Richard N Ellson

UltraColor: a new gamut-mapping strategy

Many color calibration and enhancement strategies exist for digital systems. Typically, these approaches are optimized to work well with one class of images, but may produce unsatisfactory results for other types of images. For example, a colorimetric strategy may work well when printing photographic scenes, but may give inferior results for business graphic images because of device color gamut limitations. On the other hand, a color enhancement strategy that works well for business graphics images may distort the color reproduction of skintones and other important photographic colors. This paper describes a method for specifying different color mapping strategies in various regions of color space, while providing a mechanism for smooth transitions between the different regions. The method involves a two step process: (1) constraints are applied so some subset of the points in the input color space explicitly specifying the color mapping function; (2) the color mapping for the remainder of the color values is then determined using an interpolation algorithm that preserves continuity and smoothness. The interpolation algorithm that was developed is based on a computer graphics morphing technique. This method was used to develop the UltraColor gamut mapping strategy, which combines a colorimetric mapping for colors with low saturation levels, with a color enhancement technique for colors with high saturation levels. The result is a single color transformation that produces superior quality for all classes of imagery. UltraColor has been incorporated in several models of Kodak printers including the Kodak ColorEase PS and the Kodak XLS 8600 PS thermal dye sublimation printers.

Visualization of injection molding

Scientific visualization, a computer-generated graphical represen tation of scientific information, provides a global view of simula tion results and helps identify discrepencies between the real and simulated world. This article outlines the scientific visualization method and its application to the study of injection molding flows.

Depth quantization for polygonal consolidation from range data

Computer graphics rendering and the compression of range data with its associated color data impact the quality and speed of reconstructing photo realistic images from range/color scans of real world scenes. A method of consolidating orthographically scanned, quantized range data into polygons was developed with the intent of being both practical and efficient in its processing and storage of only the information required for producing a new photo-realistic image from nearly the same perspective as the original scan. Tests were performed on both actual range data and data extracted from the z-buffer of polygonal computer graphics renderings. In each case, for every range value a 24-bit color was associated with each range value. A polygon was constructed to represent the range and color data. Surface normals were calculated for each polygon, and consolidation of neighboring polygons was performed if their normals occupied the same quantized region of the Gaussian sphere. Results on polygonal consolidation ratios and reconstructed image quality as a function of quantization will be presented.