how to use colorbar and colormap?

How to set the color at image same as color at color bar? How color map works?

Answer 1

[Chandra Kurniawan]

clear; clc;

I = imread('cameraman.tif');
imagesc(I); colormap(jet); colorbar;

[nur izzati]

Thank you,

and can I use colormap function for rgb image? because if I didnt convert rgb to gray image, the color in image is not parallel with color in color bar.

[Image Analyst]

You might be able to call it but it won't apply to any true color images residing on your figure. A colormap just doesn't make any sense for an image that is already in color, it only makes sense to apply a color to a gray level.