sess1

clear
load filelist
filename = char(files{1});
rgb1 = im2double(imread(filename));
imshow(imresize(rgb1,0.25,'bilinear'));

close all
for m=1:14
    subplot(4,4,m)
    filename = char(files{m});
    rgb =im2double(imread(filename));
    s = imresize(rgb,0.25,'bilinear');
    imshow(s);
    title(sprintf('image %d',m));
end

close all
for m=1:4
    subplot(2,2,m)
    file1 = char(files{m});
    file2 = char(files{m+1});
    g1 = rgb2gray(im2double(imread(file1)));
    g2 = rgb2gray(im2double(imread(file2)));
    d = imresize(g1 - g2,0.25,'bilinear');
    imshow((d+1)/2);
    title(sprintf('difference image %d from image %d',m+1,m));
end

close
m=1;
file1 = char(files{m});
file2 = char(files{m+1});

g1 = rgb2gray(im2double(imread(file1)));
g2 = rgb2gray(im2double(imread(file2)));
d = g1-g2;
imhist((d+1)/2);

bins = imhist((d+1)/2);
x = linspace(-1,1,256);
plot(x,bins);
grid
xlabel('difference');
ylabel('count');

cd = cumsum(bins);
cd = cd/cd(end);
plot(x,cd,'k','LineWidth',2);
grid;
axis([-0.2 0.2 0 1]);
xlabel('difference');
ylabel('fraction exceeding');

ndx = find(bins>3);
plot(x(ndx),log10(bins(ndx)));
grid;
xlabel('difference');
ylabel('log count');

bins = imhist(abs(d));
cd = cumsum(bins);
cd = cd/cd(end);
x = linspace(0,1,256);
plot(x,cd,'k','LineWidth',2);
grid;
axis([0 0.2 0 1]);
xlabel('difference');
ylabel('fraction exceeding');

frac = interp1(x,cd,0.1);
fprintf('%g%% of pixels exceed 0.1\n',100*(1-frac));

frac = 0.95;
[cd ndx] = unique(cd);
x = x(ndx);
thres = interp1(cd,x,frac);
fprintf('frac %g value %g\n',frac,thres);

1.29538% of pixels exceed 0.1
frac 0.95 value 0.0223651

thres = 0.1;
bw = abs(d)>thres;
sz = size(bw);
frc = sum(bw(:))/prod(sz);
fprintf('%g%% of pixel exceed %g\n',frc*100,thres);
imshow(imresize(bw,0.5));

1.32322% of pixel exceed 0.1

Published with MATLAB® 7.13