JPH03207187A - Television signal transmission system - Google Patents

Abstract

PURPOSE:To prevent the upper and lower parts of an image from becoming hard to view by dividing the signal of a side panel part with frequency and arranging a low frequency component which is visually easy to see outside the image. CONSTITUTION:An image signal 50 whose longitudinal/lateral ratio is 3:5 is inputted and a segmenting circuit 4 segments the center part of the image from the image signal 50; and a filter circuit 1 divides the side panel part into two components, i.e., a low frequency part component 51 and a high frequency component 52 by aiming at, for example, the horizontal frequency component of the image. The low frequency component 53 and high frequency component 54 which are rearranged and compressed on the time base by rearranging circuits 2 and 3 are inputted to a selecting circuit 5 together with a center part image signal 55 and transmitted to image reception side. Consequently, the low frequency component 53 which is visually easy to see is hidden behind overscanning carried out by a television image receiver and not displayed as an image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a television signal transmission system.

(Prior Art) The aspect ratio of the current standard television signal is 3:4. An image signal with the same resolution, the same number of scanning lines, and a horizontally wider aspect ratio than 3 = 4 as the current standard television signal can be reproduced as an original image within the transmission band of the current standard television signal and even on current television receivers. As one method for transmitting images so as to make it possible to reproduce images in the central part of the screen, a method has been devised as described in the Technical Report TEBS8843 "Experimental System for Wide Television" of the Television Society of Japan. That is, first, the image shown in FIG. 5(a), which has an aspect ratio wider than 3:4 in the horizontal direction, is divided into a central portion (2) and side panel portions (2) and (2) at both ends thereof. The part marked (■) is the part played on current television receivers. An image signal with an aspect ratio wider than 3:4 is scanned at a higher speed than the current standard television signal, corresponding to the wider aspect ratio. Therefore,
The part (3) is expanded on the time axis and inserted into the part (2) of the current standard television signal with an aspect ratio of 3:4 as shown in FIG. 5(b). Further, the side panel portions ■ and ■ in FIG. 5(a) are rearranged and fitted into the areas ■ and ■ in FIG. 5(b). When the image signals rearranged in this manner are received by a dedicated receiver, a wide aspect image with N scanning lines is restored. As shown in Figure 5, α scanning lines are used to transmit the side panel portions ■ and ■, so the effective number of scanning lines is α fewer than the current television signal. ing.

(Problem to be solved by the invention) In the above-mentioned conventional technology, compared to the current television signal, α
Only the book will have fewer effective scanning lines.

Therefore, in current television receivers, signals that should originally be decoded as side panels are visible in the upper and lower portions of the image. On the other hand, many current television receivers do not display the entire transmitted image, but instead use overscanning to display only a few percent of the top, bottom, left and right sides of the image.

However, in the conventional technology, in order to widen the aspect ratio to a certain extent in the horizontal direction, it is impossible to multiplex all the signals of the side panel part in the area that becomes invisible due to overscanning, and the signals of the side panel part are It had the disadvantage that it looked like a part.

SUMMARY OF THE INVENTION An object of the present invention is to alleviate the drawbacks of the conventional system, and to provide a television signal transmission system in which signals in the side panel portion of the current television receiver are difficult to see in the upper and lower portions of the image.

(Means for Solving the Problems) The television signal transmission system of the present invention transmits a wide aspect image signal having an aspect ratio wider in the horizontal direction than a reference aspect ratio. In this method, the wide aspect image signal is divided into a central part of the image and side panel parts at both left and right ends of the image, and the signal of the side panel part is transmitted above and below the signal of the central part of the image. In a method of rearranging and transmitting signals in the side panel portion, when rearranging the signals in the side panel portion above and below the signals in the center portion of the image, the signals in the side panel portion are frequency-divided to express low frequency components. They are rearranged and transmitted so that they are placed on the outside.

(Function) The present invention relates to a method for transmitting a side panel portion of a wide aspect image signal having an aspect ratio wider in the horizontal direction than a reference aspect ratio.

