In some printed products such as trademarks, certificates, packaging, etc., customers sometimes require a specific color that is overprinted with four colors of cyan, magenta, yellow, and black, or is often because of one of them. The amount of ink in the color changes so that the printed color also changes; or the target color cannot be printed at all. In this case, in order to ensure the stability of print quality and anti-counterfeiting requirements, customers often require the use of spot color printing. The so-called spot color printing is to print ink for a certain number of color inks according to a specific color specified by the customer and printed on the printing machine at one time. Because this kind of color is pre-modulated by the printing factory according to customer's target color, such as hue and brightness (whiteness), and it is printed on the spot, it does not have the jagged interference of the printing dots and the edges are neat. Color appearance is stable. The red color on the trademark of Beijing Red Star Erguotou Liquor is printed using spot color printing.
Obviously, the key to spot color printing is not printing but color matching. Today's color printing companies generally set up specialized personnel or departments to perform manual color matching. Artificial color matching is based on the visual inspection and experience of the workers. Some spot colors need to be deployed multiple times for a long time, which takes time and effort, greatly increasing the production cost, and are relatively backward color matching methods. At the same time, the use of ink brands, models, production batches, paper whiteness, color, printing pressure, speed, have an impact on the accuracy of spot color ink deployment.
With the continuous development of computer technology, in order to solve the above problems, computer color matching has gradually entered people's field of vision and received much attention. In the printing, printing, dyeing, painting, and coating industries, both domestic and foreign research and development institutions engage in computer color matching. However, the current computer printing ink color matching system is often based on a certain brand of ink, spent many years, the establishment of a basic ink database, the workload is large, the amount of capital investment is unimaginable. Therefore, its products are inevitably priced high, and companies have more stringent requirements in the selection of ink brands, virtually increasing the company's production costs.
In order to popularize computer color matching technology in the printing industry as soon as possible, aiming at the service of printing companies, with the aim of reducing production costs and improving work efficiency, China's printing science and technology research is based on the complex spectrum color theory of independent innovation, after many years of research. , Developed a simple and easy "CFS complex spectrum ink color matching system."
The modern color science theory was founded in the 19th century. By the 20th century, in the 20th century, a number of scientists selected red, green, and blue monochromatic light of different wavelengths for matching experiments, which proved that any natural light color can be matched with these three basic color lights. On this basis, the International Committee on Illumination (CIE) introduced in 1931 the “standard chromaticity observer XYZ tristimulus valueâ€, which laid the foundation for today’s CIE chromaticity theory.
The theory of complex spectrum chromaticity is based on the fluctuation and quantum of light. Based on the integral transformation formula of the neural signal, the wave equation of the electromagnetic wave, and Einstein's photon momentum formula, the pure physical concept of light to color is derived. Complex spectral color calculation formula. A detailed discussion of the theory of complex spectral chromaticity—“The analysis of complex color spectrum of physical color of light color transform†has been published in 2007 in the Journal of Beijing Institute of Graphic Arts.
According to the new complex color spectrum theory of light color conversion, the 3D color space of the CIE chromaticity theory is replaced by a 2D complex spectral chromaticity diagram, which provides the CIE xy chromaticity coordinates, dominant wavelength, color saturation, brightness, and Lab. At the same time, values ​​such as main frequency, hue, color intensity, and whiteness (color balance) are also given. The hue of the color corresponds to the frequency of the complex spectrum coating; the brightness of the color and the area surrounded by the sagittal curve of the complex spectrum, that is, the energy of the light; the color intensity of the color corresponds to the momentum of the photon; the color of the color The degree of balance corresponds to the white light content in the entire light quantity of the complex spectrum. The color of the complex spectrum is used to evaluate the color, neither the tristimulus values ​​of the CIE nor the red, green and blue color filters. The complex spectrum color measurement method is physical, and the evaluation is objective, which is conducive to the establishment of a completely objective physical color evaluation system.
The natural world is full of colorful colors, and color matching is to use just a few or even more than a dozen colors as the basic colors and use them to match each other to modulate a specific color. However, since the printing ink is a reflection color, any color cannot be used as the basic color. The conditions suitable for basic colors are: 1 color gamut should be broad, reflectivity should be high; 2 hues adjacent to the two basic colors should have a wider common response frequency domain; 3 should have higher color intensity in its The lower the complementary color domain reflectivity, the better; 4 in the complex spectrum of red, green, blue and blue color areas to be a reasonable distribution. The two adjacent basic colors are neither too close nor too far apart.
Theoretical innovation will inevitably bring about technological advancement. The CFS complex spectrum ink color matching system has a powerful, fast, ink-compatible printing ink color matching engine. It is based on the basic color ink database established independently by the company. Through the measurement of the target color, combined with the price and inventory of the basic color ink of the company, it uses “fast color matchingâ€, “precise color matching†and “strict color matching†This kind of color matching method provides multiple color matching schemes such as “optimal hue†and “lowest costâ€, which enables companies to get rid of complicated and expensive trials and trials, which greatly reduces the company’s production costs. CFS complex spectrum ink color matching system features:
• Independency with the ink brand - Based on the new theory, the use of scientific calculation methods, make the color matching system as much as possible to adapt to the company's commonly used printing ink.
• Reduce printing production costs - With accurate and fast color matching engines, companies get relief from the complex and expensive trial and error.
• Newly added color difference content - In addition to providing ΔE, there is a more specific chromatic aberration difference ΔH, luminance difference ΔL, and color saturation difference ΔS.
• Unique color correction scheme - Based on the measured and calculated color difference parameters, it provides an operational color correction scheme.
The advantages of computer color matching are economical, rapid, and accurate, which cannot be compared with artificial color matching. The CFS complex spectrum ink color matching system researched and developed by the China Institute of Printing Science and Technology, the theory is independent innovation; the calculation method has obtained the national invention patent, is accurate and reliable; the operation method is in line with the Chinese users' habits; the price is reasonable.