How to Split the Matlab Jet Color Table to RGB

MATLAB color tables map values to colors.

MATLAB is a software package produced by MathWorks that enables users to build upon a large library of functions for technical analysis and presentation. In the production of color figures, MATLAB provides a set of colormaps to convert between data values and colors in figures. Accessing the color values in a MATLAB colormap is simple to do through both the user interface and command line.

Instructions

1. Create a jet color table with a specified number of values using the jet() function with an integer input. The default colormap for MATLAB is jet(64). The my_cmap variable is a 64x3 array containing red, green, blue color values.

   my_cmap = jet(64);
   my_other_cmap = jet(128);

2. Access the RGB values of a particular value in the jet colormap by accessing the stored colormap array. Accessing my_cmap(32,:) returns the RGB value [0.5 1.0 0.5]. MATLAB RGB color values are floating point numbers ranging between 0 and 1.0.

3. Edit the specifics of the stored colormap by manipulating the RGB values of the stored colormap array.

4. Apply the altered colormap using the colormap() function. The first example applies the colormap to the current figure while the second example targets a specific graph by passing the axis handle.

   colormap(my_cmap);
   colormap(axes_handle, my_cmap);

5. Edit the currently selected colormap by calling the colormapeditor() function from the MATLAB command line.

Tips & Warnings

• The names of built-in MATLAB colormaps are jet, HSV, hot, cool, spring, summer, autumn, winter, gray, bone, copper, pink and lines.

References

• MATLAB Documentation: colormap
• MATLAB Documentation: colormapeditor