In a television display apparatus comprising,
- first television signal receiving means for receiving a first television signal of a first color television standard system,
- second television signal receiving means for receiving a second television signal of a second color television standard system,
- said first television signal including at least a horizontal synchronizing signal and a vertical synchronizing signal of the standard type defined by the first color television standard system,
- said second television signal including a horizontal synchronizing signal, a vertical synchronizing signal, a color burst signal, a video signal, a chrominance signal of the standard type defined by the second color television standard system, and
- picture display means coupled to said first and second television signal receiving means for displaying pictures of said first and second television signals,
- a method of displaying a picture of said first television signal in a large image area on the screen of said picture display means, and displaying a picture of the second television signal in a small image region within said large image area by locally substituting for the picture of said first television signal, so that a composite picture having the picture of said second television signal is nested in the picture of the first television signal on the screen of said picture display means, comprises the steps of:
- generating a clock signal in synchronism with the color burst signal included in said second television signal and having a frequency of L/K times (K.ltoreq.L, K and L are natural numbers) the frequency of the color subcarrier,
- generating a plurality of writing signal trains by shifting the phase of the clock signal generated by said step of generating a clock signal by a predetermined amount of the clock cycle selected so as to correct the phase shifting between the cycle of said second clock signal and the cycle of the horizontal scanning of said second television signal, for every 1 horizontal period of the second television signal,
- generating a reading clock signal associated with the horizontal synchronizing signal and the vertical synchronizing signal included in said first television signal,
- converting the number of scanning lines of the second television signal to the number in which the scanning lines of the picture of the first television signal in the large image area is included within the height of the small image area, in accordance with the ratio of the height of the large image area to the height of the small image area,
- writing into the field memory the second video signal generated in said step of converting the second television signal scanning line number in response to the cycle of the writing clock signal generated in said step of generating a plurality of writing signal trains,
- reading the second video signal written into the field memory in said step of writing the second video signal in response to the cycle of the generated reading clock signal, and
- substituting the video signal associated with the second television signal read out in said step of reading the second video signal for one portion of the video signal included in said first television signal.