clear;
pollen = imread('Fig3.10(b).jpg');
u = double(pollen);
[nx ny] = size(u)
nshades = 256;

r1 = 80;  s1 = 10;   % Transformation by piecewise linear function.
r2 = 140; s2 = 245;
for i = 1:nx
    for j = 1:ny
        if (u(i,j)< r1)
            uspread(i,j) = ((s1-0)/(r1-0))*u(i,j)
        end
        if ((u(i,j)>=r1) & (u(i,j)<= r2))
            uspread(i,j) = ((s2 - s1)/(r2 - r1))*(u(i,j) - r1)+ s1;
        end
        if (u(i,j)>r2)
            uspread(i,j) = ((255 - s2)/(255 - r2))*(u(i,j) - r2) + s2;
        end
    end
end
pollenspread = uint8(uspread);
imwrite(pollenspread, 'pollenspread.jpg');

u = double(pollenspread);     % Sharpen the image.
coeff = .1;
for k = 1:1         
    for j = 2:ny-1
        for i = 2:nx-1
            newu(i,j) = u(i,j) - coeff*(u(i-1,j) -2*u(i,j) + u(i+1,j))...
                               - coeff*(u(i,j-1) -2*u(i,j) + u(i,j+1));
        end                  
    end
    u = newu;
end
pollensharpenmat = uint8(u);
imwrite(pollensharpenmat, 'pollensharpen.jpg');