Lesson 1: color composition and color mode

Color Composition What is color composition? Combine two or more colors according to different requirements and the principles of color rules to form a new color relationship. What is color? How do people feel the color? When an object is exposed to light, its information is transmitted to the visual center of the brain through the retina and then through the visual nerves. Therefore, color can be felt only after three steps: Light, eyes, and brain. The concept of color is that light stimulates the eyes and then transmits signals to the brain. Therefore, to see the color, people must have light. Where does light come from? Therefore, a light source is needed. I. Light Source I don't need to say much about the light source. You should also know it. Light sources are divided into natural and man-made light. Natural light is an object that emits light from its own resources (such as the sun). Artificial light depends on other objects (such as electric lights ). 2. object color and solid color The object itself will not emit light. The reason why it can be seen is that the light source color is absorbed and reflected by the surface of the object, reflecting the light color feeling in the vision. Under natural light, an object only reflects the light of one of its wavelengths, while all the light of other wavelengths is absorbed, and this object shows the color of the reflected light. If an object reflects all the colors, we will feel that the object is white. If we absorb all the seven colors, it will be black. In fact, in real life, the color is extremely rich. It is impossible for various objects to reflect only one wavelength of light. It can only reflect much of a certain wavelength of light, light of other wavelengths is reflected less in different proportions. Therefore, the color of an object cannot be an absolute standard color, but only tends to a certain color, at the same time, it has other color components. Therefore, the color of an object is determined by the color of the light source and the ability to absorb and reflect the selected object. The solid color refers to the color of an object. () 3. Three elements of color The three elements of color indicate the color phase, purity (saturation), and brightness. 1. Hue The color phase is the physical and psychological characteristics of the color related to the main wave length. We know from the experiment that visible light of different wavelengths has different colors. Multiple wavelengths of light can be mixed in different proportions to form a variety of colors, but as long as the composition of the wavelength is certain, then the color is determined. Non-color (black, white, gray) does not have the color attribute; all colors (red, orange, yellow, green, green, blue, purple, etc.) are the attributes of the color appearance. They are all colors, sometimes called tones. In a word, the color is the appearance of the color. 2. purity (I .e. saturation) Purity refers to the intensity or purity of the color, indicating the proportion of the gray component in the color phase, expressed in 0%-100% (solid color. 3. brightness Brightness is the relative brightness of the color, which is usually measured by 0% (black)-100% (white. It should be emphasized that the color phase is actually a color ring, which is expressed in angle units. [This post was last edited by Qilian Mountains at, September 17 ,.]

Color Ring .jpg(5.94 KB)

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4. mixed colors
Color has two primary color systems: the primary color of the color light and the primary color of the color. There are three ways to mix colors: addition, subtraction, and neutral.
1. primary colors
Colors that cannot be mixed with other colors are called primary colors. Other colors can be mixed with primary colors.
There are two primary colors: one is the three primary colors of light, and the other is the three primary colors of pigment.
Three primary colors: Red, green, and blue ). (This is what we often call the RGB mode)
Color Colors: magenta, yellow, and Cyan ). (Mcy for printing)

2. Addition and mixing of colors
Addition hybrid refers to the mixture of color and light. Mixed color or multi-color light, mixed out of the new color light, brightness increased, brightness is to participate in the mixing of various colors of brightness and. The more colors you want to mix, the higher the brightness of the new colors. If you mix all the colors together, it becomes a very strong white light. Therefore, we call this hybrid method a positive hybrid or an addition hybrid method.
On the color ring, the distance between the two colors of the mixed colors is closer, moderate, and distant. The new colors are the middle colors of the two colors. The purity of the new color light is high, the purity of the new color light is low, and the remaining color light is mixed. The mixed light is white, and the purity of the new color light disappears. The brightness of the new color is the sum of the brightness of the mixed color.
The color of a computer display is the color of the phosphor light from the fluorescent screen. It is superimposed by the positive mixture. It can display millions of colors. The primary colors are red and green), blue (blue), so it is called the RGB mode.
RGB is an addition mixture, which must be remembered.

Image Description: The two similar colors must be the color in the middle of them. That is to say, the red and green colors must be yellow. You can try it, but they are complementary colors, the complementary colors are white.

