JPH0431628B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a television system, in particular, the high-frequency components of a luminance signal are multiplexed to a television signal according to a standard system and transmitted, and on the receiving side, The present invention relates to a method for obtaining an image with improved resolution based on the above-mentioned high frequency components.

<Prior Art> In the current standard system, the bandwidth of the luminance information component in a television broadcast signal is suppressed to about 4.2 MHz.

<Problems to be solved by the invention> Most of the current television broadcasting equipment has the ability to process information well above 6MHz, and if this information is displayed on a video tube without being transmitted over radio waves, , it is possible to display fine images with well over 700 pixels per horizontal scanning line. Despite that,
When receiving a broadcast image transmitted over radio waves, the information is limited to about 4.2MHz due to current bandwidth, so the resolution of the received and displayed image is about 480 pixels per horizontal scan. has decreased to

The present invention aims to improve the horizontal resolution of received images while employing a standard method.

<Means for Solving the Problems> The television system according to the present invention includes a transmitting device and a receiving device.

The transmitter first divides the image screen into several blocks. Each block is composed of m pixels, and the pixels within the block are divided into n first pixels and m-n second pixels.

Within each block, only the first pixel is extracted,
After moving to the correction position at equal intervals, the brightness information is used as a brightness signal to create a television signal according to the standard method.

In order to transmit information regarding the second pixel, the difference between the average value of the luminance information of the first pixel and the luminance information of the second pixel is determined for each block, and the difference is multiplexed with the television signal and transmitted. .

The receiving device separates the luminance information of the first pixel and the difference signal from the received signal. The luminance information of the first pixel is returned from the above correction position to the original position before correction, and the brightness information of the first pixel is returned to the position where the second pixel existed.
Interpolation information corresponding to the average value of the luminance information of the first pixels on both sides is inserted to restore each block to the form of m pixels. Furthermore, the difference signal is added to the interpolation signal to restore the luminance signal. and,
The luminance information restored in this way is used as a luminance signal to display an image on the picture tube.

Each part of current television transmitting equipment has the ability to process more than 700 pixels per horizontal scanning line, so approximately two-thirds of the pixels are transmitted using standard television signals, and the remaining It is most effective to transmit information about one-third of the pixels by multiplexing narrowband signals. Therefore, as a guideline for forming blocks, (a) 3 pixels in the horizontal direction constitute one block, and the screen is divided horizontally.
It is divided into 240 blocks x 480 blocks vertically, and two pixels in each block are transmitted using the standard method.

(b) One block consists of 6 or 9 pixels, and 4 or 6 pixels in each block are transmitted in the standard method. The block may be arranged not only in a horizontal pixel arrangement but also in both horizontal and vertical directions.

(c) One block consists of 8 or 16 pixels, and 5 or 10 pixels of that block are transmitted using the standard method. This number is advantageous for processing using a binary system.

etc. are possible.

Furthermore, if the brightness information of the first pixel is used as is as the brightness information sent by the standard television signal, the brightness signal will be sampled at irregular intervals, and this will be sampled at irregular intervals. When received, it looks somewhat unnatural. This unnaturalness is caused by changing the luminance information of the first pixel to the second pixel corresponding to the amount of movement to the correction position as the luminance information to be transmitted.
This can be significantly improved by modifying the value to take into account the luminance information of the pixels.

<Operation> As described above, the luminance information of the second pixel is not transmitted as is, but is calculated by combining the average value of the luminance information of the adjacent first pixel and the luminance information of the second pixel. Since it is transmitted in the form of a difference signal,
The required bandwidth can be significantly compressed. Therefore, by using part of the scanning line, etc.
It can be multiplexed into a television signal relatively easily.

Furthermore, television images do not necessarily need to have high resolution over the entire area, and a considerable effect can be obtained if the important points are high resolution, so the above difference is applied only to a small number of blocks (about 100 to 500). You may also send a signal. The criteria for selecting blocks may include selecting blocks in descending order of luminance difference value, or selecting blocks with emphasis on the center of the screen, subtitles, etc. In this way, when only the difference signal of a specific block is sent, address information of the block may be added to the difference signal as necessary.

