A way to coordinate the color of the screen with Brown Paper Takeaway Bags

A way to coordinate the color of the screen with Brown Paper Takeaway Bags

 

Although printing can reproduce tens of thousands of colors, but because of the use of subtraction for color, the brightness of the colors will be weakened, and some bright colors are difficult to be expressed in print. On the other hand, the screen, due to the addition of color technology, in the range of color expression, is indeed richer than printing. This is why colors that look beautiful on screen cannot be reproduced in print, resulting in a difference in color between screen and print. The solution is either to improve the composition of ink and paper so that fresher, purer colors can be reproduced, but this does not happen overnight. Another approach is to narrow the gamut of the screen to fit the print, so that what the screen sees is what the print sees.

 

The gamut is the maximum range of colors that a device can record or reproduce. The color gamut of human eyes is all visible light, which is within the wavelength range of 380 to 780. The color gamut of printing is composed of paper and ink. Different paper and ink matching have different printing color gamut, and the color gamut of Pantone is different from that of book paper and DIC. Others, such as screens, scanners, printers, etc., also have their own gamut. It is practical to master the gamut of a device, because a device cannot record or copy colors outside the gamut. For example, normally, the human eye cannot see colors in infrared or X-ray light, and some colors that are easy for the human eye, like various metallic colors, are not easy to record in a scanner. The best we can do is to have the gamut of one device simulate the gamut of another. How to make the color gamut of the two devices seem similar to the human eye in the simulation process is an important theme of color production.

 

Conduct color management and establish color standards

To produce color, it is necessary to establish a set of standards for the representation and transmission of color. Current popular color management systems such as LinoColor and Agfa's Phototone are developing in this direction. Through a set of standard specifications (ICC reference file) describing the color gamut of devices, color computing software is used to perform uniform color gamut conversion operations to reduce the color data transfer process. Color deviation and distortion due to color gamut and specifications. To implement these color management systems, the first step is to find out the color gamut characteristics of the device. The most commonly used method to describe the color gamur, is CIELab is the International Lighting Association, according to the visual characteristics of the human eye, the light wavelength into brightness and hue of a set of description color data, where L is to describe the brightness of the color, a represents the description of the degree of color red and green, b represents the description of the degree of color yellow and blue. In the CIELab color space, every color visible to human eyes has a position belonging to that color. By comparing the distance between the two color positions, we can determine the approximation degree of the two colors.

 

Since the visible light spectrum is the basis of this data, it can cover the colours produced by screens and printing, and can also be used to represent the gamut of the human eye.

 

For example, to describe the gamut of a printer, first print some test bars from the printer. These bars include major colors and colors that are difficult to reproduce. Then, the CIELab data on the bars are measured with a spectrometer. It also includes the production characteristics of the equipment, such as black plate characteristics, dot expansion, and so on. With the reference file of the devices, the color computing software can refer to the characteristic data of the two devices, and put the color gamut of the devices into the CIELab color space for comparison and conversion, so as to obtain a better simulation effect. This technology has reached the stage of production application, the most used is to simulate printing color gamut on the screen, and to simulate printing color gamut on the printer. Since the color gamut of the screen is larger than that of printing, the simulation in this case is also called gamut compression simulation. The whole simulation process is based on the data in the control file as the calculation basis, so the generation and management of the control file is the most important work.

 

Color management system assumptions

 

Is a color management system in place, that is, to produce the desired color results? To answer this question, you must understand the assumptions behind color management systems. The main job of the color management system is to simulate another known color gamut data on the CIELab space according to one known color gamut data. Therefore, it must be assumed that both color gamut data remain in the same state when the color gamut data is recorded. That is to say, the production state for establishing the equipment reference file must be the same as the production state for calculating the gamut. If the reference file established yesterday can not be compared with today's equipment, the production state is constantly floating, the color management system is not able to play a role in reducing the deviation. An unstable production process may even cause the color management system to amplify the color deviation. Therefore, the color management system is more suitable for the customers who have design, color separation, proofing and printing at the same time, because it is easier to control the variables of the production process in the same plant.

 

Color is not only an element of design, but also the production of receiving standards, even if the customer reluctantly accept a color unsatisfactory printing, the next may not patronize. Many companies lose important customers because of color quality problems. It can be seen that mastering the law of color presentation and controlling color quality is a technology that must be mastered in production. Only with advanced equipment without good technical cooperation, in the fierce industry competition, inevitable elimination of the fate.

 

Color principle

When it comes to painting and image, it is natural to talk about color. All patterns are composed of basic shapes and colors. Color forms an important part of our image processing.

 

(1) The principle of three primary colors

In the physics class of middle school, we may have done experiments with prisms. After passing through the prism, white light is decomposed into a spectrum of various colors gradually transitioned into red, orange, yellow, green, cyan, blue and purple, which is the visible spectrum. Among them, human eyes are the most sensitive to red, green and blue. Human eyes are like a three-color receiver system, and most colors can be synthesized by red, green and blue in different proportions. Most monochromatic light can also be broken down into red, green and blue. This is the most basic principle of colorimetry, namely the principle of three primary colors. The three primary colors are independent of each other, and no one primary color can be combined with the other two colors. Red, green and blue are the three primary colors, which combine the widest range of colors. The three primary colors red, green and blue are combined in different proportions to combine colors called additive colors.

 

Red + green = yellow
Green + blue = cyan
Red + blue = magenta
Red + green + blue = white

Yellow, cyan, magenta are made from the mixture of two and colors, so they are also called additive secondary colors. In addition:

Red + cyan = white
Green + magenta = white
Blue + yellow = white

So cyan, yellow and magenta are complementary colors of red, blue and green respectively. Since everyone's eyes experience the same monochromatic color differently, if we mix the three primary colors with the same intensity, assuming that the intensity of white light is 100%, the subjective feeling of people at this time is that green light is the brightest, red light is the second, blue light is the weakest.

 

In addition to additive color mixing there is subtractive color mixing. Under white light, cyan pigments can absorb red and reflect cyan, yellow pigments absorb blue and reflect yellow, and magenta pigments absorb green and reflect magenta. That is:

White - red = cyan
White - green = magenta
White - blue = yellow

 

In addition, if two pigments, cyan and yellow, are mixed, under the irradiation of white light, the pigment absorbs red and blue, but reflects green, and the mixture of pigments is expressed as follows:

Pigment (Yellow + cyan)= white - red - blue = green
Pigment (magenta + cyan)= white - red - green = blue
Pigment (Yellow + magenta)= white - green - blue = red

 

The above are subtractive color mixing, subtractive color mixing is to absorb the three primary color proportion to form different colors. So the cyan, magenta, yellow called pigment three primary colors. The mixing of three primary colors of pigment has been widely used in painting and printing. Among the three primary colors of pigment, red, green and blue are called subtractive secondary colors or pigment secondary colors. In the subtractive secondary color are:

(Cyan + Yellow + magenta)= white - red - blue - green = black

 

The color mode represented by the above additive primary color mixing is called RGB mode, while the color mode represented by the subtractive primary color mixing principle is called CMYK mode, which is widely used in painting and printing fields.

 

RGB mode is the most commonly used color mode in graphics software. In this mode, it is more convenient to process images. Moreover, the image stored by RGB is smaller than that of CMYK, which can save memory and space.

 

CMYK mode is a pigment mode, so it belongs to print mode, but is essentially no different from RGB mode, except in the way colors are produced.

 

RGB is additive color mixing mode and CMYK is subtractive color mixing mode. For example, monitors work in RGB mode because they produce color by bombarding fluorescent materials on a screen with light from beams of electrons. It is black when there is no light and white when the light is at its maximum. And the printer? Its ink does not emit light of its own. Therefore, only colors that absorb certain light waves and reflect other light are used, so subtractive color method is needed to solve the problem.

 

(two), HLS(hue, brightness, saturation) principle

HLS are Hue, Luminance, Saturation. Hue is an attribute of color, it is essentially the basic color of color, that is, we often talk about red, orange, yellow, green, blue, purple seven, each represents a hue. Hue adjustment means changing its color.

 

Brightness is the brightness and shade of the graphic primary color of various colors (such as the primary color of an RGB image is R, G, B or a variety of hue), and brightness adjustment is the adjustment of brightness and shade. There are 256 levels of brightness ranging from 0 to 255. When we talk about grayscale images, we have 256 levels of brightness between pure white and pure black, which is white to gray and then black. Similarly, in RGB mode, it represents the brightness and shade of each primary color, namely the brightness and shade of red, green and blue primary colors, ranging from light to dark.

 

Saturation refers to the chroma of an image color. For each color, there is an artificial standard color. Saturation is a physical quantity that describes how close a color is to a standard color. Adjusting saturation is adjusting the color of the image. When the saturation bar of an image is zero, the image will become a gray image. You can try to adjust the saturation button on the TV.

 

Although printing can reproduce tens of thousands of colors, but because of the use of subtraction for color, the brightness of the colors will be weakened, and some bright colors are difficult to be expressed in print. On the other hand, the screen, due to the addition of color technology, in the range of color expression, is indeed richer than printing. This is why colors that look beautiful on screen cannot be reproduced in print, resulting in a difference in color between screen and print. The solution is either to improve the composition of ink and paper so that fresher, purer colors can be reproduced, but this does not happen overnight. Another approach is to narrow the gamut of the screen to fit the print, so that what the screen sees is what the print sees.