3. subtraction and mixing of colors
Subtraction mixing refers to the mixing of pigments, the mixing of pigments, and the reduction of brightness. Therefore, it is called a mixture of negative or subtraction. The properties of pigments, dyes, coatings, and other pigments are different from those of the spectral monochrome light. The color of the pigment is a compound color of the object color. The color of the pigment is the result of partial selection and absorption of the color light in the white light, the result of the reflection and the absorption of the color mixture, but the absorption of some of the mixed increase in light reduction phenomenon.
The two colors mixed on the Color Ring are near, moderate, and distant. The result is the middle color of the two colors. When the two colors are closer, the purity of the mixed colors is reduced. When the two colors are farther apart, the purity of the mixed colors is much lower. If the two colors are the farthest complementary colors, the purity of the new colors disappears, and the brightness decreases to black and gray.
Therefore, to mix a new color with a high purity, You must select a color that is closer to the color ring, such as the green color mixed with yellow green and blue green, the purity must be higher than that of the green mixed with yellow and blue. Because of the different nature of each color material and the mixed time difference, the mixed color result will be affected. Some colors cannot be mixed with other colors.
Theoretically, when three colors are evenly mixed: magenta, yellow, and cyan, all the three colors are absorbed and black is generated. However, in practice, because the color material contains impurities and the formation of brown, so the black pigment (black), to form a CMYK color mode. This is a special color model for computer graphic design. It plays the most important role in pre-printing and is the basis of four-color printing.

4. neutral color mixing
Neutral mixing is a mixture of visual colors Generated Based on Human Visual physiological characteristics. It includes the hybrid method (mean mixing) and Space (well mixing) of the revolving board ).
(1) mixed color of the revolving Board
The color mixing of the flap is a reflection of the pigment. If red and blue are painted on the alicloudcli in a certain proportion, the rotation at a rate of 40-50 or more times per second will show red and purple gray. However, if we mix the red and blue colors with the addition, the light will become light purple and red, and the brightness will increase. The red and blue pigments are mixed by subtraction, and the brightness is reduced. Through the hybrid comparison of the above methods, it is found that the brightness of the color mixed by the method of the swing board is basically the average value of the brightness of the mixed color. Therefore, this hybrid method is called neutral hybrid. The neutral mix of the flap is actually a mixture on the retina. As shown in the above example, the red and blue colors repeatedly stimulate the same area of the retina, red, blue, red, and blue due to the rapid rotation of the revolving board, as a result, red and blue light are mixed on the retina to produce a red and purple gray sensation.
(2) space mixing (parallel mixing)
Due to the limitations of spatial distance and visual physiology, the eyes cannot identify the details of objects that are too small or too far, and different color blocks are shaped into a new color, this phenomenon is called space mixing or well mixing.
If we take a picture of a red or blue dot (or block) through a certain distance, we find that red and blue have become a gray purple. Similarly, only red, yellow, and blue web sites can be used to print a variety of colorful images. In addition to overlapping sites, both the dot and the dot are mixed, this well mixing is called a close-range space hybrid. the distance between a space mixture is determined by the size of the area of the colored points (or blocks) that participate in the mixing. The larger the area of a point or block, the farther the space mixture is formed. The combination of the flap and the well placement is actually a mixture on the retina.
Both are neutral, and the brightness of the new colors is equal to the average value of the brightness of the mixed colors.
You only need to understand this.

 

 

Here is the color composition. The following describes the color pattern.

In Photoshop, it is very important to understand the concept of patterns, because the color pattern determines the color model for displaying and printing electronic images (simply put, the color model is a mathematical algorithm used to represent colors ), that is, how to display or print an electronic image in a computer. Common color modes include bitmap mode, gray mode, two-color adjustment mode, HSB (indicating the color phase, saturation, brightness) mode, RGB (indicating the red, green, and blue) mode, CMYK (indicating blue, foreign red, yellow, and black) mode, lab mode, index color mode, multi-channel mode, and 8-bit/16-Bit mode, the principles of Image Description and reproduction of colors in each mode and the number of colors displayed are different.

In addition to determining the number of colors displayed in the image, the color mode also affects the number of channels and file size of the image. The channel mentioned here is also an important concept in Photoshop. Each Photoshop image has one or more channels, and each channel stores the color Element Information in the image. The default number of Color Channels in an image depends on the color mode. For example, CMYK images have at least four channels to distinguish between blue, magenta, yellow, and black information. In addition to these default color channels, you can also add an extra channel called alpha channel to an image to store and edit the selected area as a mask and add a special channel. An image can have up to 24 channels. By default, there is still one channel in the bitmap mode, grayscale two-color harmonic index color image; RGB and lab images have three channels; CMYK images have four channels.

I. HSB Mode
The HSB mode is defined based on the human eye's observation of colors. In this mode, all colors are described by three features: hue or tone, saturation, and brightness.
1. Hue (h)
The color phase is the physical and psychological characteristics of the color related to the main wave length. We know from the experiment that visible light of different wavelengths has different colors. Multiple wavelengths of light can be mixed in different proportions to form a variety of colors, but as long as the composition of the wavelength is certain, then the color is determined. Non-color (black, white, gray) does not have the color attribute; all colors (red, orange, yellow, green, green, blue, purple, etc.) are the attributes of the color appearance. They are all colors, sometimes called tones.
2. saturation (s)
Saturation refers to the intensity or purity of the color, indicating the proportion of the gray component in the color phase, expressed in 0%-100% (solid color.
3. brightness (B)
Brightness is the relative brightness of the color, which is usually measured by 0% (black)-100% (white.

