Greyscale

Greyscale images are also known as black-and-white or monochrome images and are composed exclusively of shades of grey, varying from black at the weakest intensity to white at the strongest. A greyscale image shows natural colour luminance with hue and saturation removed and so it carries only intensity information.

  • Greyscale images have many shades of grey in between black and white.
  • Greyscale images are distinct from one-bit bi-tonal black-and-white images which, in the context of computer imaging, are images with only two colours: black and white.
  • Greyscale images can be the result of measuring the intensity of light at each pixel against a selected wavelength or a weighted combination of wavelengths. In this case, the selected wavelengths can be from anywhere within the electromagnetic spectrum (e.g. infrared, visible light, ultraviolet.).
  • A colourimetric (or more specifically photometric) grayscale image is an image that has a defined greyscale colourspace, which maps the stored numeric sample values to the achromatic channel of a standard colourspace, which itself, is based on measured properties of human vision.