JP2773848B2 - Television signal system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a letterbox television signal system, and more particularly to a television signal system in which only a non-image portion is not compensated for luminance detail in a dark portion of an image to improve image quality. It relates to a signaling system.

[0002]

2. Description of the Related Art Recently, various EDTV systems which achieve a wide aspect ratio while maintaining compatibility with the current NTSC system have been proposed. This is the so-called second generation EDTV system. Among them, as one method for achieving a wide aspect, there is a letter box method in which a non-picture portion is provided at the upper and lower portions of an NTSC screen.

On the other hand, the first-generation EDTV system has already been started as a current clear-vision broadcast service, and is constituted by image quality improvement techniques on both the transmission side and the receiver side.

The S1 system is one of the first-generation image quality improvement techniques described above. In order to compensate for a decrease in the reproducibility of the luminance detail in the dark part of the image in the current receiver, the detail component increases in the dark part. In addition, the high-frequency component of the luminance is compensated on the transmission side.

FIG. 5 shows a configuration example of the S1 system. As shown in the figure, in the S1 system, an adaptive emphasis circuit 51 is configured for the luminance signal 50, and an S1 emphasis output 52 is obtained. In the figure, the configuration of the adaptive emphasis circuit 51 surrounded by a broken line will be described below. Here, an adaptive emphasis circuit is configured based on information on the brightness of the image. First, the input luminance signal 50 is led to an inverting amplifier 54 via a low-pass filter 53 in order to extract the brightness information of the image from the input luminance signal. Low frequency component 5
7 is extracted.

On the other hand, from the input luminance signal 50, a high-frequency emphasis component 58 which is also applied to an emphasis circuit 56 for compensating for a high-luminance component is extracted. Further, the inverted low-frequency component 57 (brightness information) and the high-frequency emphasis component 58 are respectively applied to a multiplier 59 at the next stage, and an adaptive emphasis component 60 is output as a multiplied output. That is, an adaptive emphasis output is obtained for the brightness information. The adaptive emphasis component 60 obtained here is finally added to the current signal (luminance signal 50) by the adder 61.
And an S1 emphasis output 52 is output as a final output.

[0007]

However, in the S1 system having the above-described configuration, since the emphasis of S1 always operates on the input signal, the non-picture portion of the letterbox video signal is compensated. The analog or digital data multiplexed at a low level is reproduced in detail. Therefore, when an image is received by the current image receiver, there is a problem that the image is displayed in a state where the interference of the black portion of the non-image has increased.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a letterbox television signal method for providing a non-picture part at the top and bottom of a television screen to widen the picture screen. Emphasis means for performing compensation by a luminance detail compensation method for a dark part (S1 method of the first generation EDTV), and a non-picture part gate pulse generating means for generating a gate pulse indicating a non-picture part located above and below an image And switching means for shutting off the emphasis means on the transmission side in synchronization with the gate pulse so as to cut off the compensation by the emphasis means only in the non-picture part. The configuration is such that the blocked letterbox video signal is transmitted.

[0009]

According to the above arrangement, a gate pulse is generated in synchronism with the non-image portion, and the S1 emphasis circuit is turned ON / OFF by the gate pulse, so that a letter box television signal is obtained in which only the non-image portion does not receive S1 emphasis. be able to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in FIGS. FIG. 1 is a system diagram showing an overall configuration of a system according to the present invention. In the drawing, a circuit means 10 surrounded by a broken line is a circuit which is a feature of the present invention, and includes the following two circuit blocks. One is a non-picture part gate pulse generating circuit 11 for generating a non-picture part gate pulse 13 indicating a non-picture part (hatched part in FIG. 3) in the letterbox image, and the other is synchronous with the gate pulse 13. Then, the S1 emphasis circuit 14 is turned off in the non-image portion, and the S1 emphasis circuit 14 is turned on and off in the video portion other than the non-image portion so that the S1 emphasis circuit 14 is turned on.
It is.

Hereinafter, based on FIGS. 2 and 4, the non-picture part gate pulse generation circuit 11 and the S1 emphasis circuit ON / O
The operation of the FF switch 12 will be described. FIG. 2 is a block diagram showing a configuration of the non-image portion gate pulse generation circuit 11. FIG. 4 is a timing chart illustrating the circuit operation of FIG. As shown in FIG. 3, if the non-picture part of the letterbox type screen is the upper and lower ends of the lines k-1 and m-n, the non-picture part gates are the lines k-1 and m-n. You only have to open in the part.

As shown in FIG. 12, the H clock (b) is counted by H counters 21, 22, 23 and 24 to detect the timing of lines k, l, m and n (d, e,
f, g) and lines k and m are used as set pulses (h) of the subsequent SR latch 25, and lines l and n are used as reset pulses (i). j).

The non-image portion gate pulse 13 (j) is supplied to S1
Used as a switching control signal for the emphasis circuit ON / OFF switch 12. As shown in FIG. 4 (j), the non-image part gate pulse 13 is used in FIG.
The portions corresponding to m to n are high, and the other portions are low, and the switch 12 is turned off in the non-image portion (high).
F, operates to turn on the switch 12 in other parts.

Therefore, by these circuit operations, S1 emphasis is turned off in the non-image area,
A video signal of the letter box system in which S1 emphasis is not applied only to the non-image portion is output.

[0015]

According to the present invention having the above-described configuration, it is possible to reduce the interference of the black portion that occurs when a current receiver receives a letterbox video signal, thereby improving the image quality.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration example of a non-image portion gate pulse generation circuit of the present invention.

FIG. 3 is a view for explaining a state of a screen when a current NTSC receiver receives a signal of the letter box system.

FIG. 4 is a timing chart illustrating the operation of the non-image portion gate pulse generation circuit according to the present invention.

FIG. 5 is a configuration diagram of a conventional example.

[Explanation of symbols]

 11 Non-image part gate pulse generation circuit 12 S1 emphasis circuit ON-OFF switch 14 S1 emphasis circuit

Claims (1)

(57) [Claims] In a letter box television signal system in which a non-image part is provided at an upper and lower part of a television screen to widen a video screen, a luminance detail compensation method for an image dark part (first generation extended definition TV (EDTV))
Emphasis means for performing compensation by the S1 method, a non-picture part gate pulse generating means for generating a gate pulse indicating a non-picture part located above and below an image, and only the non-picture part by the emphasis means. Switching means for shutting off the emphasis means on the transmitting side in synchronization with the gate pulse so as to cut off the compensation, and transmitting a letterbox video signal in which the compensation by the S1 system emphasis means is cut off only in the non-image portion. A television signal system, characterized in that: