A densitometer is an instrument used to measure the density of materials, particularly in photography and printing. It quantifies how much light passes through or reflects off a surface, helping to assess the quality and consistency of images. Densitometers are essential tools in the fields of photography, graphic design, and printing. There are different types of densitometers, including transmission and reflection densitometers. Transmission densitometers measure light passing through a transparent material, while reflection densitometers measure light bouncing off a surface. These devices help professionals ensure accurate color reproduction and maintain high standards in their work.