Ii. RGB mode
The RGB mode is based on the blending principle of three basic colors in nature) the brightness value from 255 to (white) is allocated in each level to specify its color. When the base colors of different brightness are mixed, 256*256*256 colors are generated, about 16.7 million colors. For example, a bright red may have an R value of 246, a G value of 20, and a B value of 50. Gray is generated when the brightness values of the three base colors are equal. When the three brightness values are both 255, pure white is generated. When all the brightness values are 0, pure black is generated. When the three colors are mixed, the color is generally higher than the original brightness value. Therefore, the color generated in RGB mode is also called the color coloring method.

Iii. CMYK Mode
CMYK color mode is a printing mode. The four letters respectively refer to four colors of ink, which are Cyan, magenta, yellow, and black. The CMYK mode is essentially the same as the RGB mode, except that the color generation principle is different. In the RGB mode, colors are generated by the color light emitted by the light source, in CMYK mode, light is directed to paper with different proportions of C, M, y, and K ink. After some spectra are absorbed, light is reflected to the human eye to produce color. As C, M, y, and K are mixed in color, as the four components C, M, y, and K increase, less light is reflected into the human eye, the brightness of light is getting lower and lower. All the methods for generating colors in CMYK mode are also called the color-light Subtraction Method.

Iv. Lab Mode
The prototype of the lab model is a color measurement standard set by the CIE Association in 1931. It was redefined and named cielab in 1976. This mode solves the color difference caused by different display and printing devices, that is, it does not depend on the device.
The LAB color is represented by a brightness component L and two color components A and B. The value range of L is 0-100. component A represents a spectral change from green to red, and component B represents a spectral change from blue to yellow, the value range of A and B is-120-120.
The lab mode has the widest range of colors and can contain all colors in RGB and CMYK modes. The CMYK mode contains the least color, but some colors displayed on the screen cannot be achieved on the print.

5. Other color Modes
In addition to the basic RGB mode, CMYK mode, and lab mode, Photoshop supports (or processes) other color modes, these modes include bitmap mode, gray mode, two-color adjustment mode, index color mode, and multi-channel mode. And these color modes have their own special purposes. For example, a gray-mode image only has a gray value but no color information. Although color can be used in the index color mode, compared with the RGB and CMYK modes, few colors are available. The following describes the color modes.
1. bitmap mode
Bitmap uses two colors (black and white) to represent pixels in an image. Bitmap images are also called black and white images. Because its depth is 1, it is also called an image. Since the bitmap mode only uses black and white to represent the pixels of an image, many details are lost when converting the image to the bitmap mode. Therefore, Photoshop provides several algorithms to simulate lost details in the image.
When the width, height, and resolution are the same, the image size in bitmap mode is the minimum, which is about 1/7 in gray mode and less than 1/22 in RGB mode.
2. grayscale (grayscale) Mode
In grayscale mode, up to 256 levels of gray scale can be used to present images, making the transition of images smoother and more delicate. Each pixel of a grayscale image has a brightness value between 0 (black) and 255 (white. The gray value can also be expressed by the percentage covered by the black ink (0% equals white, 100% equals black ). Images generated using a black fold or grayscale scanner are often displayed in gray scale.
3. duotone Mode
The two-color adjustment mode uses 2-4 color inks to create two-color adjustment (2 colors), three-color adjustment (3 colors), and four-color adjustment (4 colors) combine the color order to form an image. In the process of converting a grayscale image to a two-color adjustment mode, you can edit the tones to produce special effects. The main purpose of the dual-Color adjustment mode is to use as few colors as possible to display as many color layers as possible, which is very important to reduce the printing cost, because during printing, each increase in tone requires a higher cost.
4. Indexed color mode
The indexing color mode is commonly used in online and animated images. When a color image is converted to an indexed color, it contains nearly 256 colors. The indexed color image contains a color table. If the color of the original image cannot be expressed in 256 colors, Photoshop selects the most similar colors from the available colors to simulate these colors, which can reduce the size of the image file. Used to store colors in images and create color indexes for these colors. The color table can be defined during conversion or modified after the image is indexed.
5. Multi-channel (multichannel) Mode
The multi-channel mode is very useful for images with special printing requirements. For example, if an image uses only one or two colors, the multi-channel mode can reduce the printing cost and ensure the correct output of the image color.
6. 8-bit/16-bit channel mode
In gray RGB or CMYK mode, you can use a 16-bit channel to replace the default 8-bit channel. By default, the 8-bit channel contains 256 levels. If it is increased to 16, the number of levels for each channel is 65536, so that more color details can be obtained. Photoshop can recognize and input 16-bit channel images, but there are many limitations on this image, all filters are not available, and the other 16-bit channel mode images cannot be printed.

