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HD-Flexo printing is the flexo printing technology with 150 LPI and above, which is the key and difficult research in recent years. This paper studied the present half toning algorithms of HD-Flexo and image segmentation algorithm. The Region Growth and Segmentation Algorithm (RGSA) is proposed by theoretical derivation and experiment. The algorithm implements meticulous segmentation of different gray areas of the image (minimum gray scale 0.39%), and effectively reduce the boundary effect of the segmentation region in the segmentation process, which is conducive to the hybrid halftone to form a smooth result.

Equipment calibration is the premise of equipment characterization and acceptable printing quality in printing workflow. The calibration and characterization of displays are often based on two basic assumptions—channel independence and chromaticity constancy, according to which many modified models are proposed. However, there is no research progress in the theoretical basis of printing output equipment calibration. Although the calibration of output equipment is one of the routines in the printing workflow, there is no discussion about why the output equipment can be calibrated. According to chromaticity constancy of the display, we deduces the relevant formula and conclusions of chromaticity constancy in printing output equipment. This paper builds the theoretical basis of output equipment calibration and helps researchers to study further and improve the output device reproduction performance on the base of our basic theory.

In order to accurately reproduce the yellow color of old books on monitor, in this paper we collected the color value of old books and prepared a color card whose color gamut is narrow but can include the color of old books. Then we made a display ICC profile according to the traditional color management steps, and measured the color value of old books displayed on the monitor which was embedded the narrow gamut ICC profile. Statistics indicate that the color value of old books displayed on the monitor embedded the narrow gamut ICC profile is closer to the color value of real old books. Compared with the traditional color management that the color value of old books is displayed on the monitor embedded the common ICC profile, it shows that our color management process based on small color gamut can achieve a perfect effect to the yellow reproduction of the old books on monitor.

Objective: with the premise of printability of graphene ink, the printing technologies with graphene ink are applied in a large scale for printed electronic products, realizing the extensive application of intelligent packaging. Methods: in conjunction with characteristics of graphene ink, this article adopts top-down and bottom-up preparation techniques and produces auxiliary dispersant by using n-methylpyrrolidone (NMP), dimethylformamide (DMF), polyvinylpyrrolidone (PVP), and surfactants for observing the changes of printability of graphene ink. Results: a technological breakthrough has been made in graphic technologies, such as screen printing, gravure printing, flexography, lithography, inkjet printing, and plate making methods in the applications of graphene inks, especially empirical research on micro-contact printing based on flexography has been verified. Conclusion: the discovery of graphene significantly promoted the development of flexible electronics. Green and sustainable graphene ink with excellent conductivity can replace traditional metal components in electronics industry, with promising prospect.

Color gamut mapping technology includes two parts: color gamut boundary description and specific mapping algorithm. To improve the accuracy of mapping calculation, so far, there have been hundreds of specific mapping algorithm has been proposed, but most of these algorithm is mapped from device to device, but the algorithm from image to device is relatively lack. The error can’t be eliminated when image color gamut boundary is descripted by the existing algorithms, and calculation efficiency is low. This paper present a precise, fast, and zero error methods to extract image color gamut boundary (we call it IGBAD), combining IGBAD method, fast color gamut mapping method is put forward. The redundant calculation is eliminated in the process of mapping; the efficiency of map calculation is high.

Under the different experimental condition, different combinations of halftone samples were printed out with UV flexopress. More than 100 groups from different substrates, print speed and photoinitiator of reflectance spectra of the samples were measured. The morphological character indices (spectral area, perimeter, depth, width of shoulder) are selected and the variations of sample of different printing conditions are analyzed. The conclusions are that, the correlation between these morphological indexes was obvious; 4 chosen morphological indices were removed, whose R2 was greater than 0.9 (R is correlation coefficient) and confidence level was greater than 0.05, the best morphological index was chosen for different character wavelength of different primary color; the variation of different morphological indices in different wavelength was distinct; the relationship between morphological character and the printing conditions was fitted by linear and polynomial curves, R2 is greater than 0.9.

The paper studied about the characteristics of ink sludge of flexo printing and analyzed the possibility different reduction treatment and disposal. Industrial analysis and elemental analysis to confirm the elemental content, TGA and DTG were used to analyze the weight loss and heat absorption and desorption behavior of dry sludge at different temperature. GC-MS and XRF analysis was applied to analysis the composition and content of the compounds. Three kinds treatment for for ink sludge based on different needs.

The paper proposed a new gamut mapping algorithm based on General Regression Neural Network (GRNN) for the problem that the color of pictures can’t be reproduced perfectly in the cross media transmission. The two groups color samples were created by Matlab. One color group is Adobe RGB as the original gamut, and the other is sRGB as the aim gamut. Then they were converted into a Profile Connection Space (PCS), such as CIE LAB or IPT. The GRNN gamut mapping module, the mapping relationship of the original gamut and reproduction gamut, were calculated with color samples. The color differences of mapping and original pictures are small in general and the saturation of mapping picture is higher than that of original picture. The different PCS has effect on the mapping result of specific type picture. The gamut mapping result of GRNNGM (General Regression Neural Network Gamut Mapping) algorithm is better than the HPMINDE (Hue Perceived Minimum Color Difference Error) algorithm. Lab space is more fit with the face picture mapping and there are no significant differences to the other types of pictures.

To study the performance of the three spectrophotometers: Spectroeye, i1, and eXact, the spectral reflectance of X-rite ColorChecker® was measured with them. By computing the standard deviation of spectral reflectance and color difference \( \Delta E_{ab}^{*} \), the stability and repeatability characteristics of the three color measuring instruments were analyzed. The results showed that the standard deviations of spectral reflectance are less than 0.001. The average color difference between the measurements and reference data is less than \( {2\varDelta }E_{ab}^{*} \). The color difference between each two spectrophotometers is about \( {1\varDelta }E_{ab}^{*} \). The measurement error between the spectrophotometer is acceptable, so we could choose corresponding instrument according to the range of measurement wavelength.