In a general image, when an image signal is frequency-divided, the low frequency components often have more signal energy than the high frequency components. Therefore, the low frequency components of an image are visually easier to see than the high frequency components. In the present invention, this property is used to divide the signals of the side panel part into frequencies when rearranging the signals of the side panel part to the top and bottom of the image, so that the low frequencies that are easier to see visually are placed further outside the image. It is arranged so that In other words, as shown in Fig. 1, a certain amount of low frequency that is easily visible is placed in the areas ■ and ■ that are overscanned by current television receivers, and the areas that are visible above and below the image with current television receivers are placed. In (2) and (2), some high frequency waves that are relatively difficult to see visually are placed. Therefore, when viewing an image on a current television receiver, it is difficult to see that the signals from the side panel portion are multiplexed on the upper and lower portions of the image.

(Example) Next, an example of the present invention will be described using FIGS. 1 to 5. As an example, we will input an image signal with an aspect ratio of 3:5, rearrange the signals for the side panel portion, and multiplex the time axis above and below the television screen to fit within the transmission band of the current NTSC television signal. A case will be described in which the central part of the original image is transmitted so that it can be reproduced even on a current NTSC television receiver.

It is also assumed that the input image signal has the same pixel density (resolution) as the current NTSC signal, so the aspect ratio is from 3=4 to 3:
5, the signal band has become wider, and is 5/4 times (5/4) the signal band of the current NTSC signal, 4.2MHz.
．． 25MHz) signal band. Furthermore, as shown in FIG. 5(a), the input image is
As an example, it is assumed that the number of effective scanning lines N=432 and the side panel transmission scanning line α=51. At this time, the number of pixels per scanning line is calculated based on the number of pixels when the NT8C signal is sampled at a sampling frequency (approximately 14.3MHz) that is four times the color subcarrier frequency (fsc). The number of pixels in the center part ■ is 756 pixels (the effective area of the NTSC signal is approximately 0.83 times the period of one scanning line), and the number of pixels in the side panel parts ■ and ■ is 88 pixels in total.
As a result, a field image signal having an aspect ratio of 3:5 and having 432 effective scanning lines and 844 effective pixels is transmitted.

Further, as an example, a case where the rearrangement process is performed in units of frames will be described.

FIG. 2 is a block diagram showing the basic structure of an embodiment of the present invention.

First, an image signal 50 having an aspect ratio of 3:5 is input. The image signal 50 is extracted from the image signal 50 by the cutting circuit 4. The central portion (2) is cut out, expanded by 5/4 times on the time axis so as to fit within the transmission band of the current NTSC television signal, and output as the central image signal 55.

Further, regarding the side panel portions (1) and (2), the filter circuit 1 focuses on, for example, the frequency in the horizontal direction of the image and divides it into two components: a low frequency component 51 and a high frequency component 52. The frequency division here is the image signal 50
The signal band of 5.25 MHz is exactly halved, and the high frequency component 52 is reduced by 5.2 MHz after frequency division.
The signal is frequency-shifted by 5/2 MHz. The low frequency component 51 and the high frequency component 52 are input to rearranging circuits 2 and 3, respectively, where they are rearranged and compressed on the time axis as shown in FIG.
Output as 4. That is, in Fig. 3, NX2 signals of low (high) frequency L1 to LN, R■ to ~ for each scanning line are processed using m signals in each scanning line and a/2 scanning lines. Sort by. However, considering that the frequency is divided into two parts, it is possible to compress the time axis to 1/2 and transmit it, so the number of pixels corresponding to the effective image period of the current NTSC signal is 756. It is possible to transmit twice the number of pixels in one scanning line. In the case of this embodiment, if N=432, m=34, and α=51, mX44=748X2 pixels are used per scanning line (N
If m)≦(a/2)=25.5 scanning lines are used, low (
All high) frequency components will be transmitted. That is, 25.
If 5×2=51 scanning lines are used, all the signals of the side panel portion can be transmitted. In addition, low frequency component 5
Similarly to the center image signal 55, the high frequency component 54 and the center image signal 55 are signals expanded by 5/4 on the time axis so as to fit within the transmission band of the current NTSC television signal. The low frequency components 53 and high frequency components 54 that have been rearranged and compressed on the time axis in the rearrangement circuits 2 and 3 as described above are input to the selection circuit 5 together with the center image signal 55, and are input to the first selection circuit 5. The signal is transmitted to the image receiving side as a transmission signal 56 in the format shown in the figure. That is, the center image signal 55 is
The low frequency component 53 is placed in the area of ■ and [stock], and the high frequency component 54 is placed in the area of ■ and ■ for transmission. At this time, the visually easily visible low frequency part 53 is transmitted using 25.5 scanning lines of ■ and
483 (approximately 4%), so it is not displayed as a placed image.