 

The gamut is the maximum range of colors that a device can record or reproduce. The color gamut of human eyes is all visible light, which is within the wavelength range of 380 to 780. The color gamut of printing is composed of paper and ink. Different paper and ink matching have different printing color gamut, and the color gamut of Pantone is different from that of book paper and DIC. Others, such as screens, scanners, printers, etc., also have their own gamut. It is practical to master the gamut of a device, because a device cannot record or copy colors outside the gamut. For example, normally, the human eye cannot see colors in infrared or X-ray light, and some colors that are easy for the human eye, like various metallic colors, are not easy to record in a scanner. The best we can do is to have the gamut of one device simulate the gamut of another. How to make the color gamut of the two devices seem similar to the human eye in the simulation process is an important theme of color production. [next]

 

Conduct color management and establish color standards

To produce color, it is necessary to establish a set of standards for the representation and transmission of color. Current popular color management systems such as LinoColor and Agfa's Phototone are developing in this direction. Through a set of standard specifications (ICC reference file) describing the color gamut of devices, color computing software is used to perform uniform color gamut conversion operations to reduce the color data transfer process. Color deviation and distortion due to color gamut and specifications. To implement these color management systems, the first step is to find out the color gamut characteristics of the device. The most commonly used method to describe the color gamur, is CIELab is the International Lighting Association, according to the visual characteristics of the human eye, the light wavelength into brightness and hue of a set of description color data, where L is to describe the brightness of the color, a represents the description of the degree of color red and green, b represents the description of the degree of color yellow and blue. In the CIELab color space, every color visible to human eyes has a position belonging to that color. By comparing the distance between the two color positions, we can determine the approximation degree of the two colors.

 

Since the visible light spectrum is the basis of this data, it can cover the colours produced by screens and printing, and can also be used to represent the gamut of the human eye.

 

For example, to describe the gamut of a printer, first print some test bars from the printer. These bars include major colors and colors that are difficult to reproduce. Then, the CIELab data on the bars are measured with a spectrometer. It also includes the production characteristics of the equipment, such as black plate characteristics, dot expansion, and so on. With the reference file of the devices, the color computing software can refer to the characteristic data of the two devices, and put the color gamut of the devices into the CIELab color space for comparison and conversion, so as to obtain a better simulation effect. This technology has reached the stage of production application, the most used is to simulate printing color gamut on the screen, and to simulate printing color gamut on the printer. Since the color gamut of the screen is larger than that of printing, the simulation in this case is also called gamut compression simulation. The whole simulation process is based on the data in the control file as the calculation basis, so the generation and management of the control file is the most important work.

 

Color management system assumptions

 

Is a color management system in place, that is, to produce the desired color results? To answer this question, you must understand the assumptions behind color management systems. The main job of the color management system is to simulate another known color gamut data on the CIELab space according to one known color gamut data. Therefore, it must be assumed that both color gamut data remain in the same state when the color gamut data is recorded. That is to say, the production state for establishing the equipment reference file must be the same as the production state for calculating the gamut. If the reference file established yesterday can not be compared with today's equipment, the production state is constantly floating, the color management system is not able to play a role in reducing the deviation. An unstable production process may even cause the color management system to amplify the color deviation. Therefore, the color management system is more suitable for the customers who have design, color separation, proofing and printing at the same time, because it is easier to control the variables of the production process in the same plant.

 

Color is not only an element of design, but also the production of receiving standards, even if the customer reluctantly accept a color unsatisfactory printing, the next may not patronize. Many companies lose important customers because of color quality problems. It can be seen that mastering the law of color presentation and controlling color quality is a technology that must be mastered in production. Only with advanced equipment without good technical cooperation, in the fierce industry competition, inevitable elimination of the fate.

 

Color principle

When it comes to painting and image, it is natural to talk about color. All patterns are composed of basic shapes and colors. Color forms an important part of our image processing.

 

(1) The principle of three primary colors

In the physics class of middle school, we may have done experiments with prisms. After passing through the prism, white light is decomposed into a spectrum of various colors gradually transitioned into red, orange, yellow, green, cyan, blue and purple, which is the visible spectrum. Among them, human eyes are the most sensitive to red, green and blue. Human eyes are like a three-color receiver system, and most colors can be synthesized by red, green and blue in different proportions. Most monochromatic light can also be broken down into red, green and blue. This is the most basic principle of colorimetry, namely the principle of three primary colors. The three primary colors are independent of each other, and no one primary color can be combined with the other two colors. Red, green and blue are the three primary colors, which combine the widest range of colors. The three primary colors red, green and blue are combined in different proportions to combine colors called additive colors.

