Abstract: In a polygon circuit for input signal level compression in a signal processing circuit in, for example, a color television camera or the like, a first current proportional to the difference between an input signal voltage Vin and a reference voltage Vref is provided, and a clip circuit clips the input signal voltage Vin at a break-point setting voltage Va. A second current proportional to the difference between the output voltage of said clip circuit and the break-point setting voltage is produced, and addition or subtraction is performed on the first current and the second current to output a voltage signal proportional to the sum or the difference.