Many digital hardcopy output systems are challenging to enter into the photo-finishing market. This market is based on human desire to record people’s visual experiences in the form of photographic print. The present paper discusses main features of this market. First, three factors supporting this market are mentioned, i.e., the human credit to information transmitted by light, people’s intuitive recognition that photographs are the genuine work of light, and the strongly personal or subjective value of photographs. Then, the sources of the aura photographic prints uniquely assume are discussed to derive two factors, i.e., their smooth highlight description and surface structure reminding water surface as the most significant. Finally, essential conditions digital hardcopies for photo-finishing market must satisfy are described in relation to some empirically found aura quenchers.
Communicating color gamut is very important in color research and application. The problem of calculating image gamut, however, has no definitive solution yet. In this paper, we introduce that an entire gamut volume can be calculated by tetrahedral color values listed in known orders. The corresponding color gamuts are analyzed and compared. However, the orders of color values in a given image are unknown at first. We propose a new method for calculating the gamut volume by rearranging the color values. The entire color space is firstly divided by hue angle ΔHab and secondly by lightness ΔL* where the steps (ΔHab, ΔL*) are decided in non-uniform to include the constant color samples in each segmented sectors. Finally the most out-side points from the center are extracted and the entire gamut volume is calculated by summing up the individual volume of tetrahedral with selected color values. This method is available to describe the surface of image color gamut.
We have studied a new metric for color image noise (graininess) evaluation that is also applied to monochrome images. Graininess would be the most important and basic attributes for pictorial images, and Graininess Scale (GS) has been widely used as a noise perception model. Similar to the treatment adopted in the GS, we have computed Lightness Noise (LN) by using the lightness instead of the reflection density and by using a new sensitivity function based on a model describing our observations. But LN would not be sufficient for chromatic images as it is. So, we focused our attention on the fluctuations of both chroma and hue-angle on color images as these decrease perceived color image quality. Chromatic Noise (CN) has computed by using these fluctuations with consideration to spatial filters by the human visual system. Finally, we have obtained Graininess Index (GI) by using both LN and CN. To confirm our approach, we made subjective assessments for test patches, and got good relationship (γ=0.91) between GI and subjective evaluated levels.
Indigo is composed of two pairs of NH group (electron donor) and C=O group (acceptor) which form strong intermolecular hydrogen bonds based on NH…O. Quinacridone (QA) and diketopyrrolopyrrole (DPP) are also classified into the same kinds of hydrogen-bonded pigments. While the color of QA and DPP in solution is pale-yellow, indigo exhibits a vivid blue color in solution. However, crystallization of QA and DPP induces a large bathochromic shift (about 1,500-1,600cm-1) to give a brilliant red color in the solid state, whereas the spectral shift in indigo amounts only to about 1,100cm-1. This mechanism has been tackled from the standpoint of molecular and crystal structures as well as intermolecular interactions. The transition dipole of indigo is found to point the long-molecular axis, while it is along the short-molecular axis in QA and DPP. Therefore, in indigo, the electrons can well be delocalized upon photo-excitation along the long-molecular axis, leading to an optical absorption in the visible region (“blue color”). On the other hand, the electron delocalization is limited only along the short-molecular axis in QA and DPP,giving a pale-yellowish color. In the solid-state, the interaction between transition dipoles is found to play an important role. The intermolecular hydrogen bonds in QA and DPP align the transition dipoles (“head-to-tail” arrangement), thus inducing a large bathochromic shift on crystallization. However, the “head-to-tail” arrangement is not available in indigo. So the bathochromic shift is relatively small on going from solution to the solids state.
The states of dispersion of the charge control agents (CCAs) in a toner were investigated by electron probe micro analyzer (EPMA) scanning on the cut surface of the toner flake and were quantitatively discussed with the image processing of the CCA map obtained from the EPMA measurement. The correlation between the CCA particle size and the tribo-electric charging property of the mono-component was found, in which the optimum volume-average CCA size to maximize the tribo-electric charge existed. It was found by the XPS measurement that the CCA density on the toner surface was higher than that in the toner. EPMA and XPS are useful for the quantitative analysis of CCA in and on toner.