Papers by Keyword: Moiré

Abstract: Moire, an abnormal printing pattern formed by irregular screen tone, may adversely affect the printing quality and should be avoided during printing. Hence, it is necessary to understand the factors contributing to its formation. Being one of the most important factors, the effect of screen angle is discussed in this paper. To obtain the most suitable screen angle and confirm its rationality, Photoshop is used to simulate Moire patterns under different screen angle conditions and analyze the relationship between screen angles and formation of Moire pattern. When mixing two of Cyan, Magenta, Yellow, and Black colors randomly while keeping the others constant, the size of the Moire is not affected by screen angles but by the angle differences. When the difference is at 28° and 38°, Moire pattern is not obvious and the dots are evenly distributed. The screen angle difference and the screen angle of the key color are also analyzed from the Moire pattern obtained by varying screen angle between C, M, and K (Black) in the simulation study. The results show that it is reasonable to set screen angle for strong color at 15°, 45° and 75°.

Abstract: Image halftoning is the core technique of digital image output, which determines the quality of the color and tonal gradation reproduction. In this paper, the existing halftoning techniques were analyzed and evaluated, such as FM halftoning and AM halftoning, etc. And a new halftoning mode, frequency conversion amplitude modulation (FCAM), was proposed. This method is still based on AM halftoning, but it uses the different screen frequency for halftoning image of the different color version, so as to avoid moiré fringes on the smaller superposition angle. The use of new halftoning model can achieve halftoning image output which is more than 4 colors (such as 6 colors or 7 colors) without visual moirè pattern when overprinting. By the new technique, high-fidelity printing is achieved, and the color gamut of the output image is expanded, and we can get more vivid realistic effect of image transmission. We tested color gamut expansion of 6 colors and 7 colors high-fidelity printing, and obtained the expected conclusion by quantitative analysis.

Abstract: Mathematical model for moiré in screened two-color overprinting process was established, and the formation rules in multicolor overprinting processes were investigated by computer simulating experiments. Results showed that the formation of moiré depends on the screen rulings of color separations and the screen angles at which color separations were positioned to each other. The visible moiré patterns would severely interfere the structure of printing images, however, it was impossible to entirely avoid these visual disturbances, and good measurements should be taken to control the moiré effects. Optimal solutions for multicolor overprinting processes and effective measurements for special originals were put forward to reduce the interference effects of moiré. The results of this paper can help for improving the printing quality and promoting the anti-counterfeiting technology using Moiré.

Abstract: Based on the principle of moiré techniques, a new method combined with Electric Addressing SLM technique was proposed. The specimen grating is modulated by the SLM system, and its the frequency can be changed with aid of a 4f Fourier system. The moiré is generated by the overlapped specimen grating and a reference grating in the Fourier system. Typical test is conducted with a polyurethane beam. The successful results verify the feasibility of the method, and show its good potential of further application to the in-plane deformation measurement.

Abstract: In this paper, a new technique for fabricating grating on the surface of porous TiNi SMA is proposed. The grating is directly written onto the surface of the specimen using the FIB milling. No photoresist is required during the lithography process. From the experimental results, it can be obviously seen that the grating fabricated by FIB milling has a better quality than that by electron beam lithography. Using the self-made FIB grating, the in-plane deformation of the porous TiNi SMA in microscale is studied by SEM moiré method. Moiré and the microscopical structures are synchronously observed, including microcracks, martensites and grain boundaries.