JPS5877373A - Television signal processing circuit - Google Patents

Abstract

PURPOSE:To obtain a reproduced picture with very high precision, less deteriorate the reproduced picture even with the movement of picture, by detecting moving information of the picture of a television signal, and selecting an optimum interpolation means out of a plurality of the means through its detected signal. CONSTITUTION:A television signal from an input terminal 12 is delayed at field memories 14, 15 for 262H and 263H respectively, and a signal representing the movement of picture elements is outputted from a subtraction circuit 19. An output of the field memory 14 is delayed by 1H at a line memory 16, and an average value of the picture elements of 2-line is outputted at an addition circuit 17 and a coefficient circuit 18. The picture elements to be interpolated is obtaind at multiplication circuits 21, 22 and an addition circuit 23 in response to the moving coefficient from a coefficient circuit 20. An output time-axis-converted at time axis conversion circuits 24, 25 is switched at 1/2H period at the switching circuit 20, allowing to obtain a very high precision television signal doubling the desired scanning line number at an output terminal 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television signal processing circuit, and more specifically, to a television signal processing circuit that receives a television signal that is currently being processed, and obtains a television signal with twice the number of scanning lines through interpolation. Related to signal processing circuits.

Currently, television receivers with larger screen sizes are being developed. When the screen size is enlarged, the scanning line spacing of the displayed television image naturally widens, and the original resolution is insufficient, making it impossible to obtain high quality images. In addition, there is an increasing demand for high-quality images that are even finer than the image quality of conventional television receivers.

In response to these demands, high-definition televisions with double the number of scanning lines are being developed. In this case, a high-resolution, high-quality television image can be obtained, but changing the number of scanning lines from the camera requires changing the existing transmitter and receiver, so it is difficult to put it into practical use. There are technical issues to be solved.

There are many economic challenges – and it will take a long time.

On the other hand, a high-resolution television receiver that receives the current Chilevision broadcasting signal and performs t-interpolation between the scanning lines to substantially double the number of scanning lines is being considered.

That is, the received signal is subjected to time compression processing in order to multiply the number of transmitted scanning lines by t-2, and the scanning lines spanning two fields are made into a single frame signal. The NT8C television signal currently broadcast in Japan is 1/60
A field signal with 2,625 scanning lines is interlaced and transmitted every second, and two fields constitute a frame signal with 525 scanning lines. Therefore, when image signals from two fields separated by 1/60 seconds are combined to form a single frame, the number of high-definition scanning lines is doubled if the image is stationary or has little movement. If an image is obtained, but the image changes over time, x/60
Since it is a composite of two images that moved for seconds, there is a problem that the image quality deteriorates.

Therefore, an object of the present invention is to provide a television receiver which receives an interlace-scanned television signal and artificially doubles the scanning line by t-2 inside the receiver, so that the reproduced image can be changed even by the movement of the image. Detailed reproduced image with little deteriorationg
The object of the present invention is to realize a television signal processing circuit that obtains II.

In order to achieve the above object, the present invention detects motion information of an image of the television signal when creating an interpolated scanning signal from a received television signal, and uses the detected signal to select the optimal one from among a plurality of types of interpolation means. It is characterized by being configured so that it can be selected.

That is, a detection circuit that obtains image motion information from interframe difference signals of interlaced television signals, a first interpolation circuit that uses scanning lines within a field, and at least a previous field (or previous and subsequent fields). a second interpolation circuit that utilizes the scanning Il of the image; and a mixing ratio of the output of the first interpolation means and the output of the second interpolation means is controlled by the output of a detection circuit that obtains motion information of the image. The mixing circuit and the time axis of the above mixed output are halved.
This television signal processing circuit has a time axis conversion circuit that compresses the input television signal to obtain a television signal with twice the number of scanning lines of the input television signal.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows the general configuration of a television receiver in which the scanning lines of an input television signal are artificially doubled by interpolation.

