Mt. Baker Research L.L.C.
2921 Sylvan Street/P.O. Box 28370
Bellingham, Washington 98228-0370

Defining Color Standards

Phone: (360) 650-0771 E-mail: <jackroot@mtbakerresearch.com>

Mt. Baker Research L.L.C. Information

Color Gamut

Our color standards are used for instrument testing, calibration, and profiling. The charts on this page show that our standards offer the widest color gamut available in the international marketplace.

The 1st chart shows the color distribution of our 3 color sets in comparison with the chromatic CERAM BCRA Series II tiles.

CIELAB b* vs. a* gamut plot. Conditions: D65 Standard Illuminant. 2° Standard Observer. (8°/t) hemispherical specular-included geometry. Key to symbols: ◆, 36 chromatic color standards (Mt. Baker Research). ◆, 8 BCRA Series II tiles (Ceram Technology Ltd.). ━ & ━, chroma boundaries.

On this chart the closed solid lines represent the chroma contours for our chromatic standards vs. the BCRA Series II tiles. The CIELAB chroma, C*, corresponds to the scalar distance from the origin of the b* vs. a* chart to any data point.

The area enclosed within a chroma contour provides a convenient measure of the gamut of colors. The 8 BCRA Series II chromatic tiles define the color gamut enclosed by the blue solid line.

The color gamut for our tiles (enclosed by the red line) is defined by the 14 chromatic standards that exhibit the largest CIELAB chroma values. The other chromatic standards in our 3 color sets are distributed within the red chroma boundary. Many of our standards extend the available gamut of colors, and all of them span the gamut very well.

The next chart shows a measure of the gamut of colors that includes the CIELAB lightness parameter, L*.

CIELAB C* vs. L* gamut plot. The chroma, C*, is given by [a*² + b*²]^0.5. Conditions & Key to symbols: see preceding chart.

Over the full range of L* our chromatic standards increase the chroma and the available gamut of colors. This more complete coverage of color space will improve results for device testing, characterization, and profiling.

The next chart shows the characteristics of our neutral, or achromatic, standards vs. the neutral CERAM tiles and the GretagMacbeth ColorChecker Chart.

CIELAB L* vs. median reflectance factor (360 - 780 nm). Conditions: D65 Standard Illuminant. 2° Standard Observer. (8°/t) hemispherical specular-included geometry. Key to symbols: ◆, 13 achromatic standards (Mt. Baker Research). ◆, 11 CERAM achromatic tiles (Ceram Technology Ltd.). ◆, 6 neutral patches from the GretagMacbeth ColorChecker Chart (X-Rite, Inc.).

The error bars shown on this chart correspond to the CIELAB chroma, C*, values, which measure the deviation from neutrality. (For a perfectly neutral standard the value of C* is zero.) Our achromatic standards span the full range of L* with roughly comparable neutrality to the CERAM tiles.

The data for the ColorChecker Chart were reported by Dr. Noboru Ohta. You may download Dr. Ohta's data from the Resources page at the web site of the Munsell Color Science Laboratory. (Notes: The measurement geometry is not listed. The original reference is N. Ohta, "The Basis of Color Reproduction Engineering (Japanese)", published by Corona-sha Co. of Japan in 1997.)

The final charts in this series extend the 1st 2 (see above) by adding data for 44 chromatic color standards, which are not included in our 3 color sets. (We offer all of these standards on a special-order basis.)

CIELAB b* vs. a* gamut plot. Conditions: D65 Standard Illuminant. 2° Standard Observer. (8°/t) hemispherical specular-included geometry. Key to symbols: ◆, 80 chromatic standards (Mt. Baker Research). ◆, 8 BCRA Series II tiles (Ceram Technology Ltd.). ━ & ━, chroma boundaries.

As before, the color gamut for our tiles (enclosed by the red line) is defined by the 14 color standards that exhibit the largest CIELAB chroma values. The other chromatic standards are distributed within the red chroma boundary. Many of them extend the available gamut of colors (see below), and all of them span the gamut very well.

CIELAB C* vs. L* gamut plot. The chroma, C*, is given by [a*² + b*²]^0.5. Conditions & Key to symbols: see preceding chart.

Over the full range of L* our chromatic standards greatly increase the chroma and the available gamut of colors. This more complete coverage of color space will improve results for device testing, characterization, and profiling.

• Visit ColorAcademy or ColorTec for introductory tutorials on subjects related to light, color vision, and color measurement.
• Visit WebExhibits for a tutorial on color vision and visual perception.
• See Dr. Yoshi Ohno's technical article, "CIE Fundamentals for Color Measurements" for an overview of the CIE colorimetry system and color measurement.