Page 145 - Computational Colour Science Using MATLAB

132 CHARACTERIZATION OF CAMERAS

else
plotgraphs = strcmp(’on’,graphs);
end

% fit the low-order polynomials
[pr1,sr1]=polyfit(r,ref,3);
[pg1,sg1]=polyfit(g,ref,3);
[pb1,sb1]=polyfit(b,ref,3);

% plot graphs if the plotgraphs variable is set
if (plotgraphs)
figure

subplot(3,2,1)
plot(r,ref,’ko’);
[pr1,sr1]=polyfit(r,ref,3);
x = linspace(0,1,11);
y = polyval(pr1,x);
hold on
plot(x,y,’k-’);
ylabel(’Y’)
xlabel(’R channel’);
axis([0 1 0 1])
subplot(3,2,2)
py = polyval(pr1,r);
plot(ref,py,’ko’);
hold on
plot([0 1], [0 1], ’k-’);
axis([0 1 0 1])
disp(255*py’)

subplot(3,2,3)
plot(g,ref,’ko’);
x = linspace(0,1,11);
y = polyval(pg1,x);
hold on
plot(x,y,’k-’);
ylabel(’Y’)
xlabel(’G channel’);
axis([0 1 0 1])
subplot(3,2,4)
py = polyval(pg1,g);