Function File: isgray (img)

Return true if img is a grayscale image.

A variable can be considered a grayscale image if it is a non-sparse, real array of size MxNx1xK, and:

• of floating point class with values in the [0 1] range or NaN;
• of class uint8, uint16, or int16.

Note: despite their suggestive names, the functions isbw, isgray, isind, and isrgb, are ambiguous since it is not always possible to distinguish between those image types. For example: an uint8 matrix can be both a grayscale and indexed image; a grayscale image may have values outside the range [0 1]. They are good to dismiss input as an invalid image type, but not for identification.

See also: gray2ind, isbw, isind, isrgb.

Package: image