Comparison of Color Systems with Respect to Uniform Visual Spacing

Trajectory mapping: a new nonmetric scaling technique

Trajectory mapping is a new scaling technique designed to recover the parameterizations, axes, and paths used to traverse a feature space. Unlike with multidimensional scaling, there is no assumption that the space is homogeneous or metric. Although some metric ordering information is obtained with trajectory mapping, the main output is the feature parameterizations that partition the given domain of object samples into different categories. After an introductory example, the technique is further illustrated by using first a set of colors and then a collection of textures.

Colorimetry for the stain technologist. II. The specification of chromaticity difference

This paper describes the calculation of chromaticity difference. The text has been written specifically for the stain technologist and is largely self-contained. The concept of a uniform chromaticity scale (UCS) is described. A UCS is a diagram in which equal perceived differences in chromaticity are represented by equal distances anywhere on the diagram. UCSs are developed by transformations of the CIE 1931 chromaticity diagram, and may be linear (projective) or nonlinear. The effectiveness of the various transformations has been assessed using published data on discrimination of chromaticity. The usefulness of chromaticity difference calculations is illustrated by histological examples, including Romanowsky stained blood cells and Papanicolaou stained cells from the uterine cervix. Six UCSs are used in these examples, two projective and four nonlinear.