The long term stability of photographic prints is known to be sensitive to a variety of factors. These factors include the chemical composition of the inks and media, as well as the ambient environmental conditions-light, heat, humidity, and air quality-under which the prints are stored and/or displayed. In order to correlate the results of accelerated testing in the laboratory with what actually happens to a photographic print under long term, real world conditions, it is necessary to better understand the typical ambient environmental conditions under which the prints are being displayed and/or stored. In phase I of this study, light levels, spectral energy distributions, temperatures, and humidities were monitored for 6-12 months in eight homes in each of four cities around the world (Rochester, Los Angeles, London, and Melbourne). For phase II, eight homes in each of four additional cities (São Paulo, Shanghai, Atlanta, and Tokyo) were monitored for 10-12 months. A key finding of these studies is that ambient home display conditions are dominated by relatively low intensity, indirect, window-filtered daylight. The long term temperature and humidity levels averaged close to the commonly cited conditions of 25 °C, 50% relative humidity, with the exception of Shanghai and São Paulo where somewhat higher levels were observed. These results are discussed in the context of designing and interpreting improved accelerated image stability test methods.

Considering luminance contrast to comprise the building blocks of the photographic language, we aimed to study the connection between viewer's contrast discrimination performance in black-and-white photographs with various contrast reproductions, and their aesthetic appeal. In a previous study we examined the viewer's ability to discriminate contrast increments, applied to discrete regions of the characteristic curves of gray scales versus photographs of Ansel Adams. The photographs belonged to three conceptual categories: portrait, landscape, and architecture. Whereas, contrast discrimination performance in gray scales was very poor in reproductions with altered contrast in the shadows, a significant improvement in performance was observed in the photographs. In the present study subjects performed a contrast preference evaluation task, in which, the reproductions of the photographs were rated for their aesthetic appeal on a five-point scale. The photographs were presented in random order, without indication as to which is the original photograph. Nevertheless, the viewers showed a general preference for photographs with contrast reproductions similar to the original. The results suggest a match between the viewers' and the photographer's preferences. Moreover, the preference decreased systematically with the contrast increment for all reproductions. This tendency seems to be independent of variations in category or spatial configuration. The results are in line with the observed contrast discrimination performance, and also consistent with the anchoring theory and recent propositions of biologically based rules for art creation and appreciation as manifestations of the function of the brain.

Distribution of ink jet ink in paper substrates and the consequences of ink penetration for printing color reproduction have been studied by combining microscopic image processing with spectroscopic analysis. The study focused on the effects of the composition of uncoated paper, for five laboratory papers plus two commercial products, all consisting of similar pulps but with different combinations of additives. In particular, it was observed that hydrophobizing internal size agents significantly reduced ink penetration, while their effect on paper optical properties was negligible. This observation thus made it possible to study experimentally the pure effects of ink penetration. Pairwise comparisons of prints on such laboratory papers with identical optical properties revealed remarkable impacts of ink penetration on optical density, causing color saturation reduction and color shift. These experimental observations confirmed the theoretical predictions.

The binding process of printing inks on the printing substrate is one of the final phases in the creative chain of a new product formation-the print. It is not only the expected mechanism of ink drying that influences the ink distribution on the substrate surface, but also the properties of the substrate itself. Many factors, like hydrophobicity, roughness, and porosity influence the ink distribution on both coated and uncoated papers. The aim of this study was to evaluate the applicability of several nondestructive methods in the analysis of vertical and radial ink distribution on diverse ink jet prints. What are the limits and the extent of confocal Raman, ultraviolet (UV) Raman, CLSM and Fourier-transform infrared (FTIR) PAS in the analysis of ink jet ink distribution in the z direction of the print? In the experiment, both dye- and pigment-based ink jet inks were printed on different types of coated and uncoated papers. The results show a correlation between the confocal Raman and CLSM methods for depth profiling. UV Raman proved useful in the surface analysis of prints while FTIR PAS was useful for measurements at low depth in the z direction. The applied microscopic and spectroscopic methods provide a precise distinction between the upper homogeneous and the inside nonhomogeneous ink layers. Sporadic streams of deeply penetrated ink jet ink were also detected.

Support vector regression is applied to the problem of estimating the chromaticity of the light illuminating a scene from a color histogram of an image of the scene. Illumination estimation is fundamental to white balancing digital color images and to understanding human color constancy. Under controlled experimental conditions, the support vector method is shown to perform well. Its performance is compared to other published methods including neural network color constancy, color by correlation, and shades of gray.

