How do I create a colormap?

I've been having problems creating a colormap in the Staff version of Matlab (Matlab R2013b). I want to create a colormap of the type "jet", so I typed in the Command Window:

myColorMap = jet(256);   
colormap(myColorMap);  
colorbar

However, when I press enter, a window (called "Figure 1") pops up with a colormap, but with no picture in it. I've imported the picture (filename: Picture1Edit.jpg) into the program, I can see it in the sidebar "Current folder" left of my Command Window, so I know it's definetely there. Could anyone help me creating this colormap?

Answer 1

[Bjorn Gustavsson]

That's the way you create a colormap. The colorbar command forces the creation of an axes, that forces the creation of a figure (unless the figure and an axes already exists). To display the image you'll have to use some of the image display-functions: imshow, image, imagesc; or even surf/pcolor if you want some more complex warping of the image. Then you can put a colorbar on the side of those displays.

HTH

Answer 2

[Image Analyst]

Try this:

% Get full file name.
baseFileName = 'Picture1Edit.jpg';
folder = pwd; % Current folder
% Display if it exists, warn and exit if not.
if exist(fullFileName, 'file')
  grayImage = imread(fullFileName);
  imshow(grayImage);
else
  message = sprintf('Error: %s not found', fullFileName);
  uiwait(warndlg(message));
  return;
end
% Apply colormap.
myColorMap = jet(256);   
colormap(myColorMap);  
colorbar