color map and color data

If we change a color map of an image, the color data will automatically updated or not?

ADD

for example

[cdata cmap]=imread('');

[r c]=size(cmap);

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

position=colormap;

i want code for if cmap i.e)colormap changes the cdata also automatically changes

Answer 1

[Vivek Selvam]

Unless you give the modified color data to colormap() it would not be updated.

For example:

load flujet;
image(X);                      % default colormap 'jet'
c      = colormap(hsv(128));   % update
c(c>0) = 1;                    % no update
colormap(c);                   % update

[Anusha]

look ADD part at the question...

Answer 2

[Walter Roberson]

cdata does not update when a colormap changes. When you are using pseudocoloring, cdata remains the same and is used to index into the active color map, with you being able to activate a new map.

For example,

   cm = colormap(pink(128));
   image(rand(64,64));
   colormap(cm);
   pause(10);
   colormap(flipud(cm));
   pause(10);

The cdata remains the same but what is painted changes when colormap() is called.