Interpretation of film contrast terms

Film contrast noun explanation:? The difference in image density obtained by filming a scene is also called contrast. The contrast of color film not only indicates the difference of degree, but also includes the difference of color and saturation.

Cinematographic film is a photosensitive material coated with emulsion on a transparent flexible film base, including negative film for cinematography, positive film for printing and reproduction, intermediate film for reproduction and vocal cords for recording. These films are basically the same in structure, and they are composed of two parts: photosensitive silver halide gelatin emulsion layer and supporting film base layer.

Main components of emulsion:

For silver halide suspended in gelatin, gelatin can not only suspend silver halide without precipitation, but also contain sensitizing substances, which can increase the sensitivity of emulsion to light and make the film have higher sensitivity to meet the requirements of film formation. Silver halide itself is only sensitive to blue-violet light with a wavelength of 400~500 nm, and the brightness of the photographed image is different from that of various colors seen by human eyes, so it is called color-blind film.

1873, German H.W. vogel discovered that dyes can expand the photosensitive range of silver halide, so he made a positive film that can perceive both blue-violet light and green light. After 1906, various cyanine dyes appeared one after another, which made the photosensitive range of film develop to a long wavelength and developed a full-color film sensitive to visible light.

Infrared film was also born:

In addition, with the development of photosensitive range to infrared region, infrared film was born.

Infrared film is mainly used for aerial photography, special effects and special photography. Black-and-white films used for shooting are generally full color, while those used for printing black-and-white film copies are generally color blind. Although full-color photography can make the layering of various colors clear and bring a lot of convenience to artistic creation, the tone of black-and-white movies can only be gray with different shades, which is far from meeting people's requirements of expressing colorful nature.

Therefore, many physicists, chemists and photographers have studied color photography methods.

According to the color classification, it can be divided into black-and-white film and color film.