Suppression filters are used to filter out certain wavelength ranges in the visible or non-visible parts of the spectrum in order to obtain specific image information.
Daylight suppression filters prevent visible light from impinging on the image information. The image is only generated across those UV and/or IR ranges of the spectrum to which the camera sensor is still sensitive. The capture of fluorescent objects is an example of their use.
Daylight suppression filters are often used together with a certain UV and IR illumination to utilise the specific reflexion of the captured object.