6. color mode conversion
To output images correctly in different scenarios, you sometimes need to convert an image from one mode to another. Photoshop converts the desired color mode by executing the commands in the "image/mode" sub-menu. This color mode conversion sometimes permanently changes the color value in the image. For example, when an RGB image is converted to a CMYK image, the RGB color values outside the CMYK color gamut are adjusted outside the CMYK color gamut to narrow the color range.
Because some colors will lose part of the color information after conversion, it is best to save a backup file for it before conversion to restore the image as necessary.
1. convert a color image to a grayscale image
When you convert a color image to a grayscale image, Photoshop will discard all the color information in the source image and only retain the gray level of the pixel.
The gray mode can be used as an intermediary between the bitmap mode and the color mode.
2. Convert images in other modes to bitmap Modes
Converting an image to a bitmap mode reduces the image color to two types, which greatly simplifies the color information in the image and reduces the file size. To convert an image to a bitmap mode, you must first convert it to a grayscale mode. This removes the color and saturation information of the pixel and only retains the brightness value. However, since there are only a few editing options available for bitmap images, it is best to edit the image in grayscale mode and then convert it.
After the bitmap mode image edited in grayscale mode is converted back to the bitmap mode, it may look different. For example, if the bitmap mode is a black pixel, it may become gray after being edited in grayscale mode. If the pixel is bright enough, it becomes white when converted back to the bitmap mode.
3. convert other modes to the Index Mode
When a color image is converted to an indexed color, many colors in the image are deleted, and only 256 of the colors are retained, that is, the number of standard colors supported by many Multimedia Animation applications and web pages. Only images in the gray mode and RGB mode can be converted to the index color mode. Since the gray mode itself is composed of a gray scale of 256, there is no significant difference in color or image size after being converted to the index color. However, after converting an RGB image into an indexed color pattern, the size of the image will be significantly reduced, and the visual quality of the image will be compromised.
4. Convert the RGB image to the CMYK mode.
If you convert an image in RGB mode to CMYK mode, the color in the image is divided into colors, and the color gamut is limited. Therefore, if the image is in RGB mode, it is best to edit it in RGB mode and convert it to a CMYK image.
5. Use lab mode for Mode Conversion
In the color mode that Photoshop can use, the lab mode has the widest color gamut, including all colors in the RGB and CMYK color gamut. Therefore, the use of lab mode for conversion will not cause any color loss. Photoshop uses the lab mode as the internal conversion mode to convert different color modes. For example, when converting an RGB image to the CMYK mode, the computer first converts the RGB mode to the lab mode, and then converts the lab mode image to the CMYK mode image.
6. convert other modes into multi-channel modes
The multi-channel mode can be obtained by converting the color mode and deleting the color channel of the original image.
To convert a CMYK image to a multi-channel mode, you can create a special premix ink, which is used to replace or supplement the four-color printing ink; the special color channel is a special color channel for adding preview special colors to the image .) The image.
You can convert an RGB image to a multi-channel mode to create an image consisting of blue, red, and yellow.
Deleting a channel from an RGB, CMYK, or lab image automatically converts the image to a multi-channel mode. The original channel is converted into a special channel.

 

 

You may not be able to read a lot of text, but someone may ask why I cannot find the HSB mode in Ps "image/mode, PS does not have such a pattern, because it is defined based on the human eye's observation of color and has nothing to do with the output. But we use it for color every day. Next I will talk about HSB, because it is the origin of all the color patterns. If you understand it, it is not difficult to understand other models. As I said before, we use it every day. Some people may not understand it yet. Open ps, double-click the foreground color, and a color picker will appear. We can see that we are in the HSB mode to pick up the color. Now we use the color phase (h) To take the color, and the position is 0 degrees. As I mentioned earlier, the color phase is a ring, 0 degrees is red (r = 255 ). We can drag the control point to change the color. We can also select the saturation (s) to pick up the color. You can also clear the brightness (B) first, and control the brightness through control points. Download(25.83 KB) We can also try to use RGB to retrieve the color. Download(25.27 KB) In the lab mode, we can see that the color gamut of the lab is the widest. Download(26.07 KB) As mentioned above, it is described by three features: hue, saturation, and brightness. A bit of PS-based first reaction may come up with "hue/saturation". In fact, "hue/saturation" is a color tool based on the HSB mode. These color tools will be mentioned one by one later, I will not talk about it here.

Color saturation. jpg(21.41 KB)

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