Munsell 10YR Soil Color Chart under various light sources: A visual database

Hilda Deborah

This Munsell soil color chart (10YR) has been used to describe the colors of the Dead Sea fragments, e.g., in DJD 36. This database provides a visualization for the color chart under various light sources. It is aimed to show that documenting colors as we observe them is affected by the illumination under which the observation is carried out. It is therefore not an objective way to document color, because the documented color is more of a perceptual than a physical property of materials.

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Introduction

In the Discoveries in the Judaean Desert (DJD) series, we often find color as one of several physical descriptions of the Dead Sea fragments. In most of the volumes, we most often see the use of color terms such as brown and tan, and sometimes their variation. See the list of colors that have been used to describe Dead Sea materials in this colour database. The problem with the use of those terms is that they are not standardized, thus we cannot use it to derive or interpret, e.g., the degradation state of an object, solely based on those records. To use color objectively and in a standardized way, one must follow the protocols laid out in colorimetry, i.e., the science and technology used to quantify and describe physically the human color perception.

The colors of an object that we see is not their “true colors” as we might think it is. Rather, they are always a product of the characteristics of our visual system (e.g., normal vision or color-deficient), the color of the light source, and how the object responds to light (e.g., reflect or absorb). See the illustration below. Of course, this is not all there is to how we, humans, perceive colors. Our visual system is not only comprised of optical devices such as the lens and the retina, but also the more complex vision and cognitive processes. To use color as a physical and objective description of an object or material, we must use its physical property and not its perceived property.

True Colors Model

Especially in DJD 36, we can see the use of a standard color chart, i.e., Munsell soil color chart, to describe fragments. These descriptions are usually mentioned as, e.g., very pale brown 10YR 7.5/3. Such description refers to a specific color chip in the standard chart. Is this a better way to document color as a physical description? No, not necessarily. The documented color is still a perceived property instead of a physical one, because it is still affected by the light source. This database provides the color rendering of Munsell 10YR soil color chart under various light sources, to show how significant the color differences can be even if we only change the light source under which we observe them.

As a note, when we observe these different rendering, note that the colors of our computer screen and room lighting will be an extra factor to what we observe. Those who want to do a quantitative analysis of the Munsell 10YR soil color chart, the spectral reflectance of each color chip and their sRGB and hex color values under various light sources can be found in the excel file.