Most display characterization methods, such as the gain-offset-gamma model and S-curve model, generally assume that displays have two fundamental characteristics, channel-chromaticity constancy and channel independence. Consequently, based on the assumption of channel-chromaticity constancy, only one electro-optical transfer function (EOTF) is used for each channel to establish the relation between the digital input values and the output luminance levels. Meanwhile, based on the channel-independence assumption, the channel color values are simply summed to acquire mixed color values. However, these assumptions are not so applicable in the case of liquid crystal-based mobile displays. Accordingly, modifications are required to enable the application of conventional display characterization methods to mobile displays. Therefore, this study proposes the modeling of distinct EOTFs in terms of the Y, Y and Z values for each channel to consider the differences among the EOTFs resulting from channel-chromaticity inconstancy. In addition, to overcome the poor additivity property among the channels due to channel interaction, the proposed method also models and uses the EOTFs of the Y, Y and Z values for the interchannel components cyan, magenta, yellow, and gray. Experimental results confirm that the mobile display color values predicted by the proposed characterization method are more accurate than those predicted by other characterization methods due to considering the channel-chromaticity inconstancy and/or channel dependence of the display.

With the recent development of multiprimary display devices, the three primary colors (red, green, and blue) of a conventional display need to be decomposed into control values for a multiprimary display (MPD) under the constraints of tristimulus matching. To achieve tristimulus matching between such different display systems, the MPD color signals need to be estimated based on a device-independent color space, such as CIEXYZ or CIELAB. Yet, since the focus of a MPD is to display motion picture data, the color space conversion and multiprimary control value decomposition must be simplified. Accordingly, this paper presents a color signal decomposition method for a MPD using a three-dimensional look-up-table (3D LUT) in linearized LAB space. Linearized LAB space satisfies the linearity and additivity required for the color space conversion, and can easily construct a 3D LUT that considers the lightness, chroma, and hue. In addition, to reproduce moving picture data in a MPD, the proposed decomposition method uses a 3D LUT structure to reduce the hardware complexity and processing time. First, a 3D LUT that contains the gamut boundary points of the MPD is created to decompose the multiprimary control values. The chroma and multiprimary color signals for the gamut boundary are then stored in the 3D LUT along with the quantized hue and lightness values. Next, a quadrangular pyramid composed of four gamut boundary points and one lightness point on an achromatic axis is generated according to the input linearized LAB values. Consequently, MPD color signals can be obtained for the input values by interpolating between the multiprimary color signals for the gamut boundary points and the lightness point on an achromatic axis. Furthermore, additional gamut boundary points within 10° of the hue are used to interpolate the input values in regions that involve an abrupt change in the multiprimary control values to achieve a smooth change of hue. As a result, the proposed method guarantees computational efficiency and color signal continuity. Plus, less memory space is required when compared with conventional color decomposition methods.

A new monocomponent electrophotographic development system is introduced, in which nonmagnetic toner jumps the gap between the development roller and the photoreceptor only under the influence of the direct current electric fields of the latent image. This development system requires for its operation low toner adhesion, which is achieved by a patented toner formulation. Such a development system is ideally suited for a small size, low cost, color electrophotographic engine. A prototype color printer utilizing this unique development system in an image-on-image architecture has been implemented to demonstrate its printing capabilities. Photomicrographs of print samples are shown and the scalability and extendibility of this technology are discussed.

The steady state airflow and electric field distributions in a corona device (corotron) during charging of a moving dielectric substrate (photoreceptor) for different operating conditions are studied. The set of two-way, fully coupled electrohydrodynamics governing equations is used in the analysis and parametric studies are performed. The effects of wire voltage, photoreceptor speed, and device-substrate gap size on photoreceptor charging, airflow, charge density, and electrical potential are studied. It is shown that the charging is strongly affected by the wire voltage and the substrate speed. The results also show the importance of corona wind effect on the flow structure in the device.

In order to collectively study the factors influencing the developability of centers, the in situ measurement and analysis of the rate of development was made for various latent image centers and fog centers on AgBr grains with a variation of the kind of chemical sensitizations. The developability of these centers was analyzed from the viewpoints that the electron transfer from a developer to the electron-accepting level of a center should initiate the development, and that the height of the electron-accepting level of a center should be related to its size, chemical composition, band structure, the parity of the number of valence electrons in it, and the site for its formation. It was confirmed that the smallest developable center in AgBr emulsions was a fog center composed of two Au atoms while the smallest latent image centers in the emulsions with and without gold sensitization were Ag₂Au and Ag₄, respectively. The developabilities of these smallest centers were much smaller than those of larger ones. The developability of a center with a forbidden band as exemplified by Ag₂S (i.e., a fog center in a sulfur sensitized emulsion) was so small that several hundreds of nanoclusters per grain were needed to initiate the development of the grain.