The authors are actively involved in the development of Elgraphy: a novel image acquiring system that combines electrophotography and liquid crystal technology. The organic photosensor used in Elgraphy (Elgraphic photosensor) exhibits enhanced hole injection induced by a negative space charge trapped at the electrode/photoconductive layer interface, thus giving rise to photocurrent amplification. A new type of photosensor that contains a PICAL (Photoinduced Current Amplifying Layer) between the transparent electrode and the CGL was fabricated. This three layer sensor was found to exhibit significantly larger photocurrent amplification than two layer sensors, that is, the dark current was smaller and the photocurrent was larger in the steady state when the proper voltage was applied. An investigation into how the resistivity of the PICAL and CGL affect the dark current and photocurrent of the three layer photosensor revealed the mechanism involved. The transient variation in the electric field across the PICAL promotes the injection of holes from the electrode, thus enhancing photocurrent amplification. In areas of the sensor that are not exposed to light, the larger resistance of the CGL reduces the voltage across the PICAL, suppressing hole injection from the electrode. In contrast, in areas that are exposed to light, the resistance of the CGL is smaller and the voltage across the PICAL is larger, thus enhancing hole injection.

Image quality of hardcopy is significantly influenced by paper properties. In this article, two kinds of image, a hardcopy and an image projected onto paper, are analyzed using a function based on the Modulation Transfer Function (MTF) of paper, and evaluated by observer rating experiments. As a result, good correlation was obtained between the function values and the observer rating values. It is shown experimentally that the reflectance and MTF of paper are of significant importance in the image quality of hardcopy.

An important process in remote sensing is spectral unmixing which is used to obtain a set of species concentration maps known as abundance images. Linear pixel unmixing, also known as linear mixture modeling, assumes that the spectral signature of each pixel vector is the linear combination of a limited set of fundamental spectral components known as end-members. Thus end-member selection is the crucial first step in the spectral unmixing process. A conveniently parameterized method for determining the appropriate set of end-members for a given set of multispectral images is proposed. The end-members are obtained from a thematic map generated from a modified ISODATA clustering procedure that uses the spectral angle criterion, instead of the common Euclidean distance criterion. The centroids of the compact and well-populated clusters are selected as candidate end-members. The advantages of this technique over common mathematical and manual end-member selection techniques are, (1) the resulting end-members correspond to physically identifiable, and likely pure, species on the ground, (2) the residual error is relatively small, and (3) minimal human interaction time is required. The proposed spectral unmixing procedure was implemented in C and has been successfully applied to test imagery from various platforms including LANDSAT 5 MSS (79 m GSD) and NOAA's AVHRR (1.1 km GSD).

This article examines trends over the last three decades of selected attributes for copier and printer products using xerography and thermal ink jet marking technologies. Relationships are identified between attributes that consolidate data and revealunderlying trends. An engineering performance metric is examined, useful for interpreting the trends. The analysis forms a foundation that could possibly be extended to develop projections of key performance attributes for the near future.

In single component development, a monolayer of charged toner is put on a donor roll and presented to a charged image on a photoreceptor. The donor and photoreceptor can either be put in contact or development can occur across a small gap between the photoreceptor and the donor roll. When there is a gap, one can directly observe the toners traversing the gap optically. We have designed a system where we capture the image of the transmitted light through the development gap with a high resolution CCD camera. From these digital images, we can quantitatively extract the toner density, toner size and toner velocity as the particles traverse the nip. Using time delay photography with microsecond resolution we measure the response of the cloud to incoming images. Using an organic film, which can form a permanent latent image, we are able to capture images of fine line development. Quantifying the density and motion of toners in single component development across a gap has allowed us to generate accurate physical models of the development process.

Photographic properties of 1-benzyl-1,4-dihydronicotinamide (BNAH) are studied for better understanding of the mechanism of the production of high contrast by the infectious development which is induced by the combination of a pyridinium salt and Metol-ascorbate developer. Treatment of internally chemically sensitized silver bromide core/shell emulsion by BNAH and redox buffer followed by development gave high internal fog density. It has been suggested in that the oxidation product of BNAH by redox buffer injects electrons into the conduction band of silver bromide grains, resulting in the formation of fog centers inside the grains. Results support the hypothesis that dihydropyridine works as an intermediate in the production of high contrast by the infectious development in the presence of a pyridinium salt.

This study examined the supersensitization of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene (TAI) in silver chloride emulsions. A systematic investigation on the concentration of TAI and the order of adding TAI and dyes had been carried out. It was discovered that the supersensitization efficiency of TAI varied greatly with the order of adding TAI and the concentration of TAI. The spectrometry study suggested that TAI could intensify the formation of the J-aggregate of dye and had quite different effects on the absorption spectra and spectral distribution of emulsion sensitivity when added in different orders.

We have provided evidence, from fluorimetric titration and analysis of the spectral distribution of fluorescence. that representative symmetrical cyanine dyes, DTCI and DTDCI, form 1:1 complexes with photographic stabilizers, 2-methylbenzimidazole (MeBz), 2-mercaptobenzoxazole (MBO), tetraazaindene (TAI), and the conjugate anions of the latter two compounds, in solution. AM1 semi-empirical and molecular mechanics calculations are introduced to interpret these results. Complex formation is consistent with the reported role of these stabilizers in supersensitization given the following possibilities: (1) the complexes may be adsorbed to silver halide surfaces in preference to free dye; (2) incorporation of the complex can disrupt a J-aggregate of the dye, with concomitant decrease in recombination probability in the aggregate; and, (3) insofar as computations suggest a partial charge transfer character to the complexes, they may be energy trapping sites on the grain surface, where electron injection into the grain is facilitated.

A two-step process for the formation of sensitivity centers different from earlier described two-step processes was found for sulfur sensitized emulsions. After deposition of sulfur in the first step, it was found that the second step does not consist of rearrangement of sulfur over the surface, but of the supply of silver interstitial ions towards the deposited sulfur clusters. The two processes could be separated by adsorbing and desorbing TAI (4-hydroxy-1, 3,3a, 7-tetraazaindene) at/from the silver halide surface. When 1.5 mmol TAI/mol Ag is added before the sulfur reaction, the silver interstitials are immobilized but sulfur still can be deposited at the same level. By lowering the pH to 2.50 after this sulfur reaction, TAI is desorbed from the surface and the released interstitials then cause a restoration of the properties of a sulfur system without TAI. These effects could be demonstrated via diffuse reflectance spectroscopy (DRS), sensitometry and dielectric loss measurements. We could also confirm the isolation of silver sulfide clusters by TAI from other chemicals in the solution, by adsorption of TAI on the clusters.

We propose a model for a sulfur-plus-gold sensitization center, which is derived by replacing one of two interstitial silver ions with a monovalent gold ion in a model for sulfur sensitization center proposed in this series of papers, and predict that (a) the incorporation of gold ions into silver halide grains is enhanced by the presence of sulfur sensitization centers owing to stronger bond formation of sulfide ions with gold ions relative to that with silver ions, and that (b) an electron trap for a sulfur-plus-gold sensitization center is shallower and has larger cross section than that fur a sulfur sensitization center, since a gold ion is larger than a silver ion. The prediction (a) was supported by the measurement of the amount of gold ions incorporated into AgBr grains by means of an isotopic tracer technique with a gold sensitizer labeled with ¹⁹⁸Au. The prediction (b) was supported by the measurements of the activation energy and frequency factor of the rate of development of developer fog, which resulted from the electron transfer from a developer to sensitization centers.