A color filter separates the incident light into two portions: one portion is transmitted and a second portion is removed from the full spectrum. This splitting of the spectrum can be achieved by different techniques, e.g. reflection or absorption. PRiSMA uses a combination of both technologies to achieve optimum filtration efficiency.

According to the laws of optics, it follows that an absorption filter, which removes blue light from the spectrum, looks yellow. Similarly, a filter that eliminates the yellow component would look blue. According to the principle of additive color mixing, which applies when colored light is mixed, the colors red, green and blue together produce white light. If we now take out the blue component, red and green light remain, which together produce the perception of yellow.

For this reason, blue light filters that work effectively always look yellow. In this way, the consumer can judge at any time, even without measuring instruments, whether a filter can really deliver the promised filter effect, because a pale yellow filter allows many more blue components to pass through than a filter in a strong yellow or saturated orange tint. However, this rule of thumb only applies to pale filter strengths. Ultimately, only a measurement can provide an exact assessment.