Black-and-white photography

Monochrome photography is photography where each position on an image can record and show a different amount of light, but not a different hue. It includes all forms of black-and-white photography, which produce images containing tones of neutral grey ranging from black to white. Other hues besides grey, such as sepia, cyan or brown can also be used in monochrome photography. In the contemporary world, monochrome photography is mostly used for artistic purposes and certain technical imaging applications, rather than for visually accurate reproduction of scenes.

Most modern black-and-white films, called panchromatic films, record the entire visible spectrum. Some films are orthochromatic, recording visible light wavelengths shorter than 590 nanometers, in the blue to green range of the spectrum and are less sensitive to the longer wavelength range (i.e. orange-red) of the visible spectrum. Black-and-white photography is considered by some to be more subtle and interpretive, and less realistic than color photography. Monochrome images are not direct renditions of their subjects, but are abstractions from reality, representing colors in shades of grey. In computer terms, this is often called greyscale. Black-and-white photography is considered by some to add a more emotional touch to the subject, compared with the original colored photography.

Sepia and brown hued images are produced by certain photographic processes such as calotypes and albumen prints, or by the use of toning solutions which convert silver in the image to silver sulphide, imparting the brown or sepia tone. Selenium toner produces a blue-black or purple image, similarly by converting silver into more stable silver selenide.Cyanotypes used iron salts rather than silver salts to create blue and white hued images.

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