The basis of this research is the manipulation of sensor excitation values to account for differences in observer or illuminant when spectral data are unknown. This touches on several related topics: color constancy, chromatic adaptation, and white balancing. The central premise is that these concepts make use of some form of intermediate color equivalency representation or waypoint system that makes comparison and color transformations possible. Differences between these concepts are related to the kind of color equivalency representation system used and how transformations are made into and out of it. A new sensor excitation normalization method was derived that has been optimized to predict changes in material color as Wpt (pronounced Waypoint) coordinates, which can be used to form a material adjustment transform. The prediction of such changes is also known as least dissimilar color matching. This is contrasted with a chromatic adaptation transform, which is optimized to predict corresponding color changes. As such a distinction is made between adaptation (which is based on corresponding color) and adjustment (which is based on other criteria). V

Variability in object appearance is common in everyday experience and this variability can generally be attributed to the relationships between viewing conditions and the composition of an object's spectral reflectances. This paper proposes that objects, illuminants, and observers can be evaluated using a Wpt (Waypoint) shift manifold (WSM), which is defined as a set of Wpt points associated with one or more objects, observers, and/or illuminants. Since spectral reflectances of an object can be decomposed to three components (a wavelength invariant nonselective component, a characteristic reflectance, and a metameric black reflectance), WSMs of any object for an observing condition is composed of three Wpt vectors associated with a perfect reflecting diffuser, the characteristic reflectance, and the metameric black reflectance of the object. Material shift potential (MSP) can be defined as shapes and orientations of object WSMs for evaluation and comparison of object colors. Experimental results show that MSP are dramatically influenced by Wpt vectors associated with the characteristic reflectance and the metameric black reflectance for an object rather than the Wpt vectors associated with nonselective reflectance. Thus, MSP can be preserved for objects having similar characteristic reflectances and metameric black reflectances. In other words, spectral reflectances that have been manipulated to have similar overall shapes exhibit similar color inconstancy.

A display tool has been developed to perform simulation and three-dimensional rendering of prints in the quest towards achieving improved soft proofing capabilities. It was desired through this 3D simulation that the gloss and surface properties of hardcopy prints be represented on a d i s p l a y, which are absent in current 2D soft proofing workflows. The procedure is described along with the relevant historical work. The major components of the workflow are identified as: the gloss prediction model, and the representation of this gloss on a display using computer graphics rendering techniques. Psychophysical experiments were carried out to evaluate the usefulness of this 3D simulation over current 2D soft proofing technique.

A set of invertible non-linear transforms was derived that adjusts Wpt (Waypoint) coordinates (based on Wpt normalization) to and from a perceptually more uniform coordinate system (WLab or Waypoint-Lab) than that provided by Wpt that allows for the advantageous features of Wpt to be directly applied to situations where other standard color spaces are typically used. The proposed transformations were found by optimizing for perceptual uniformity over both large and small color difference scales. The Munsell color order system was used as a representation for optimizing large-scale perceptual uniformity. Correlations with Munsell value, chroma and hue along with comparisons with CIELAB and CAM02-UCS were used to correct and assess overall large-scale uniformity. The DE* 94 color difference formula was used for optimization purposes for small-scale uniformity. A STRESS analysis was applied to compare color differences based on Euclidean WLab distances with color differences based upon DE* ab , DE* 94 , DE 00 , DIN99o, CIECAM02, and CAM02-UCS. It was found that WLab is a reasonably uniform material color equivalency space with small Euclidean WLab distances not being statistically different from DE* 94 , DE 00 , and Euclidean distances of DIN99o and CAM02-UCS under reference observing conditions.