The television signal processed in the above manner is processed in a dedicated receiver in the opposite manner to the processing on the transmission side described above, and an image with an aspect ratio of 3:5 is reproduced.

Further, the embodiment shown in FIG. 2 can also be realized by the configuration shown in FIG. 4. That is, an image signal 50 is input, and a center image signal 55 is obtained in the same manner as in the embodiment shown in FIG. Similarly to the rearrangement circuits 2 and 3 in FIG. 2, the storage/rearrangement circuit 6 rearranges the signals in the side panel portion, compresses them on the time axis, and outputs a rearrangement signal 57. At this point, the reordering signal 57 is (4.2 x 2
) MHz signal band. Sorting signal 5
7 is memory. The signals are stored in the rearrangement circuit 6, and the same signal is output twice. In the filter circuit 7, among the two same signals of the rearrangement signal 57, one signal is a low frequency component (DC to 4.2 MHz), and the latter one is a high frequency component (4.2 MHz to 8.2 MHz). 4MHz) filter signal 5
Output as 8. It is assumed that the high frequency component of this filter signal 58 has been frequency shifted to a lower frequency band by 4.2 MHz. Filter signal 58 and center image signal 55
is selected by the selection circuit 8 and outputted as a transmission signal 56 in the format shown in FIG. Note that the storage and rearrangement circuit 6 needs to output a rearrangement signal 57 in accordance with the format shown in FIG.

In addition, in this example, focusing on a certain frequency in the horizontal direction, 2
Although the frequency is divided into individual components, the frequency may be divided by focusing on a certain frequency in the vertical direction, or the frequency may be divided into three or more components.

Further, the aspect ratio may not be 3:5, and the number of effective scanning lines and the format of the television signal may be different. Further, image signals having different resolutions, effective numbers of scanning lines, or numbers of scanning lines may be used as the original signals.

Further, the rearrangement process may be performed not for each frame but for each field.

Furthermore, the number of frequency divisions and the arrangement may be changed for each field. According to this aspect, when the signal according to the present invention is received by a current receiver, the signal in the side panel portion will appear more like noise in the upper and lower portions of the image, and the viewer will not be able to see the side panel portion. This will make the image easier to view. Since the device configuration according to this aspect is clear from the above explanation, detailed explanation will be omitted.

(Effects of the Invention) As described above, according to the present invention, when transmitting an image signal with a horizontally wide aspect ratio while maintaining compatibility with current television signals, it is possible to This makes it possible to make it difficult to see the signals on the side panel that were previously visible.

[Brief explanation of drawings]

1 and 3 are diagrams showing a method of rearranging signals in the side panel portion in an embodiment of the present invention, and FIGS. 2 and 4 are diagrams showing the structure of an embodiment of the present invention. Figure 5 (a)
, (b) are explanatory diagrams of the conventional method. In the figure, 1, 7...filter circuit, 2, 3...
Sorting circuit, 4... Cutting circuit, 5, 8... Selection circuit, 6... Storage/sorting circuit.

Claims (1)

[Claims] A method for transmitting a wide aspect image signal having an aspect ratio wider in the horizontal direction than a reference aspect ratio using a transmission system for image signals having the reference aspect ratio, the wide aspect image signal being used as an image signal. In this method, the signals of the side panel part are rearranged above and below the signal of the center part of the image, and the signals of the side panel part are transmitted. A television characterized in that, when rearranging the signals in the center part above and below, the signals in the side panel part are frequency-divided and the signals expressing lower frequency components are rearranged and transmitted so that the signals expressing lower frequency components are arranged on the outer side. Signal transmission method.