Page 207 - MATLAB Recipes for Earth Sciences

202 8 Image Processing

Fig. 8.1 RGB true color image contained in the fi le unconform.jpg. After decompressing and

reading the JPEG file into a 729x713x3 array, MATLAB interprets and displays the RGB
composite using the function imshow. See detailed description of the image on the NASA
TERRA-ASTER webpage http://asterweb.jpl.nasa.gov. Original image courtesy of NASA/
GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team.

data array. The colormap array is an m-by-3 array containing fl oating-point

values between 0 and 1. Each column specifies the intensity of the colors
red, green and blue. The data array is an x-by-y array containing integer ele-
ments corresponding to the lines m of the colormap array, i.e., the specifi c
RGB representation of a certain color. Let us transfer the above RGB image
into an indexed image. The colormap of the image should contain 16 differ-
ent colors.
[x,map]=rgb2ind(unconform1,16);