As you know, the color we perceive is a reflection of light. If there were no light there would be no color. Depending on the amount of light that a body can absorb and reflect, we will perceive one color or another. This is a very important concept to keep in mind when working in design printing.
Two identical colors can produce a different visual sensation if they are observed under a different light source, or if their surroundings are different. These colors are called metameric. To avoid this phenomenon, the printed elements or any prepress test should be observed under standardized conditions using standardized lamps and that provide us with the same light conditions for all observers and elements to be analyzed. There are different types of metamerism that are not reduced to lighting and that may affect our printed designs.
- Illuminance metamerism: It is the most common. It occurs when two samples coincide when seen under a certain type of light, but when the light source is modified, significant differences in color appear between both samples.
- Geometric metamerism: Two equal color samples can be perceived as different if the viewing angle of the object changes. This occurs since the reflectance of certain materials changes depending on the viewing angle.
- The observer metamerism: It is due to subjective differences in the appreciation of color between the different observers. Of course, the individual who receives the information is a decisive element in the process. This is generally due to biological or physiological causes, such as the difference of the sensitive cones (channel for the reception of color in the human eye). This obviously means that two people can perceive the same color sample differently.
- Field metamerism: In this case, the differences in color perception can be presented with a single observer. This occurs by positions of the observed object, with respect to the observer. That is, a small object can illuminate only the central part of the retina, where the cones sensitive to long (or medium, or short) wavelength radiation could be absent, while if the size increases, the part also increases of the illuminated retina and respectively the number of sensitive cones.