Photoreactivation

Photoreactivation is the restoration of the original state of chemical compounds exposed to light. For example, restoration of pigment in a photosensitive material after development. The photoreactivation process was first discovered by studying the recrystallization of magnesium metal in germanium supravite after short-term irradiation with ultraviolet light. In the method of electrochemical analysis there is an analogy with photoreactivity. Photoregeneration (from the Greek phos - light, radiant energy, and regeneratio - renewal), light reactivation, restoration of the functional properties of animal and plant tissues damaged by photodamaged agents or radiation under the influence of short-wave light of the visible, near and far infrared ranges. Photoreparative restoration occurs through DNA synthesis. During photodifferentiation, the photoreceptor apparatus develops from the normal epitheloid differential and then switches to photoreceptor function.

Photoreactivate - to render less damaged or usable again a material consisting of particulate matter, paint, ink, etc., which has been damaged by light, for example due to contact with or exposure to a series of photographs. Due to the typical reaction to only certain types of light, it is also common for "photographic" discs. This reaction can change the tone, color, contrast or brightness of the image, or create shadows or ghosting depending on how the light source was set.