Archive for May, 2019

A Common MacAdam Fail

Posted: May 24, 2019 in Uncategorized

The MacAdam ellipse is a Standard Deviation Color Matching (SDCM) protocol for describing visibility of human observers of differences of sources, by how far they deviate from a reference color. Each ellipse represents a standard deviation from the reference (center) source. It is generally accepted that within 3 MacAdam ellipses, most observers cannot discern a difference between two sources. At 4 steps, a significant sampling of observers would see a color difference. At 7, virtually everyone will see a difference. For a more complete background, there are numerous sources describing these details, such as https://en.wikipedia.org/wiki/MacAdam_ellipse. The shape of the ellipses varies by color, as human visual differentiation changes in both spectral sensitivity as well as range between sources.

With this, it would seem pretty straightforward that when someone claims their product, LED, or light sources fall within 2 or 3 steps, that it can be assumed that the difference between two sources from that provider will be unseen. Unfortunately, a common miss-interpretation and incorrect application of the MacAdam ellipse protocol creates an actual deviation that can be as much as double that stated. The illustration below shows how this happens. (more…)

The Adventure with Architectural SSL Magazine

In 2006, I pitched the idea of a magazine dedicated to Solid-State lighting technology as it applies directly to architecture with the owners of Construction Business Media. After a few pizza lunches and more convincing, they moved to creation of Architectural SSL magazine in time for Lightfair 2007 with its debut issue.

Since that debut 12 years ago, I have participated in editorial discussion and planning, contributed content to every issue with a market setting feature, a closing remarks Op Ed, white papers, judeged products, provided reviews of various products and provided general commentary on the progress of SSL into the lighting market. (more…)