Regarding the current NTSC system television broadcast signal as a signal source, the television signal with 525 scanning lines, horizontal frequency 1 & 75kHz x vertical frequency 60Hg% 2:1 interlace is the normal NT8C system television reception. A demodulator l similar to the machine is used to obtain a Y signal, a □■ signal, a Q signal, a horizontal synchronizing signal H0, and a vertical synchronizing signal V.
, I, and Q signals are input to the time axis conversion circuit 2 as explained in FIG. 2, and the main scanning period is compressed.
, Q', and are applied to the image amplifier circuit and chroma circuit 4. Further, the H and V signals are converted into H' and V' K by the synchronization signal converter 3, the scanning lines are doubled, and the display device 5 receives the signals as drive signals for the next television signal.
added to.

FIG. 2(A) shows the conventionally known time axis conversion circuit 2.
FIGS. 2A and 2B are diagrams illustrating the states of scanning lines of an input television signal and an interpolated television signal, respectively. The time axis conversion circuit 2 shown in FIG. 1 includes circuits as shown in FIG. 2(A) for each of the Y, I, and Q signals.

The Y signal will be explained below to simplify the explanation.

A Y signal corresponding to the current television signal interlaced every 1000 seconds is applied to the input terminal 6 as shown in FIG. A portion of the signal is delayed by the chef yield period (1/60 second) by the field memory 7 and is input to the time axis conversion circuit 8.9 together with the input signal. The ljI axis conversion circuit 8.9 converts the signal into a signal compressed to the time axis t1/2H. These output signals are 1/1 by the switching circuit 10.
By switching every 2H, a horizontal scanning period is 1/2H and a time axis conversion signal is obtained at the output terminal 11.

Therefore, as for the reproduced image, a television image in which the horizontal scanning lines are doubled (525 lines) is obtained every 1/60 seconds, as shown in FIG. Furthermore, if the horizontal and vertical drive signals are created so that the second and third fields are interleaved, the number of horizontal scanning lines in one frame (two fields) becomes one.
050 images are obtained.

However, among the 525 scanning lines in each field in figure (C), half of the 2625 scanning lines are in the previous field, i.e., l/
This is a pseudo signal created by interpolating the IljgI signal from 60 seconds ago, so if the image (subject) is moving or has many temporal changes, it is a composite of the previous field image and the current field image. ll1if# for 1760 seconds
When changes (image movement, brightness, color changes, etc.) occur rarely, image quality deteriorates.

In order to explain the principle of the television signal processing circuit according to the present invention, FIG. 3 is a perspective view showing three consecutive fields of scanning lines li of a current television signal. In the figure, the broken line for the first field, the broken line for the second field,
The dotted line in the field and the solid line in the third field are the signals transmitted to the current east, and from these signals, for example, a pseudo scanning spring signal m is generated by interpolation between the scanning lines t and n of the jI2 field.
When creating 2, depending on my movement information, the second field's scanning line to"t - the first one located at the same position as D and m used - uses the signal of the third field's scanning line. To be more specific, when creating pixel Y on the scan 41m created by interpolation, if the subject moves
When this is the case, interpolation is performed from the upper and lower scans 1st*n of the same field, which are most similar in terms of time. In addition, if the subject is close to a still image with little movement, the closest one in the spatial image area,
That is, pixels X and z in the same position as the above-mentioned pixels in the first and third fields are used.

Note that if the subject is moving, the resolution will in principle deteriorate because pixels from different areas are used, but human vision has a characteristic that the resolution decreases for moving objects. Therefore, the reduction in resolution due to the interpolation described above is not a practical problem.

FIG. 4 is a diagram illustrating a main part of an embodiment of nine apparatuses implementing the television signal processing method according to the present invention, that is, time 1lI
FIG. 2 is a block diagram showing the configuration of an Il conversion circuit. The television signal (eg, luminance signal Y) inputted from the input screen 12 is delayed by 262H%263H (H is the horizontal scanning period) in the field memories 14 and 15, respectively. When the input signal is pixel 2 of the third field in Figure 3 (the signal level is represented by 2), the output of the field memory 15 is once the X of the first field one frame before.
(The signal level is represented by X). Above signals X and 2
is applied to the subtraction circuit 19 and converted into a difference signal of % (Z-X), that is, a signal representing the dynamic tI tube of pixel Y in the second field.

