A white balance correction circuit for negative-to-positive conversion of television signals includes an imaging device for picking up a negative picture to develop video signals which are respectively indicative of three separated colors. The three separated color signals are processed by three processing circuits which are assigned in one-to-one correspondence thereto. An encoder circuit combines output signals of the respective processing circuits to provide a color composite video signal representative of a positive picture associated with the negative picture. Each of the processing circuits comprises an inversion circuit for inverting one of the three separated video signals associated therewith, and a clamp circuit for maintaining extreme values of the video signal at a first predetermined value, whereby a positive picture having an adjusted luminance is reproduced.