Solutions to selected questions.

4. C = 255 - C;

5. C(C<=128) = 0;  C(C>128) = 255;

6. C = C'  

7. l = length(C); C = C(l/4:3*l/4, l/4:3*l/4);

8. C = tril(C) + tril(C)' - diag(diag(C));

9. 

function [newC] = blur(C,n)

kernel = ones(2*n+1,2*n+1)/((2*n+1)*(2*n+1));

newC = conv2(kernel, C);

end

10. C1 = conv2(K1, C); C2 = conv2(K2, C); C = 255 - (abs(C1) + abs(C2));