The digitization of the commercial printing process has resulted in greater utilization of the inkjet digital press method in numerous fields. Image processing tasks commonly performed with the inkjet digital press method include resolution conversion, color conversion, total ink amount limitation, gradation conversion, and halftone processing. For this method, halftone processing has the most significant influence on image quality. Because of favorable dot reproduction characteristics, the dot dispersed-type halftone is utilized in the inkjet digital press. The error diffusion method or organized dither method is employed for dispersed dot reproduction. To obtain high quality halftone processing, parameter optimization is essential. Currently, parameter optimization is accomplished via a simulation technique that predicts ink dot reproduction on the output media. In addition, an evaluation function that considers human visual characteristics is included in the optimization process. For single pass inkjet printers, the most suitable dot placement is selected to minimize banding and streaks.

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In Japan, the utilization of the Print Inspection System for sheet-fed offset presses has increased in recent years. As a result, the printing industry has become standardized, thus increasing the necessity for printers to differentiate their quality control from their competitors. Correspondingly, the print inspection system should be considered as a comprehensive, holistic system, which not only checks defect sheets but also improves printing quality, utilizing feedback inspection results from previous processes. Additionally, the system must improve the factory environment and reduce printing material waste.

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We have developed image processing technologies for the creation and distribution of digital comics (e-comic). In this paper, we introduce image processing technologies for digital comics, such as moiré-less image resizing, highly efficient comic image compression, automatic speech balloon detection, and GT-Translate, an automatic digital comic translation technology.

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Digital archiving of historical documents is an important effort in Japanese historical research. Digital images are becoming the core contents of the historical archives. To record large numbers of documents efficiently, and to promote the utilization of the archives, numerous researchers have high expectations of information technologies. Because digital archives of these documents are accessible online, they can be observed from anywhere. In addition, by accessing the digital archives instead of the original documents, the original documents can be maintained in safe repositories. However, the qualitative expression of the original documents is frequently superlative to the digital copy. To improve the historical value of digital archives, it is necessary to carefully consider all archiving processes, including digital image photography and meta-information definitions. Furthermore, the large volume of contents from the archives must be managed effectively. In this article, I begin by presenting the subjects and the significance of digital-archiving, which processes and preserves historical document information. Subsequently, I present two examples of information storing in digital archives at The Historiographical Institute, The University of Tokyo, and the Nara National Research Institute for Cultural Properties. To conclude, I introduce several information technologies to extend the utility of the digital archives.

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As one of the most significant substrates in printing, the spectral reflectance of blank paper imparts a decisive influence on the color of prints. To understand the interactions between the incident light and blank paper, a spectral reflectance model involving a single sheet of blank paper was established in this study. When determining the factors affecting the reflectance of paper, the model considers the effect of the background as well as the non-optical contact between the paper and the background. A number of initiatives were employed in this research. First, a single sheet of blank paper is abstracted as a multilayer structure comprised of five different parallel layers stacked over each other. Second, in this proposed model, four non-measurable optical parameters, namely the internal reflectance of the paper-air interface, the external reflectance of the paper-air interface, the intrinsic reflectance of the paper layer, and the intrinsic transmittance of the paper layer, are determined by adopting the nonlinear regression method for the measurement of the spectral reflectance of paper samples placed on different opaque backgrounds. Finally, the accuracy of the proposed model was verified by comparing the predicted and the measured spectral reflectance of the same paper samples on other opaque backgrounds. Throughout the experiment, seven different types of printing papers were selected, which include coated paper, newspaper, and matte paper from China, and coated paper and washi paper from Japan. The results of the experiment proved that the proposed model generates accurate predictions, as compared to the measurements describing the color rendering for a single sheet of blank paper.

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