Compared with four-color printing, high fidelity printing improves the reproducibility and authenticity of printing colors by adding red, green, blue, orange and other color inks on the basis of C, m, y, K four-color printing.
High definition dot refers to the AM dot higher than 250 LPI, that is, 100% dot diameter is less than 125 μ M, and the equivalent diameter of 20 μ The frequency modulation dot below M. In order to improve the clarity of printed matter, printing with high-definition dot is called high-definition printing. High definition printing technology can effectively reduce the spacing of dots and improve the clarity and hierarchical performance of printed matter.
2. Color gamut
The main features of high fidelity printing technology include three aspects: first, in addition to black ink, C, m, y and other added color inks participate in color separation and neutral gray balance; Second, the printing color gradient change is closer to the real spectral color change effect than the four-color printing, and the printed matter has a strong sense of hierarchy and three-dimensional; Third, the printing gamut increases. Due to the limitation of ink materials and production technology, the spectral curve of ink is far from that of ideal color, and the printing gamut is small.
New color ink has been added to high fidelity printing. When users use high fidelity printing, they can adopt appropriate color adding scheme according to their own actual situation. Because different originals need to express different themes and different color emphases. For example, when printing strawberries, red and green are the key points of color expression, You can add red and green as the base colors. Different ink combinations are used to expand the gamut. For example, with C, m, y, K and R, G, B three color ink printing, the secondary color R, G, B can be vividly reproduced, and its gamut range has been significantly expanded.
High definition printing technology is to improve the clarity of printed matter as much as possible. The quality of printed matter mainly depends on the number of dots per unit area and the number of successive changes of dots from small to large. The more the number of dots per unit area, the higher the clarity of the printed matter, the more the number of dot changes, the better the level expression of the printed matter, and the better the quality and appearance of the printed matter. However, the printing gamut will not increase because the gamut is determined by the color of the primary ink. As long as the primary ink remains unchanged, the printing gamut will not change. At present, only high fidelity printing technology can really expand the color gamut of image printing, making the printing color brighter and closer to the real effect of nature.
3. Key technologies
The key technology of high fidelity printing is color separation, that is, how to correctly decompose the original color into different primary color components. At present, there are two commonly used color separation modes: one is to use the color conversion principle proposed by ICC, that is, to convert the original color into the printing color through iccprofile, and the actual method is to look up the table. Compared with four-color separation, high fidelity printing needs to divide the hue interval of color space reasonably, so that the input color of ink color matching has the minimum metamerism index, and the matching accuracy is improved. The second is to measure the tristimulus value of CMYK four colors and RGB inter colors, and calculate the printing color separation value, that is, the dot area ratio, by Neugebauer equation. It is a mathematical model. The goal of high fidelity color separation is to make the printing color as close as possible to the visual experience of the real scene.