A lossless coding of an error-diffused image by coding a multi-level image generated through inverse halftoning process using soft decision method is proposed and studied. In order to study a coding method of error-diffused image in the domain of multi-level, it is necessary to find the image having minimum entropy, so far as it can produce exactly same error-diffused image at the receiver. To find such a multi-level image, we applied the idea of Viterbi decoding in inverse error diffusion process. The result shows that the multi-level image derived by proposed method has about 10-19% less entropy than the bi-level halftone image and 27-49% less entropy than that of the original multi-level image, which means that the multi-level image coding could be a good method for coding error-diffused image.
Recently, an infringement of copyright by illegal copy of digital contents becomes a problem. Digital watermark technology is a solution of this problem. Watermarking Methods are classified into two types. One is a reversible watermarking method which can restore to the original image from a watermarked one, and another is an irreversible watermarking method. However, an irreversible watermarking method cannot be utilized to some sort of application system such as a medical imaging system. Therefore, we propose a reversible watermarking method. In the proposed method, two wavelet coefficients in several bands are treated as a vector, and one bit of a watermark is embedded into the vector. The reversible restoration can be performed by keeping one-to-one relationship between the original vector and the converted one. Simulation results show that the proposed method has better performance than the prior study using wavelet coefficients.
Dither methods are generally used for representing multi-level images to a bi-level display, and various techniques of dither methods have been proposed. Especially, the minimized average error method is known as one of the excellent methods in the image quality. However, in this method, it is difficult to get a high compression performance. In the preceding studies, we proposed a data compression method of minimized average error images using the Schalkwijk code. First of all, the dithered image is divided into some blocks in this method. Secondly, the Shaclkwijk code is applied to each divided block. In the preceding work, we used only 4*4 pixel size for dividing into the blocks. In this paper, we consider the various block sizes such as 3*1, 2*2, and 3*3. In this paper, we consider various block sizes to divide the image, and we report simulation results of compression ratio.
We conducted a protocol analysis experiment to examine the usability of electronic books for the aged. Elderly people and college students took part in the experiment. The experiment revealed similarities and differences between the aged and young readers when reading e-books. For the elderly, the ability to change the size of printed words of e-books is particularly useful. We conclude that e-books are not necessarily easy to use for either the elderly or young readers, and that greater efforts are needed to improve their user-friendliness.
To develop electrophoretic display more, manufacturing technologies are important. Up to now, the technique named Encapsulation and Roll-to-Roll Manufacturing processes has been introduced. It is considered that the technique is carried out from the view point of simplification of manufacturing method. In this report, an attempt to realize very simplified manufacturing technique is introduced.
An electrophoretic display (EPID) based on the movement of particles in an insulating liquid is well known to be one of the technology utilized for the electric paper and has been actively investigated in the past few years. Emulsification and micro-encapsulation of dispersion containing with white and black particles dispersed in an insulating liquid is reported in this paper. The gelatin and melamine resin was used for surfactant and wall material of micro-capsule, respectively. The optimization of the preparation condition of the micro-encapsulation was done. The EPID using the micro-encapsulated electrophoretic ink displays black and white solid image in the response to an external voltage.
We provide an overview of the technical trends in E Ink Electronic Paper Technology through recent and development and commercialization activities. The initial product launched in Japan in 2004 was for Electronic Publishing applications, but since then, large-format public signage, watch/clock applications and other novel applications have appeared and Electronic Publishing applications are spreading to Chinese, European and U.S. markets. On the technology side, advances in response time and the development of Color E Ink displays make it a prime candidate for the reflective display of choice in the era of ubiquitous computing.
In this article, it is explained the new IEC61966-2-4 xvYCC standard that is established recently and which defines Extended gamut YCC colour space for video applications. At first, various color standards which have wider color space are explained. Secondly, a conversion method of a color signal which is based on a xvYCC standard is explained. Finally, the color gamut between conventional standard and xvYCC standard are compared.
We have been developing wide gamut LCD monitors which are applicable for the printing industry, and have succeeded to produce wide gamut LCD monitors using 3 or 6 color LEDs as the light source for backlighting. This paper describes the features and color reproducibility of these prototypes.
We propose a color conversion method for displays that reduces color reproduction error caused by device drift, imperfect color additivity and color tracking. A correction matrix extracted by multiple regression is applied to temporal chromaticity change of primaries. A gamma correction is adopted to time cource of tone reproduction curves. A correction matrix obtained by the Quasi-Newton Method is applied to imperfect color additivity. Furthermore, the OCT method, that has been proposed by three of authors, is used for reducing effects of color tracking phenomenon. As a result of reproducing colors, the methods respectively corrected errors induced by three phenomenon. Finally, these methods were optimally integrated and reduced an average of 60% color difference for two displays.