Moreover, when receiving with a currently used receiver, the resolution simply cannot be improved, and the image can be received as before without any problems, so compatibility can be achieved.

<Example> FIG. 1 shows a transmitting device, and FIG. 2 shows a receiving device.

In FIG. 1, a color video signal obtained by a color camera 1 is divided by a matrix circuit 2 into a luminance signal component and a color difference signal component. This luminance signal component is a high resolution signal with a bandwidth exceeding 6MHz.

The luminance signal component is 13.5M in AD converter 3.
The signals are sampled at a frequency of Hz, digitized, decomposed into pixel signals of 720 pixels per scanning line, and temporarily stored in the image memory 4. This accumulated data is sequentially read out in blocks of three pixels, and after being corrected in a pixel amplitude correction circuit 5 as will be described later, it is passed through a gate 6. The gate 6 is controlled by a thinning circuit 7, which blocks the central pixel signal in each block and allows only the pixel signals at both ends to pass.

Since the pixel signals passing through the gate 6 are at irregular intervals, they are once stored in the buffer memory 8, read out at equal intervals, converted to analog by the DA converter 9, and processed by the low-pass filter 10 to extract components exceeding 4.2MHz. is removed and supplied to the color encoder 11. On the other hand, the color difference signal component separated in the matrix circuit passes through the AD converter 12, the image memory 13, and the DA converter 14 in order, and undergoes time adjustment so that the timing matches the path of the luminance signal component described above. and color encoder 1.
Enter 1. The color encoder 11 synthesizes a color video signal compliant with the NTSC system based on these input signals, and sends this to the transmitter 16 via the mixer 15.

A part of the pixel signal that has passed through the thinning gate 6 is combined into an average value in an interpolation circuit 17, and combined with the pixel signal that has passed through a delay circuit 18 for timing adjustment. The combined signal is 3
The signal is made up of pixels, but compared to the three pixel signals before thinning at the gate 6, both ends are the same, but the center pixel signal is different. Reference numeral 19 denotes a subtraction circuit, into which the three pixel signals before thinning, whose timing has been adjusted in the delay circuit 20, and the three pixel signals generated by the above-mentioned combination are input in synchronization, and the difference between the two is input. is taken. This difference signal represents the difference between the average value of both pixel signals at both ends and the central pixel signal.

The selection circuit 21 selects only those difference signals having a certain magnitude or more, in order to reduce the burden on the subsequent transmission data creation section 22. The transmission data creation section 22 quantizes the received difference signal of each block into 4 bits and temporarily stores it in the memory 24 together with the address data created by the address counter 23. and 1
The accumulated data is inspected during the vertical retrace period after the end of the field, and 50 blocks that require high-frequency compensation are selected, and during the next field, the difference signal of the selected blocks is calculated as Read out continuously at low speed along with address data. Of course, on the other hand, the difference signal and address data for the new field are captured. The criteria for selecting the 50 blocks described above can be determined by the order of the magnitude of the difference signal or by placing emphasis on the center of the screen, using a computer circuit for this purpose.

The data read out at low speed by the transmission data creation section 22 is converted into serial data by the serial data section 25, and further compressed into address data by the compression section 26, and then sent from the carrier generator 28 by the modulator 27. modulate the incoming carrier,
The mixer 15 multiplexes the signal into a color broadcast signal.

In Figure 2, the received and detected signal is
The separator 30 separates the signal into high-frequency component data and a color broadcast signal mainly consisting of low-frequency components. The color broadcast signal is divided into a luminance signal component and a color difference signal component by the color decoder 31, and each is divided into a luminance signal component and a color difference signal component.
The data is digitized by AD converters 32 and 33 and then stored in image memories 34 and 35.
The luminance signal components stored in the image memory 34 are read out block by block as pixel signals at appropriate times, but the readout is performed at irregular intervals like the signal output from the thinning gate 6. The read pixel signal is subjected to processing similar to that of the interpolation circuit 17 and delay circuit 18 in FIG. 1 by a parallel circuit of an interpolation circuit 36 and a delay circuit 37, and then sent to an adder 39 .