On the other hand, the output of the field memory 14 is the signal of the scanning line n of the second field, and the output is IH in the write/memory 16.
, to obtain the scanning iIt signal. This scanning line n
When the pixel values of and t are obtained from the addition circuit 17% coefficient circuit 18, the average value is obtained.

Let this be the interpolated value a from the signal within the same field.

Using this interpolated value a, the interpolated value b1 from the previous field, and the motion coefficient obtained by the motion coefficient circuit 20, the value Y of the pixel to be interpolated is set to y=@b+(1-k)・1 ... Song... (υ
Find it as. Multiplication circuit 21.22% addition circuit 23 is a circuit for calculating the above equation. - a new i-scan I! consisting of the signal of the scan line n of the second field and the interpolated signal Y obtained above; m signals are input to the time axis conversion circuits 24 and 25, and the output thereof is input to the switching circuit 20.
By switching at a cycle of 172H, a high-definition television signal with the desired number of scanning lines t2 is obtained at the output terminal 13.

In the above embodiment, the interpolated value of the stationary 11i (# is the signal X of the previous field, but from the addition circuit and the 172 coefficient circuit, it is also possible to use the average value of X and 2. In this way, Fine difference sound components cancel each other out, making it possible to obtain a higher quality image 1#!.In addition, the output k of the motion coefficient circuit 20 is converted into binary signals 0 and 1' (which represent the presence or absence of motion).
k=0...There is movement.

If k=1 (no movement), the multiplier circuits 21, 22 and the adder circuit 23 can be placed in the switching circuit to simplify the 11Lc circuit.

FIG. jI5 is a diagram showing another practical configuration of the television signal processing circuit according to the present invention, particularly the interpolation scanning signal generation section which is the main part thereof.

In the embodiment shown in FIG. 4, the scanning method after doubling the scanning lines is one in which a frame signal is generated every 1760 seconds with 7525 scans (m-1) of l frames, and no interlacing is performed. The embodiment shown in FIG. 5 further performs interlacing. Components in this figure are given substantially the same numbers as those in FIG. 4, and detailed explanation thereof will be omitted.

In this embodiment, the average value signal obtained from the output signal (interpolated signal) of the field memory 14 and the signals before and after the fil field by the adder circuit 17 and the coefficient circuit 18 is the former IIi The latter is directly illuminated into the coefficient circuit group 30 via a line memory 26, 27, 28 which obtains a delay of IH, 2H. The coefficient circuit group multiplies the values in the circles for reasons described later. The output of the coefficient circuit described above is illuminated directly or via the adder circuit group 31 and further through the changeover switches 32, 33, 34, 35t- to the adder circuit 36, 37 or the expansion/subtraction circuit 38, 39.

The output of the subtraction circuit is applied to the addition circuits 36 and 37 via coefficient control circuits 40 and 41.

The outputs of the adder circuits 3 and 37 are respectively sent to the time axis conversion circuit 24.
．． 26, the time axis is compressed to 1/2.

The changeover switch 26 switches the output of the time axis conversion circuits 24 and 25 every cycle, and then passes through the coefficient circuit 42 for adjusting the coefficients multiplied by the coefficient circuit group 30 to double the number of scanning lines. This results in a signal that is interlaced. Note that when the time axis conversion section is constructed of a digital circuit, a D/MU conversion circuit is added to the output side of the coefficient circuit 42. The above-described practical operating principle will be explained with reference to FIGS. 6, 7, and 8. FIG. 6 shows, on the same drawing, the positional relationship between the scanning lines of a current television signal and a television signal whose number of scanning lines has been converted and interlaced according to the embodiment shown in FIG. The solid line and the dotted line indicate the position of the scanning line, and the current television signal is composed of the first field (marked with a solid IIO) and the second field (marked with a broken line Δ), and the signal of the scanning line in the above embodiment is The field scans the positions of the solid line and dashed line Il (indicated by a * mark), which are the scanning lines of the above-mentioned current television signal, and the second field scans the position of the point II (indicated by a * mark) which is interlaced between the scanning lines of the first field. (shown).

