ad an image, and downsample to a size appropriate for the machine speed.
oim = pgmRead('einstein.pgm');
tic; corrDn(oim,[1 1; 1 1]/4,'reflect1',[2 2]); time = toc;
imSubSample = min(max(floor(log2(time)/2+3),0),2);
im = blurDn(oim, imSubSample,'qmf9');
clear oim;

%%% ShowIm: 
%% 3 types of automatic graylevel scaling, 2 types of automatic
%% sizing, with or without title and Range information.
help showIm
clf; showIm(im,'auto1','auto','Al')
clf; showIm('im','auto2')
clf; showIm(im,'auto3',2)

%%% Statistic