On the other hand, the high-frequency component data separated by the separator 30 is sent to the memory 40 via the digital decoder 39, and a difference signal is written at the position specified by the address data included in the signal. Then, the difference signal read out at an appropriate time is sent to the adder 38, but at that time, the above-mentioned signal is added to the center pixel signal among the three pixel signals, which is the other signal input to the adder 38. Addition is performed so that the difference signals overlap. This addition output is subjected to processing in the elementary amplitude restoration circuit 41 that is opposite to that in the pixel amplitude modification circuit 5 in FIG. 1, converted into an analog signal in the DA converter 42, and then supplied to the matrix 43 as a luminance signal.

A dye signal is read out from the image memory 35 at a timing synchronized with the luminance signal, converted into an analog signal by a DA converter 44, and supplied to a matrix 43. The matrix 43 reproduces the color signals and displays them on the video tube 45.

Next, the operation of the above-mentioned apparatus will be explained with reference to FIG.

The luminance signal components separated by matrix 2 in FIG. 1 have a waveform as shown by curve 50. When this is sampled at 13.5MHz in AD converter 3 and digitized, a, b, c, d, e
It is decomposed into pixels such as..., and blocks A, B, etc. are constructed by putting together three of these pixels. Block A
The amplitudes of pixels a, b, and c at are Ha,
Hb, Hc.

At the thinning gate 6, the central pixel b is removed, leaving signals from pixels a and c only. Since this signal is irregularly spaced, it is processed in the buffer memory 8 and moved to correction positions a', c', d', and f'. Original pixel signals a, b, c, d, e...
has a bandwidth of just over 6MHz, so standard television cannot transmit all of it over the airwaves. 2, its bandwidth is compressed to just over 4MHz, which is sufficient to accommodate standard television radio waves.

The difference signal obtained by the subtraction circuit 19 represents the difference ΔH between the amplitude Hb of the center pixel b and the amplitude average value Hm of the end pixels a and b. The difference signal ΔH is generally smaller in magnitude than the pixel amplitudes Ha, Hb, Hc, etc., and the number of difference signals to be transmitted is limited to a small number by the transmission data creation unit 22, so that the difference signal ΔH is narrow. Since it can be transmitted over a wide band, it can be easily multiplexed into television radio waves.

On the receiving side, when receiving the above-mentioned television radio waves and reading them from the image memory 34, pixel a
and returns the pixel signal to the position c. Then, the interpolation circuit 37 inserts the average value signal Hm at the position of pixel b as an interpolation signal. On the other hand, the difference signal ΔH read out from the memory 40 in synchronization with the position of pixel b is added to the average value signal Hm in the adder 38, and the amplitude
Restored to Hb pixel signal. Therefore, pixel a,
Pixel signals having amplitudes Ha, Hb, and Hc for b and c are restored, and pixels based on these are displayed. In this image, information of 3 pixels per block is transmitted in the parts that require high resolution, so it is virtually impossible to obtain high resolution for the entire image, which is close to that of an image transmitted with a bandwidth of about 6 MHz. can.

When the above-mentioned television broadcast is received by a conventional receiver, it can be received without any problem based on the two-pixel signals with amplitudes Ha and Hc. However, in that case, the amplitudes sampled at pixel positions a and c are added to the pixel positions a' and c'.
Since Ha and Hc pixel signals are displayed, the image becomes somewhat unnatural.

The pixel amplitude correction circuit 5 in FIG. 1 and the pixel amplitude restoration circuit 41 in FIG. 2 are intended to eliminate this unnaturalness, and their operations will be explained with reference to FIG. 4.

