Image Types in the Toolbox :: Introduction (Image Processing Toolbox User's Guide)

Image Processing Toolbox User's Guide

Image Types in the Toolbox

The Image Processing Toolbox defines four basic types of images, summarized in the following table. These image types determine the way MATLAB interprets data matrix elements as pixel colors. The sections that follow provide more information about each image type. See also Converting Between Image Types.

Image Type
Interpretation

Binary
Logical array containing only 0's and 1's, interpreted as black and white, respectively. Also known as a bilevel image.

Indexed
Array of class logical, uint8, uint16, single, or double whose pixel values are direct indices into a colormap. The colormap is an m-by-3 array of class double. Also known as a pseudocolor image.
Note: For single or double arrays, integer values range from [1, p]. For logical, uint8, or uint16 arrays, values range from [0, p-1]

Grayscale
Array of class uint8, uint16, int16, single, or double whose pixel values specify intensity values. Also known as a intensity image
Note: For single or double arrays, values range from [0, 1]. For uint8, values range from [0,255]. For uint16, values range from [0, 65535]. For int16, values range from [-32768, 32767].

Truecolor
m-by-n-by-3 array of class uint8, uint16, single, or double whose pixel values specify intensity values. Also known as an RGB image.
Note: For single or double arrays, values range from [0, 1]. For uint8, values range from [0, 255]. For uint16, values range from [0, 65535].

Image Type	Interpretation
Binary	`Logical` array containing only 0's and 1's, interpreted as black and white, respectively. Also known as a bilevel image.
Indexed	Array of class `logical`, `uint8`, `uint16`, `single`, or `double` whose pixel values are direct indices into a colormap. The colormap is an m-by-3 array of class `double`. Also known as a pseudocolor image. Note: For `single` or `double` arrays, integer values range from [1, p]. For `logical`, `uint8`, or `uint16` arrays, values range from [0, p-1]
Grayscale	Array of class `uint8`, `uint16`, `int16`, `single`, or `double` whose pixel values specify intensity values. Also known as a intensity image Note: For `single` or `double` arrays, values range from [0, 1]. For `uint8`, values range from [0,255]. For `uint16`, values range from [0, 65535]. For `int16`, values range from [-32768, 32767].
Truecolor	m-by-n-by-3 array of class `uint8`, `uint16`, `single`, or `double` whose pixel values specify intensity values. Also known as an RGB image. Note: For `single` or `double` arrays, values range from [0, 1]. For `uint8`, values range from [0, 255]. For uint16, values range from [0, 65535].

Images in MATLAB and the Image Processing Toolbox Binary Images