In fact, there is no such ideal phenomenon around us, so people often take the most ideal white magnesium sulfide crystal plane as the standard of white. In the P.C.C.S system, black is' 1, gray tone is 2.4.3.5, 4.5.5, 6.5, 7.5, 8.5, and white is 9.5. The closer to white, the higher the brightness, and the closer to black, the lower the brightness. There are seven popular classifications: highest, highest, slightly higher, medium, slightly lower, lower and lowest. Among these nine levels, if you add their classification levels, that is, 2, 3, 4, 5, 6, 7.8 and 9, you get seventeen brightness levels.

There are shades of color, and the brightness of its purity is expressed by the brightness corresponding to achromatic color gray tone. Brightness is generally marked with vertical lines. The top is white, the bottom is black, and then it is graded according to the feeling and discharged into gray tones. This vertical axis of light and shade, called achromatic color axis, is the central axis of colored solids.

[Edit this paragraph] Tone

Having color means including hue, that is, several color families such as red, yellow and blue, which are called hue.

The original basic colors are: red, orange, yellow, green, blue and purple. Insert one or two intermediate colors in the middle of each color, and their head and tail tones are red, orange-red, yellow-orange, yellow-green, green, green-blue, blue-green, blue-purple, purple and red-purple. Adding an intermediate color to red and purple can produce 12 basic tones.

The tone changes of these twelve tones are consistent in spectral color sense. If we further find out the middle color, we can get 24 shades. If the red, orange, green, blue and purple bands of the spectrum are circled again, and a half band is inserted between red and purple to form an annular hue relationship, it is called a color phase ring. Take the middle color between the basic colors and get the 12 hue potential ring. In addition, there is a 24-color ring. In the circle of the color phase ring, the tones are arranged at different angles, so the interval between each tone of the twelve color phase rings is 30 degrees. The interval of each hue of the 24-color ring is 15 degrees.

The P.C.C.s system has formulated a more standardized unified name and symbol for hue. Among them, red, orange, yellow, green, blue and purple refer to their "positive" colors (of course, the understanding of the so-called positive color varies from place to place). Positive color is represented by a single capital letter, equal color mixed color is represented by two capital letters in parallel, unequal color mixed color is mainly represented by capital letters, and final color is represented by lowercase letters. The only exception is that Zilan uses V instead of BP. V is the first letter of violet. It is convenient for beginners to use and remember correctly by coding the letters in hue. It is obvious that the Japanese divide and assign color names in this way, which is in line with Mencel's ten tones and twenty tones. Mencel system is based on red, yellow, green, blue and purple, which is called yellow red. Therefore, the 24 colors of P, C, C and S are also divided into ten categories.

[Edit this paragraph] Chromaticity

A hue, there are strong and weak points. Take Zheng Hong as an example, there are bright pure red with no impurities, "withered roses" with astringency and dryness, and relatively pale pink. They all have the same hue, but the strength is different, which is generally called (SA+URA+LON) or chromaticity. Chroma is usually called high or low. The higher the chroma, the purer and brighter the color. The lower the chromaticity, the more astringent and turbid the color. Solid color is the highest chroma level. Said chromaticity, generally expressed by horizontal axis. Taking the longitudinal axis of achromatic color as a point, it extends outward in a certain hue direction of the color circle, and makes several levels according to the chromaticity from low to high. P, C, C and S systems are divided into nine levels, with S as the scale unit. The minimum value is. The maximum value is G S. The closer to the achromatic longitudinal axis, the lower the chromaticity. There is no hue on the achromatic axis, so it can be said that the hue is O S, far away from the achromatic axis, with high chroma, and the end point is pure color, which is the hue of the color in the spectrum. Chromaticity is classified as follows: according to the brightness of purity, find the corresponding gray tone, divide it into nine equal parts (according to the feeling), add one part to the solid color, and deduct a part of the color from one part. So you get eight continuous shades of solid color. 5 S is to deduct 4/9 pure color and 4/9 ash; ISG removed 8/9 purity, increased 8/9 solid color and increased 8/9 ash. The popular division method corresponds to the nine-level chromaticity. It is divided into five grades: high, slightly high, medium, slightly low and low.

[Edit this paragraph] Stereo color scale

Ostwald color scale

We sort out the lightness, hue and color obtained after the above mixing under white light, and choose from bottom to top. The color scale on each cross section is the same, and the color scale on the upper cross section is higher than that on the lower cross section. Then black, white and gray are taken as the central axis, and the center is outside, so that the color code purity on the same cylinder is the same, and the purity on the outer cylinder is higher than that on the inner cylinder. Outside the central axis of the team, the hue of each vertical section is the same, so that the hues of red, orange, yellow, green, cyan, blue and purple on different vertical sections are arranged clockwise from the central axis of the ring, thus organizing thousands of color codes neatly into three-dimensional color codes. At present, the three-dimensional color scale with great influence is ostwald color scale and Mencel color scale.

honey

Terminology of dye detection. Under the condition of the same dyeing depth, the deviation degree of the color of the dye to be tested and the color of the standard dye.

Include differences in hue, brightness and saturation.

The degree of color and light deviation is divided into five grades: (1) approximation, and there is no difference between the two dyed samples by visual inspection alternately. (2) Microscopically, there seems to be a difference in color and light between the two dyed samples alternating left and right. (3) Slightly, it is easy to distinguish the color difference between the two dyed samples by visual inspection alternately from left to right. (4) Compared with the two dyed samples, there are obvious differences in visual inspection. (5) In contrast, the two dyed samples basically show two colors.