In the pixel amplitude correction circuit 5 on the transmission side, the amplitudes of pixels a and c have a ratio of 1:3 between the moving distance from the original position to the corrected position and the distance from the position of pixel b to this corrected position, respectively. Therefore, it is corrected to Hab=3/4Ha+1/4Hb Hbc=1/4Hb+3/4Hc. While this information is transmitted as a luminance signal, the interpolation circuit 17
The average value Hm' of Hbc and Hbc is calculated and inserted in place of pixel b, and in the subtraction circuit 19, the difference signal Δ
H′ is created and the data is transmitted.

On the receiving side, the interpolation circuit receives the pixel signal.
The H'm component was reproduced based on Hab and Hbc and read out from the memory 40. The ΔH' components are added in an adder 38 to reproduce the pixel signal Hb of pixel b. Furthermore, the pixel amplitude restoration circuit 41 reproduces pixel signals Ha and Hc from the three pixel signals Hab, Hb, and Hbc. As a result, the pixel signals Ha,
A detailed image based on Hb and Hc is displayed.

Furthermore, when the above broadcast radio waves are received by a conventional receiver, pixels with amplitudes Hab and Hbc are displayed at pixel positions a' and c', respectively, but this is different from the true amplitude Ha. ′ and Hc′, the above-mentioned unnaturalness is largely eliminated.

<Effects of the Invention> As described above, according to the present invention, even though the standard method is adopted and the bandwidth of the luminance signal is limited to about 4 MHz, the receiving side can effectively
It is possible to display high-resolution images close to those sent using a 6MHz bandwidth. Moreover,
Since the format of the radio waves does not deviate from the standard format, when received by a conventional receiving device, it is possible to display an image with a conventional resolution without any problem.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a transmitting device in an embodiment of the present invention, FIG. 2 is a block diagram of a receiving device in the same embodiment, and FIG. 3 is a waveform when brightness correction of the first pixel is not performed in this invention. 4 are waveform diagrams when the brightness of the first pixel is corrected in the present invention. 4... Image memory (block division means),
5... Pixel amplitude correction circuit (first pixel luminance information correction means), 6... Thinning gate (n first pixel extraction means), 8-16... Standard format television signal creation means, 17... Interpolation circuit (luminance signal average value generation portion of the first pixel), 19... Subtractor (means for obtaining difference information), 22... Transmission data generation section (block selection means), 23... Address counter (address data generation part), 15... Mixer (multiplexing part), 30... Separator, 34... Image memory (means for placing luminance information at the first pixel position),
36... Interpolation answer (interpolation information insertion means), 38...
...Adder, 45...Picture tube.

Claims (1)

[Scope of Claims] 1. Means for dividing an image signal into blocks each consisting of m pixel signals;
means for extracting n (n<m) first pixel signals by removing pixel signals; and obtaining a difference signal between the second pixel signal and the average value of the adjacent first pixel signals. means for moving the first pixel signals to the correction position at equal intervals; means for multiplexing the difference signal on the first pixel signal placed at the correction position; and receiving the same; means for separating the first pixel signal and the difference signal, means for returning the separated first pixel signal from the correction position to the original position before correction, and a second pixel signal between the first pixel signal. means for inserting an interpolation signal corresponding to the average value of the first pixel signal adjacent thereto at the position where the pixel signal was present;
and means for adding the difference signal to the interpolation signal to restore a second pixel signal. 2 means for dividing the image signal into blocks each consisting of m pixel signals;
means for removing n first pixel signals (n<m); and means for moving the extracted first pixel signals to a correction position so that their mutual spacing becomes equal; The correction is made by combining the first pixel signal and the second pixel signal at a rate inversely proportional to the distance from the original position of the first pixel signal and the position where the second pixel signal existed to the correction position. means for obtaining a corrected pixel signal at a position; means for obtaining a difference signal between the second pixel signal and the average value of the corrected pixel signals existing on both sides of the position where the second pixel signal was present; means for multiplexing the difference signal on a signal and transmitting the same; means for receiving the difference signal and separating the modified pixel signal from the difference signal; means for inserting an interpolation signal corresponding to the average value of the corrected pixel signals;
and means for restoring a first pixel signal at a position before correction and having a magnitude before correction from the restored second pixel signal and the corrected pixel signal. High resolution television system.