% Global constants - main directory, picture paths, etc.
MAIN_DIR = 'http://www.vision.caltech.edu/Outreach/CSUN-Spring2005/Pictures/urine_database/';
CLASSES = {'IRIS-BACT', 'IRIS-RBC', 'IRIS-WBC'};
FILE_EXTENSION = '.jpg';
NUM_OF_PICTURES = 10;
NUM_OF_CLASSES = length(CLASSES);

figure(1); clf;
% Essentially, we first iterate over the classes, then iterate over
% the elements in each class.
for i = 1:NUM_OF_CLASSES
     for j = 1:NUM_OF_PICTURES
         % Generate the name of each file dynamically (first trim off any
         % trailing spaces!).
         class = CLASSES{i};
         file_name = [MAIN_DIR class '/' num2str(j) FILE_EXTENSION];
         the_image = imread(file_name);
         % Split the figure window into 10 rows, 3 columns.
         subplot(10, 3, i);
         % Include titles over each column.
         title(class);
         % Display images.
         subplot(10, 3, 3*(j - 1) + i);
         imagesc(the_image);
         colormap(gray);
         % Make it look all pretty by removing the ugly, unnecessary tick
         % marks.
         axis off;
         axis image;
     end
end