 

Red + green = yellow
Green + blue = cyan
Red + blue = magenta
Red + green + blue = white

 

Yellow, cyan, magenta are made from the mixture of two and colors, so they are also called additive secondary colors. In addition:

Red + cyan = white
Green + magenta = white
Blue + yellow = white

 

So cyan, yellow and magenta are complementary colors of red, blue and green respectively. Since everyone's eyes experience the same monochromatic color differently, if we mix the three primary colors with the same intensity, assuming that the intensity of white light is 100%, the subjective feeling of people at this time is that green light is the brightest, red light is the second, blue light is the weakest.

 

In addition to additive color mixing there is subtractive color mixing. Under white light, cyan pigments can absorb red and reflect cyan, yellow pigments absorb blue and reflect yellow, and magenta pigments absorb green and reflect magenta. That is:

White - red = cyan
White - green = magenta
White - blue = yellow

 

In addition, if two pigments, cyan and yellow, are mixed, under the irradiation of white light, the pigment absorbs red and blue, but reflects green, and the mixture of pigments is expressed as follows:

Pigment (Yellow + cyan)= white - red - blue = green
Pigment (magenta + cyan)= white - red - green = blue
Pigment (Yellow + magenta)= white - green - blue = red

 

The above are subtractive color mixing, subtractive color mixing is to absorb the three primary color proportion to form different colors. So the cyan, magenta, yellow called pigment three primary colors. The mixing of three primary colors of pigment has been widely used in painting and printing. Among the three primary colors of pigment, red, green and blue are called subtractive secondary colors or pigment secondary colors. In the subtractive secondary color are:

(Cyan + Yellow + magenta)= white - red - blue - green = black

 

The color mode represented by the above additive primary color mixing is called RGB mode, while the color mode represented by the subtractive primary color mixing principle is called CMYK mode, which is widely used in painting and printing fields.

 

RGB mode is the most commonly used color mode in graphics software. In this mode, it is more convenient to process images. Moreover, the image stored by RGB is smaller than that of CMYK, which can save memory and space.

 

CMYK mode is a pigment mode, so it belongs to print mode, but is essentially no different from RGB mode, except in the way colors are produced. RGB is additive color mixing mode and CMYK is subtractive color mixing mode. For example, monitors work in RGB mode because they produce color by bombarding fluorescent materials on a screen with light from beams of electrons. It is black when there is no light and white when the light is at its maximum. And the printer? Its ink does not emit light of its own. Therefore, only colors that absorb certain light waves and reflect other light are used, so subtractive color method is needed to solve the problem.

 

(two), HLS(hue, brightness, saturation) principle

HLS are Hue, Luminance, Saturation. Hue is an attribute of color, it is essentially the basic color of color, that is, we often talk about red, orange, yellow, green, blue, purple seven, each represents a hue. Hue adjustment means changing its color.

 

Brightness is the brightness and shade of the graphic primary color of various colors (such as the primary color of an RGB image is R, G, B or a variety of hue), and brightness adjustment is the adjustment of brightness and shade. There are 256 levels of brightness ranging from 0 to 255. When we talk about grayscale images, we have 256 levels of brightness between pure white and pure black, which is white to gray and then black. Similarly, in RGB mode, it represents the brightness and shade of each primary color, namely the brightness and shade of red, green and blue primary colors, ranging from light to dark.

 

Saturation refers to the chroma of an image color. For each color, there is an artificial standard color. Saturation is a physical quantity that describes how close a color is to a standard color. Adjusting saturation is adjusting the color of the image. When the saturation bar of an image is zero, the image will become a gray image. You can try to adjust the saturation button on the TV.

 

Another concept is contrast. Contrast refers to the difference between different colors. The greater the contrast, the greater the difference between the two colors, and vice versa, the closer they are. For example, if a gray image increases its contrast, it will become more black and white. When adjusted to the limit, it will become black and white. Otherwise, we can get a gray canvas.

 

When we understand the principle of color, we are not at a loss in image processing, and we can adjust colors faster and more accurately. Another concept is contrast. Contrast refers to the difference between different colors. The greater the contrast, the greater the difference between the two colors, and vice versa, the closer they are. For example, if a gray image increases its contrast, it will become more black and white. When adjusted to the limit, it will become black and white. Otherwise, we can get a gray canvas.

 

When we understand the principle of color, we are not at a loss in image processing, and we can adjust colors faster and more accurately.