What is the difference between monochrome, black and white, and grayscale? The three terms are often used interchangeably, but there are technical differences.
A monochrome image consists of a single color of varying intensity against a neutral background. For example, night vision cameras use varying levels of green.
The definition of neutral background depends on the medium. On a computer monitor the background color is black. A red monochrome image will have black shadows and red highlights.
On paper the background color is white. A red monochrome image will have red shadows and white highlights.
A red and black image on paper is technically called duotone, because it requires two inks, red and black, to print the image.
Black and White
A black and white image is a type of monochrome image, one that uses black and white. The definition works for both computer monitors (levels of white on a black background) and paper prints (levels of black on a white background). All black and white images are monochrome, but not all monochrome images are black and white (see the red example above).
Grayscale has two meanings depending on context:
- A grayscale image is the same as a black and white image.
- Grayscale is a method of storing and representing black and white images on a computer. In Photoshop this is called a mode.
A mode in Photoshop is a way to store and represent color information. Modes have different origins and uses. For example, RGB originated in color film and TV. It’s basis is color filters used in film processes like Technicolor and color phosphors on CRTs. CMYK originated in the printing industry and represents colors of ink.
Grayscale Image vs Grayscale Mode
A grayscale image, like black and white film, only records the intensity, not the color of the image. In that sense grayscale images are the same as black and white images.