Some explanation is in order. There are two views of the OSA-UCS planes, depending if they are orthogonal to the coordinates or are tilted. The normal vector relative to the screen for viewing the orthogonal planes is (0,0,1). The normal for viewing the tilted planes is (1,1,1). Note that the x and y coordinates are skewed by 45 degrees. The coordinates of the OSA-UCS are L, j, and g.

Only the full-step set is implemented in this applet. I did not explore visualizing the half-step set defined in the OSA-UCS. The control interface currently implemented is crude and minimal. I could be convinced to make improvements. The layout is poor, but look at the colors! They tend towards pastel, as the illuminating light source modelled is the viewing monitor white at full intensity. The OSA-UCS standard is limited by the color gamut pigments can achieve in D6500 Kelvin illumination. I can into some difficulties when precomputing the monitor RGB values for the various samples, as a few of the blue values were negative! There's more that could be explored with regard to gamut mapping to monitors.

This applet is based on the Macintosh program I developed during the course of my master's thesis. The applet requires Java version 1.1 or higher to be supported and 24-bit color to be rendered properly. The poorly documented and somewhat inefficient Java source code is available on request. The development platform was Sun JDK 1.2.2, tested on both Windows 95 and a Linux 2.2 kernel.

The formulae that specify the L,j,g coordinates can be found on page 18 of this paper.

Copyright © 1989-2000 by Jim W. Lai. All rights reserved.