how to find out the indexed matrix of an image?

I find out color map and color data of an image.. but how find an index matrix from an color data

color data contains mxn pixels
color map contains RGB colors
index matrix consist of all the colors in an image it like 8,16,64... any number

[cdata cmap]=imread('');

[r c]=size(cmap);

colormap=cmap(1:r,:);    %store the colormap

position=colormap;

[Walter Roberson]

Do not use "colormap" as a variable name. "colormap" is the name of the function that changes the active color map.

[Anusha]

ok

Answer 1

[Walter Roberson]

In the above code, your variable "cdata" is the indexed matrix.

If you want the truecolor image implied by your "cdata" and "cmap", then you can use

ind2rgb(cdata, cmap)

[Anusha]

no need true color

cdata =index matrix is it?

I take an one image (8 color image)that consist cdata (2185x1575 unit8) values its too big matrix

but i want only number of color is presented in the matrix 8 color means only 8 value are presented.

it is possible

[Walter Roberson]

length(unique(YourArray(:)))

Like that? The number actually used?

Or do you mean

size(cmap, 1)

which is the number of entries in the assigned colormap even if some of the entries of the map are unused.