General Discussion on Color and Color Management (in)

3.0 Color Spaces
The color space is a mode in which the color value is represented by an intensity value. The color space specifies how the color information is expressed. The meaning is that the intensity value is expressed in one, two, three, or four degrees space or a combination, and viewed from the outside, often in various solid states. Shapes such as cubes, cones, or polymorphs represent these spaces.
Commonly used color management software supports several different color spaces to give users ease of operation, and most of them are suitable for any kind of color data needs.
The color space of the commonly used color management software belongs to several groups or basic color families. The additional color space and high-facsimile color space are mainly used for gold and silver and color printing jobs.
3.1 Gray Spaces
The gray space typically has only a single component, ranging from white to black, and grey spaces are used for the display and printing of black and white and grey series.
If expressed as 100%, 0% is white and 100% is black. From 1 to 99 are all gray, but the degree is different. The smaller the number is, the closer to white-gray, the larger the number is, the closer to dark gray.
3.2 RGB-based Color Spaces
The RGB-based color space is mainly the additive third-degree color space. Different intensity red, green, and blue light intensities can be used to form a variety of colors. For example, a scanner reads certain portions from the image. The red, green, and blue light reflect the amount of light, and then convert this amount of light into data. After the monitor receives the data and then converts it into the specified components of red, green, and blue light, since the pixels are small and close together, The eyes inside us make us mistaken for seeing many different colors.
The RGB-based color space is the most commonly used color space in computer graphics, mainly because most color displays directly support, but the colors generated in the RGB format will vary between different devices, so called "devices The "owned color space" means that the device's color space is only allowed to be directly associated with the format of the color value they describe on a particular device.
The color space groups within the RGB base color family include RGB space, HSV space, and HLS space. RGB space means that any color expressed in RGB space is some mixture of the three main colors red, green, and blue. The HSV and HLS spaces are terms derived from RGB space for narrative color. HSV stands for hue, saturation, and brightness. HLS stands for hue, brightness, and saturation. These are quite common and familiar in color. noun.
3.3 CMY-based Color Spaces
With CMY representing the three main colors of cyan, magenta, and yellow, the color space based on color is most often used in color printing systems. The nature of the color space is a subtractive method relative to RGB, which is also the color space to which the device belongs.
CMYK uses black instead of CMY. The printing method uses four-color inks or dyes on paper. The two colors in the same ratio can be mixed to produce "secondary colors," such as red, green, and blue.
CMYK color is different because of the characteristics of the printing machine, ink, and paper. In addition, the color gamut produced by different devices is also different because the colors produced by RGB and CMYK formats are also different between devices and devices. Differences, so the device belongs to the color space. There are also many variables when converting the RGB color space to the CMYK color space, which relates to the device size, ink type, and even the paper characteristics to calculate the total amount of black ink added in the dark portion and shift the other color ink in the black ink portion. Excluding the total amount.
Color management software accomplishes these calculations when making color space conversions.
3.4 Device-independent color Spaces
The device-independent color space is mainly used for color modules and for conversion between RGB and CMYK modules beside the system.
Each color monitor has its own color gamut even though it was manufactured by the same manufacturer in the same year and because of different RGB phosphors. The same applies to printers and CMYK toners. This is usually more than most displays. Many color gamut limitations, because the color produced by the two different formats of RGB and CMYK will be different due to the difference between the device and the device. This is the characteristic of the color space to which the device belongs.
Some color spaces allow colors to be expressed in a device-independent manner. The color does not depend on any particular device, but instead is a true color representation perceived by the human eye. These color representations are called device-independent color spaces and were developed in 1931 by the International Standards Committee (CIE) and are therefore called CIE-based color spaces.
The goal of CIE is to establish a standard system of repeatable color communication for paint, ink, dye, and other pigment manufacturers. The most important function of these standards is to provide the overall structure of color matching. Device independent color space is used for color data conversion from one device-specific color space to another device-specific color space, and those representing the entire visible color range are conversion spaces. This means that any color selected on the display is the color gamut of this neutral color space.
CIE L*a*b* is a three-degree color space based on human color sense. It is the most widely used color space of CIE. The L*a*b* color space is based on the fact that one color cannot be green and red at the same time, nor can it be The theory is blue and yellow, and as a result, a single shade can be used to describe the red/green and yellow/blue properties.
The CIE L*a*b* space represents the color associated with the reference white point, which is the specific meaning of white light, and is usually based on the white light the device can produce.
The CIE color space constitutes an independent color base for devices used for color management.
4.0 Color Reproduction
Although there are only two basic methods that can be used to reproduce colors, there are only two basic methods—additive and subtractive methods (please refer to 2.4.). Both are generically called three-color methods and are based on different principles of three primary colors to create full-color. .
Understanding these two systems will understand the principle of many color reproduction operations in printing. It is the basis for understanding the tone reproduction, gray balance, and color correction of halftone color reproduction, and obtaining proper contrast, color balance, and hue. It's decisive.
