Definition: Corrective filter – is an external filter that is placed between optics and sensor. Different companies use different corrective filters for the same sensors and thus receive different precision of color capturing.

As it is already well known, an additional corrective filter can significantly improve quality of the images. Corrective filters are able not only to delete ultraviolet and infrared parts of the spectrum (invisible to a human eye), but also to correct the part of the spectrum visible to the human eye. Many camera manufacturers use filters for the first purpose – removal of ultraviolet and infrared light. However, according to KWEII research, no one has yet used filters for the second purpose – correction of the visible part – because specialists developing cameras and camcorders do not have precise directions supported by strong color theory.

Usually a specific filter is chosen after series of experiments with many different filters. In order to formulate spectral characteristics of the theoretically best corrective filter (which will serve both purposes) a strong Color Theory, able to explain how this corrective filter would work and how it would affect the whole color-capturing process, is necessary. KWEII can calculate optimal spectral characteristics of the additional corrective filter. If a Camera Manufacturer decides not to manufacture a new filter, KWEII can review parameters of the available filters and recommend the best one.

Application of best ultraviolet and infrared filter (dotted black) to ICX282AQF reduces 1.67 times the color capturing error. Application of optimal filter (solid black) to ICX282AQF reduces 2.20 times the color capturing error. Colored thin lines represent spectral sensitivity of sensors with micro filters. Thick colored lines represent spectral sensitivity of sensors with micro filters and optimal filter.