고품질 색재현을 위한 오프셋인쇄 공정의 최적화에 관한 연구

Abstract

For the color offset printing, it starts with input of data. The past days, drum scanner or flat scanner used to input of data, but now it changes gradually into using of digital camera because digital camera become popular. The high quality digital camera saves things as a data(RAW file format), sRGB which have built in digital camera, or Adobe RGB format. sRGB of ICC(International Color Consortium) profile is a standard color gamut of digital camera. In ICC profile, Distribution of color gamut in sRGB is less distributed than Adobe RGB. sRGB also can not be expressed in some specific part, because distribution of color gamut in sＲＧＢ is not able to cover all parts in ICC Profile of international standards CMYK. By these reasons, it is more popular to use Adobe RGB than sRGB to do high quality offset printing and software basis color setting in Europe and Japan. In spite of this data basis, there is a difficulty of doing color correction between the color proofing prints and the final prints. Producing printing plate is essential progress to do offset printing. In this Film-less period, the more PS plate becomes extinct, the more the age of the Plate-Making of Exposure declines the place to stand. To do offset printing, the CTP (Computer to Plate) is taking a place of PS plate that covers speed, quality and economical problems. The biggest advantage of using CTP is that laser directly goes to the plate, thus there are no dust from the Plate-Making of Exposure. It is also theoretically able to print 200lpi～300lpi as well as print 175lpi, because it has over 2400dpi resolution. The high quality printing could be available inside of the country, if printing machine keeps the optimum condition in offset printing. The CTP has many advantages, however there is a difficulty for the operators to preserve the equipment. The actual circumstance is that they cannot make a decision about how many dots need to be generated, and also it is necessary to know how to establish the setup at RIP on CTP to make the optimum condition output. If offset printing machine keeps the optimum condition, it would be able to print up to high quality printing however it is hard to comment what is the optimum condition for the printing machine. In a subjectively view, anyone could easily say that machine is in the optimum condition, however it is hard to estimate by number objectively. To see how the software color setting effects to RGB data, this thesis will use GretagMacbeth ColorChecker 24 patch which has the most general natural color chart to compare sRGB and Adobe RGB to check the differences of color changes. It will use the several factors that came out from the process of making ICC Profile to figure out the optimum In-house profile. It also compares the differences of using matt paper and glossy paper to do best quality color proof offset printing, and how the Rendering Intent effects the proof print. Also in this research, GATF / Plate Test target used to analyze the image and to make numerical value of the optimum condition of the CTP. It also uses GATF / The sheet fed test printing 5.0 to find the best establishment of printing density, dot gain and gray balance for the optimum condition of the print machine. The purpose of this research is to represent the ISO 12647-2 : 2004 / Amd1 : 2007 with domestic printing system which does not have standard of offset color printing. Therefore this thesis tries to find optimum condition of a domestic offset printing process and it expects the development of the domestic high quality color offset printing.