cmpermute (Image Processing Toolbox User's Guide)

Image Processing Toolbox User's Guide

Rearrange the colors in a colormap

Syntax

[Y,newmap] = cmpermute(X,map)
[Y,newmap] = cmpermute(X,map,index)

Description

[Y,newmap] = cmpermute(X,map) randomly reorders the colors in map to produce a new colormap newmap. The cmpermute function also modifies the values in X to maintain correspondence between the indices and the colormap, and returns the result in Y. The image Y and associated colormap newmap produce the same image as X and map.

[Y,newmap] = cmpermute(X,map,index) uses an ordering matrix (such as the second output of sort) to define the order of colors in the new colormap.

Class Support

The input image X can be of class uint8 or double. Y is returned as an array of the same class as X.

Example

To arrange a colormap in order by luminance, use

ntsc = rgb2ntsc(map);
[dum,index] = sort(ntsc(:,1));
[Y,newmap] = cmpermute(X,map,index);

This example orders a colormap by luminance.

load trees
ntsc = rgb2ntsc(map);
[dum,index] = sort(ntsc(:,1));
[Y,newmap] = cmpermute(X,map,index);
figure, imshow(X,map)
figure, imshow(Y,newmap)

See Also

randperm, sort in the MATLAB Function Reference

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