## In Bicubic Interpolation values of coefficient ai and bj for 2x come [0.3125 0.9375 -0.3125 0.0625] and [0 1 0 0]. So if pixel matrix P11 to P44 be [235 200 30 200; 235 230 23 200; 20 20 25 20; 235 225 10 235] then output value exceeds the limit of gray values (0-255).

I am not clear about your question