PURPOSE: To allow coloring of letter/pattern image produced by a computer, etc., by introducing an external burst signal extracted from a image signal when the first complex image signal inputted from the outside is color, and introducing an internal burst signal when said signal is black and white.

CONSTITUTION: When a color complex image signal arrives at an input terminal 1, the signal is introduced to a synchronizing signal input line A of a composite circuit 14 through switches SW3 and SW1. On the other hand, a color burst signal of the complex image signal is inputted to a carrier chrominance component generation circuit 4, passing through a burst extraction circuit 3 and a changeover switch SW4, and is introduced to a chroma signal forming circuit 12. When an arrival signal of the input terminal 1 becomes a black and white image signal, an output of a frequency dividing circuit 7 is introduced to the carrier chrominance component generation circuit 4 through the SW4, formed into a continued 3.58MHz signal and introduced to the chroma signal forming circuit 12 through the SW2.