An optical inspection technique is evaluated for documenting the overall condition and for mapping the extent of tarnish on the surface of 19^th century Daguerreotypes. The technique exploits the unique optical properties of Daguerreotypes to distinguish between light absorption and scattering by the daguerreian image. Combined with a digital imaging system, the technique provides an efficient tool for documenting a Daguerreotype's condition, for determining the optimal treatment exposure in different areas of the image, for monitoring the treatment progress, and for forecasting the results of natural aging or attempts at restoration. Examples of optical inspection and computer simulation of the visual appearance of a Daguerreotype versus different restoration treatments are presented.

It is well known that the spectral sensitivities (SS) for color imaging devices should satisfy the Luther condition that requires SS to be linear combinations of the CIE color matching functions. In practice, it is difficult to construct an SS exactly to meet this condition. Some quality factors such as q-factor for single SS by Neugebauer and μ-factor for a set of SS by Vora et al. were introduced in order to describe the deviation of SS from their nearest color mixture curves. In this article, a simple method is presented to implement an evaluation platform for the above two quality factors. A series of hypothetical spectral sensitivities are constructed with cubic spline functions with shape and peak position of the SS parametrically varied. The evaluation plat-form is used to optimize these SS parameters to obtain a maximum quality factor. Furthermore, the improvement of quality factor by adding a fourth SS is proposed and the relationship between quality factor and human perceptual judgement is discussed in this article.

We propose a new algorithm to obtain the color matching functions of any digital camera, with correct weights and white balance, from the relative scaling of their complete (3-D) spectral sensitivities obtained from real spectroradiometric data. Thanks to this algorithm, it is possible to predict the RGB digital levels of any digital camera in realistic illumination-scene environments—spatially non-uniform illumination field, variable chromaticity and large dynamic range of luminance levels—opening the possibility of transforming any digital camera into a tele-colorimeter. The illumination-scene test was the Macbeth Color-Checker Chart under three different light sources (halogen, metal halide and daylight fluorescent lamps), provided by a non-standard light box. The results confirmed that it is possible to predict any RGB digital levels exclusively by varying the f-number of the camera zoom lens.

In color imaging technologies one of the major parts of the scanning procedure is processing the raw RGB scanner data to make it suitable for printing on a given CMYK output device. The processing typically involves applying a number of technical and aesthetic, iteratively developed edits. These edits are stored in a proprietary file format, i.e. a type of vendor-specific macro file. There has been a recent shift from this closed loop type of color control to the open system of color management such as that specified by the International Color Consortium (ICC). ICC color managed workflows can only use a universally agreed file called a profile, and not proprietary user edit files. It may have taken a long time to perfect the proprietary edits and users will not want to lose them when they migrate to the new ICC workflows. This article describes a process that allows users to convert color edit information from a vendor-specific proprietary edit file into an ICC profile. The proposed system works by analyzing the proprietary edit information and then incorporating this information into an input profile. The application of the input profile and an output profile then produces a set of processed CMYK values that, when printed on the target printer produce essentially the same result as that achieved through the proprietary route. As a major part of the process relies on the generation of an accurate input profile, a polynomial fitting process and an empirical process are investigated for use in generating the transform relationship. This research also considers the reversibility of the output profile and a process to ensure accurate reversibility of the output profile is presented. A discussion is presented on the choice of rendering intents available and the different situations where each would be appropriate to use. Experimental results are presented for the whole process based on a test transparency that contains an image of a Macbeth ColorChecker chart. Quantitative results are presented to show how an ICC profiled system can be created that mimics a given proprietary reproduction style to within 2ΔE. This research demonstrates how novel image engineering applications can be constructed from within the ICC framework.

High quality reproductions made by prepress operators were studied in order to derive gamut mapping strategies. Ektachrome transparencies were reproduced on gloss coated and newsprint hard copy media, and the implicit mapping strategies in dimensions of hue, lightness and chroma were analyzed. The results supported some elements of the CARISMA gamut mapping algorithm, including a shift in hue towards the colorant primaries of the reproduction media and (for gloss coated media only) linear lightness scaling from the minimum and maximum L^* lightness of the image to those of the reproduction media. Compression of lightness and chroma towards the achromatic axis was found to be non-linear, and to have a variable convergence point. A gamut mapping algorithm incorporating these features (Graphic Arts Media Mapping Algorithm or GAMMA) was compared to other mapping methods in a transparency-to-newsprint workflow. The experiment compared different methods of determining the achromatic convergence point in simultaneous lightness-chroma compression, and compared linear compression against a non-linear distance-weighted compression. Non-linear compression methods and variable, lightness and chroma dependent convergence points performed better than those with linear compression and fixed convergence points.

Three-dimensional (3D) Gamma Compression Gamut Mapping Algorithm (GMA) is proposed in this study. Currently Gamma-Compression GMA has been designed to work in two-dimensional (2D) Lightness–Chroma planes segmented by primary and secondary hue regions. The advanced 3D GMA is expected to work in 3D uniform color space without color segmentation. This article describes the 3D GMA based on the concept of Image-to-Device (I-D). Considering color gamut relationships between source image and printer device, the Gamma-Compression GMA is applied to the 3D shell shapes in CIE L^*a^*b^* space. 3D gamut shells of a source image and printer device are formed by connecting the surface points located at their gamut surfaces. The surface polygon meshes or parametric cubic surfaces are built up from these most outside color points, and true seamless 3D mapping is performed. It is shown that the GMA coupled with 3D gamut compression and multimapping directions resulted in the better rendition than 2D nonlinear GMAs. It is also shown that 3D Gamma-Compression GMA works better than two known 3D GMAs, CARISMA and minimum ΔE₉₄ clipping. Two kinds of focal point decision rules, Image Lightness Division (ILD) and Focal Lightness Scaling (FLS), are introduced to find the optimum multimapping directions.

The properties of a thiocyanate free gold latensification solution are explored. A dilute solution of potassium tetrachloroaurate (III) produces photographic speeds almost as high as the conventional gold latensification formulation that contains potassium thiocyanate. During latensification, gold plates onto sub-image centers rather than replacing silver in those centers.

Although radiowave photoconductivity measurement was expected to be sensitive enough to detect the transient behavior not only of photoelectrons but also of positive holes in silver halide grains, it was not necessarily successful owing to the lack of its stability and reproducibility. In this investigation, we made a theoretical study and simulation of this measurement technique and developed a new apparatus for it, with significantly improved stability and reproducibility. The coefficient of variation of the photoconductivity of AgBr grains with positive holes as carriers by the new apparatus was 3.6%, while that by the old one was 33.8%. It was demonstrated that the new apparatus was sensitive and reproducible enough to measure small changes in photoconductivity of silver halide grains with positive holes as carriers. These changes were undetectable by the previous one.

Electronic properties of chemically produced silver clusters were studied using an internally sulfur-sensitized core-shell emulsion. Upon reduction sensitizing the shell of this emulsion with either dimethylamineborane or high pH the internal speed was enhanced. This is clear evidence that the surface silver clusters are hole removing sites. For our materials and experimental conditions, no evidence was found to support the hypothesis that any of the chemically produced silver clusters, except for those leading to fog, had the characteristics of irreversible electron traps.