how to find map matrix to an 3D image as in load function?

in this code

load wbarb;

the output be the image 'X' and the map of it.

I want to find the map to my image so I wrote a cod as:

[X,map] = imread('pears.png');

the output be the image 'X' but the map be like this []

so what is the right way to find 'map' in 3 columns?

[Rasha]

 I found this code and I think it's what I looking for
[X,map] = cmunique(RGB);