The human eye perceives color based on how different wavelengths are recognized and interpreted by the brain. This can vary from person to person, which is why color is often the subject of debate and why two people can have vastly different interpretations of the same shade in a painting or garment.
In the field of machine vision, we face similar challenges in determining what color a color actually is.
Measuring color accurately is difficult and depends on the method used. There are numerous factors that can affect the color that a camera perceives, and the challenge is to present this color in a consistent manner that is independent of human perception.
A color is simply a reflection of a specific spectrum of wavelengths that is not absorbed by the material the light strikes. Light sources, the material that the light passes through, and external factors like filters and lenses can all impact the perceived color.
To accurately define a color, you need a standardized light source and a color table to calibrate the system against. There are various suppliers of these color tables, but it's important to note that they are sensitive to sunlight and must be stored in darkness to ensure consistent results when recalibrating.
To match the measured color to the standard color space, multiple calibrations are often necessary.
Cameras themselves tend to be similar, but light sources can differ greatly, which is why calibrations must be performed each time the light source changes. Other factors, such as lens coating, can also impact accuracy and must be taken into consideration during calibration.
At JLI, we have a deep understanding of color, light, and the nuances of accurate color measurement. We have developed a series of calibration tools that provide precise color detection and have helped our international customers maintain consistent control over their colored products throughout the production process, from supplier to final product.