`contrast`

Returns a gray colormap that enhances the contrast of an image.

Category: Graphics > Formatting and Annotation

Syntax

cmap = contrast(X)

Returns a gray map sized like the current colormap.

cmap = contrast(X, m)

Returns a map with m gray levels.

Description

The map spreads the gray levels according to the distribution of the values in X, so that rare but important values are not squeezed into a narrow band of gray. Apply the result with colormap.

Input arguments

X: Image or numeric array of data values.
m: Number of colors.

Output arguments

cmap: m-by-3 gray colormap with equal RGB columns.

Example

A gray map for a matrix

c = contrast(magic(4), 8);
disp(size(c))
disp(isequal(c(:,1), c(:,2)))

Output

     8     3
   1

contrast