Measuring a color of a target coating

A method of measuring color of a target coating comprising:

• illuminating the target coating with a beam of electromagnetic radiation at an entrance angle, where a spherical coordinate system is used, where a surface of the target coating is a reference plane of the spherical coordinate system, an origin of the spherical coordinate system is a point about where the beam impacts the surface of the target coating, a zenith of the spherical coordinate system is a line normal to the surface of the target coating, wherein the entrance angle is a polar angle measured from the zenith, wherein the beam is defined with an azimuth angle of 0, wherein the target coating comprises flakes, wherein a target population of flakes is defined by all the flakes in the target population of flakes having the same angled flake normal polar angle, and wherein the target population of flakes have a plurality of flake normal azimuth angles;
• measuring an intensity of the electromagnetic radiation reflected from the target population of flakes having a first flake normal azimuth angle of the plurality of flake normal azimuth angles;
• and
• measuring the intensity of the electromagnetic radiation reflected from the target population of flakes having a second flake normal azimuth angle of the plurality of flake normal azimuth angles, where the second flake normal azimuth angle is different than the first flake normal azimuth angle.

A method of measuring color of a target coating comprising:

• illuminating the target coating with a beam of electromagnetic radiation at an entrance angle, where a spherical coordinate system is used, where a surface of the target coating is a reference plane of the spherical coordinate system, an origin of the spherical coordinate system is about a point where the beam impacts the surface of the target coating, a zenith of the spherical coordinate system is a line normal to the surface of the target coating, wherein the entrance angle is a polar angle measured from the zenith, wherein the beam is defined with an azimuth angle of 0, wherein the target coating comprises flakes, wherein a target population of flakes is defined by all the flakes in the target population of flakes having the same angled flake normal polar angle, and wherein the beam illuminates the target population of flakes;
• measuring an intensity of the electromagnetic radiation with a first detector positioned at a first polar angle measured from the zenith, wherein the first detector is positioned to receive electromagnetic radiation reflected from the beam by the target population of flakes;
• and
• measuring the intensity of the electromagnetic radiation with a second detector positioned at a second polar angle measured from the zenith, wherein the second polar angle is different than the first polar angle, wherein the second detector is positioned to receive electromagnetic radiation reflected from the beam by the target population of flakes.