Pigment processes are photographic printing methods that create positive images by exploiting the light-sensitive properties of bichromated colloids. When exposed to light, these colloids undergo chemical changes that alter their physical characteristics, allowing pigments to adhere selectively and form an image.
One well-known example is the gum bichromate process, where pigments mixed with a light-sensitive solution are applied to paper and developed with water. Pigment processes are prized for their artistic flexibility, allowing photographers and printmakers to produce richly textured, hand-crafted images with unique tonal qualities and creative control.