4.1 Color Printing
Printing is based on the subtractive method and is usually printed on white, near white paper, or any other white object. Since the surface of the "white" paper reflects all the light waves in equal amounts, white appears. When the color is reproduced, we It will intuitively assume that the color is in the paper. In fact, after printing on the surface of the paper with clear inks (cyan, magenta, and yellow), the red, green, and blue light waves are filtered out after multiple bonds, and the paper itself does not change color.
Considering the transparent four-color inks, such as the red, green, and blue wavelengths we see in our eyes, rather than those that are combined on paper to reproduce the colors, we have found that by combining the two ink light waves and subtracting the other ink light wave.
Theoretically, combining all three color inks can avoid all reflected light waves and produce black color. Even the best four color inks will not uniformly absorb light waves. When combined with cyan, magenta and yellow ink, the combined three-color ink absorbs. The wavelengths are not uniform and the red part of the spectrum reflects more. The result is a brownish tone rather than black. In order to make up for this disadvantage in printing, black ink is used in the color printing process.
Paper has a significant effect on color reproductions. Paper reflects non-absorbed light waves to the viewer, and coated paper has a strong reflective surface that produces a wider color range than uncoated paper. Rough non-coated paper The surface will spread the light, reducing the amount of reflection on the viewer, and therefore feel darker.
4.2 Pursuit of Correct Color Reproduction
The issue that has been explored since the previous color reproduction. Prior to the 1970s, most color separations were performed with red, green, and blue color filters in front of a plate-making camera or magnifying lens. Skilled technicians obtained a good color reproduction by their own experience. From the manuscript, multiple procedures are used to create color correction films, color separation films, and mesh, and then the dots are etched to obtain the desired halftone mesh. Later, some manufacturers used the contact exposure method to change the size of outlets. With many adjustments, it took a long time, but it may not be able to obtain the desired color.
After the 1970s, it was the era of high-order electronic or laser scanners using numerous knobs and buttons for color adjustment. Although these expensive analog scanners lack computer memory and digital devices to store images, later models convert the RGB digital color signals to CMYK color separations by the computer, the original is mounted on a transparent cylinder, and the other cylinder is The dichroic film is installed. The scanner is calibrated by experts who are trained in advanced technology and make the best input and output settings. However, re-sweeping is still quite common. Especially for prints with special colors, if the colors do not match, the adjustment of the scanner or the knowledge of the operator is usually not a limiting factor, but is affected by the quality of ink and paper.
With the addition of sophisticated color controls on the scanner, or prepress, printing or post-press, from the use of the naked eye to color control via several densitometers, tube charts, ink and paper tests, printing has been transferred from the process Into science and technology.
In the 1980s, advances in minicomputers, memory, and storage devices enabled color electronic prepress systems (CEPS) for storage, display, color correction, and image matching. For example, Scitex Response and Hell Chromacom's multi-million-thousand-million-dollar system can obtain high-quality color reproductions, but it also takes a long learning time.
In the 1990s, a powerful desktop prepress system appeared. Innovative page description output (postscript), image platforms such as Apple, Microsoft, and publishing software such as Adobe Photoshop, Quark Xpress can use desktop hardware to make high-end color quality, and its ease of use, low-cost combination system quickly replaced Expensive stand-alone system.
Scanning and color separation, once the need for highly trained experts, became popular, anyone including photographers, designers, typeetters, and computer operators could operate a computer, scanner, and printer to accomplish separation. Full operation. Desktop computers use open systems and theoretically support unlimited color computer peripheral devices. Today, many of these color publishing products are able to consistently operate, but they still have to face the same problems and how to make accurate colors.
5.0 Color Management
Even if today's electronic publishing is cheaper and easier to use than the previous system, the high quality of color reproduction still requires rigorous training. Color is a complicated subject, perhaps more than we use computers to reproduce. complex.
Color management can save time and money by reducing the total number of hours and the amount of material for color users when completing color production tasks. It allows the user to match colors on different input and output devices, to see in advance what color cannot be accurately reproduced on a specific device, and to simulate the device's color range on another device to achieve accurate, repeatable color Replication involves the use of software and hardware to calibrate and use data curves to represent input and output devices.
Color management is the writing of color expertise and science into software that attempts to simplify color reproduction. For example, desktop computers have been significantly changed and published, and color adjustments have been automated to make it easy, reliable, and rapid for users with low or inexperienced technology. Finish color reproduction.
5.1 Brief History of Development (Grief History)
At the end of the 1980s, several application software developed by several companies that led color technology to solve the problem of mismatched color between devices in a color table publishing system was commonly referred to as a color management system or CMS.
However, early color management systems were not widely adopted. One of the basic problems is that each device uses a different architecture. In order to implement the color matching function, the application manufacturer must create some specific requirements for it because there is no universal color management architecture. Can be used, each application itself must cooperate with the hardware supplier, of course, the new and improved CMS has been introduced, but there is no consistent compatibility between the source file and the results.
Apple Computer