# Standard Geometries Used to Measure Colors

Reviewed by Anurag Mishra (Sr. Technical Consultant)

Measuring Geometries plays a significant role in measuring and assessing the color of the different sample. The surface and the structural features of the sample depicts spectral differences due to the incident radiations that transmitted or reflected in various directions. The aperture angle and the angle of incidence of the illuminating beam of rays directly affect the colorimetric results.

CIE standard recommends four primary measuring geometries for colorimetry that helps to measure the colors of different products efficiently. Out of these four geometries, two of them are 0°/45° and 45°/0°.

• 0°/45° Measuring geometry: – This type of geometrical measurements explains that illumination to the sample is provided under 0°, and measurements are done under 45°.
• 45°/0° Measuring geometry: This type of geometrical measurements explains that illumination to the sample is provided under 45°and measurements are done under 0°

In 45°/0° measuring geometry, the mirror reflection component is removed purposefully to avoid alterations in the final results due to the presence of gloss. Under this geometry, the surface shows the structural direction that yields different results depending on the relative position with respect to the light. In these cases, the geometry with diffuse illumination can be chosen.

On another hand, another two geometries that are recommended by CIE are 0°/d and d/0°.

Here, d stands for the observation of light that diffusely scattered by the specimen by means the wall of an integrating sphere or diffuse illumination of samples.

• 0°/d Measuring geometry: This type of geometrical measurements explains that illumination to the sample is provided under 0°, and measurements are done on the sphere.
• d/0° Measuring geometry: This type of geometrical measurements explains that Diffuse illumination of the sample and measurement are done under 0°

Testronix offers high-quality of color measurement instruments that work on these measuring geometries. For more information on these instruments, visit: www.testronixinstruments.com