Do you have a source for color standards related to fruits and vegetables?

USDA/AMS is the most general source for visual color standards for fruits and vegetables and offers a catalogue of color comparators and equipment they have available.

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Do you have references for the equivalency of CIE inverse instrument geometries?

FAQ: “…. the schema of the principle of measuring shows other way of light (source of light -> sample -> sphere -> detector) than our ColorQuest (source of light -> sphere -> sample ->  detector). Please can you explain me difference between both construction? difference between both results of measuring?”

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Can you explain the LabScan XE 0:45 inverted geometry?

FAQ: “Straight from the LSXE Pro-forma, the LabScan XE sample ports are described as:

Port Insert, 3-mm illuminated area; 5-mm measured area
Port Insert, 6-mm illuminated area; 10-mm measured area
Port Insert, 13-mm illuminated area; 17-mm measured area
Port Insert, 25-mm illuminated area; 30-mm measured area
Port Insert, 44-mm illuminated area; 50-mm measured area

I always thought that the measured area was smaller than the illuminated area. Have the illuminated/measured area in the Pro-forma been transposed? Seems like it!”

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How can I use EasyMatch QC to measure Contrast Ratio Opacity?

Contrast Ratio Opacity measurement quantifies how opaque a sheet sample using two readings. One reading is taken with the black glass or light trap backing the sample at the port. The second reading is taken with the sample backed by a white tile or the white sample clamp insert. EasyMatch QC will prompt you for the proper backing when taking opacity measurements.

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Do you have a source for Magnesium Carbonate powder as top-of-scale?

For measuring the brightness of some materials, some dated industrial methods cite a Magnesium Carbonate block standard to be set to Y = 100% in reflectance. This is a very old top-of-scale standard and HunterLab does not recommend using it.

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The details of how HunterLab sphere instruments conform to ASTM D1003 Section 8: Procedure B Spectrophotometer for transmission haze measurement

HunterLab sphere instruments with CIE d/8 geometries conform to the requirements of ASTM D1003 Section 8: Procedure B Spectrophotometer. The measurement of transmission haze using Procedure B instruments will be in close agreement with ASTM D1003 Procedure A Haze meter.

Here is a more detailed description of how the HunterLab UltraScan PRO, UltraScan VIS and ColorQuest XE meet the requirements of Section 8.

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Sources for BRDF and BSDF Equipment and Testing Services

In industrial colorimetry of QA non-luminous materials, assumptions are made that light reflected from or transmitted through a surface is relatively uniform, with only diffuse and specular components. To promote inter-instrument agreement, the CIE geometries for collecting the reflected or transmitted signal of non-luminous materials are standardized into directional and diffuse sphere types.

Prismatic highway signage materials tend to reflect light more in a retro-reflective direction than any other. This is the type of material where a BRDF scattering profile would be useful to know in the research stage.

Prismatic highway signage materials tend to reflect light more in a retro-reflective direction than in any other. This is the type of material where a BRDF scattering profile would be useful to know in the research stage.

BRDF measurement serves as more of a research tool when you want to precisely quantify the pattern of light reflecting from a sample surface, or the pattern of light being transmitted through a clear material. Typical materials would be coated surfaces, plastics, films and metals.

Another major application area for BRDF measurement is quantifying the illumination pattern from self luminous light sources such as LEDs and HID lamps; and luminaires such as automotive displays, and architectural lighting.

HunterLab does not make BRDF/BSDF equipment but here are some further resources for equipment and measurement services:

Lighting Sciences Inc.
Scottsdale, AZ  85260 USA
LabSphere, Inc.
North Sutton, NH 03260 USA

Radiant Zemax

Redmond, WA 98053 USA


KU Leuven, dept ESAT, Technologiecampus Gent (KAHO Sint-Lieven)

Light & Lighting Laboratory

Gebroeders De Smetstraat 1, 9000 Gent (Belgium)

+32 9 265 87 13