In this embodiment, as can be seen from FIG. 5, the interpolation operation changes depending on the motion information (circuit 19.2G).

41, 40, etc.) as well as the coefficient circuit group 30 and the adder circuit group 31.
Attempts have been made to improve the frequency characteristics of signals for the reasons described below.

For the fl[L direction of the screen, the image can be considered to be sampled by scanning lines. If the number of scanning lines is taken as a sampling frequency unit in the vertical direction, the current television signal has a sampling frequency of 525 lines, of which 2625 lines are used for field images.

That is, from the discussion of the previous embodiment, it can be considered that the sampling frequency of the current television signal in the stationary range is 525, and that of the moving image is 2625.

Furthermore, the sampling frequency after scanning is multiplied by 112 (with interlacing) is 1050 lines. Scan II doubling process is! 1 @
Interpolate between sample points in the direction! & Equivalent to the problem of designing a logic circuit. Figure 7 shows the sampling frequency f in the vertical direction of the image.
Ma is expressed on the horizontal axis using the number of scanning lines as a unit.
25 and 525 are the field image (moving image) and the sampling frequency of one frame (still one), respectively, 105
0 indicates the sampling frequency after conversion. Therefore, the interpolation circuit constitutes a Hitotsubashi interpolation filter, and among the bands from θ to 525, the band of (sampling frequency before conversion)/2 is used as a pass band, and the frequency of one sampling frequency and its integral multiples is all centered. A low-pass filter (low-pass filter) that suppresses harmonic components generated as
LPP).

In other words, in the case of moving images, the sampling frequency is the scanning line frequency (262,5 lines) within the field, so
An LPF that passes vertical frequency components of 72 or less,
Similarly, in the stationary 1 mode, the scanning line frequency within the frame (525
This is an LPF that allows less than 1/2 of the total amount of light to pass through. Songs aH, (f), and H in Figure 7.

<i) shows the frequency characteristics of the interpolation filter example,
H,(f) is the LPF for a moving image, and H,(f) is an LPF for a still image. Its transfer characteristic is expressed by the following equation.

・・・・・・・・・・・・・・・(3) The impulse response of a filter with the frequency characteristics of equation (2) is the sampling period (
In other words, the value for each scanning line interval (after conversion) is (1, 2,
3,4,3,2,1)/16. This is an interpolation filter that interpolates sample values with ties. In this dynamic processing mode, only signals from the same field can be used.Next, as shown in the moving image mode in Figure 8, the sample value of the input signal is calculated every four sampling periods of the impulse response. , the signal of the scanning line marked φ is interpolated from the scanning line indicated by the solid line (marked O), and in the second field, the signal of the scanning line marked φ is interpolated from the scanning line indicated by the broken line (marked Δ) af: the coefficient (6, 2) shown in the figure. Interpolation will be performed.

In still image mode, all scan lines of the input signal are available for interpolation. The impulse response of equation (3) is (-1°-1,
5, 10, 5, -1, -1)/16, so in the first field, the scan mt is indicated by the * line.

In the second field, the signals shown in FIG. A signal with specific frequency characteristics can be obtained.

That is, in FIG. 5, the vertical position in FIG. 8 is determined by field memories 14 and 15 and lie/memories 27, 28, and 29, and one switch 32, 33, 34
and 35 alternately (
The motion detection circuit 19 and the coefficient control circuit 20 change the coefficients of the coefficient circuit 40. Let's do it.

In the above description, a television system with 525 scanning lines is described. However, television signals of other scanning systems (for example, PAL system, etc.) can be processed in the same way. In the ninth embodiment, a monochromatic television signal has been described, but it is clear that a color television signal can be similarly converted by providing a similar circuit for each of the three primary color signals or the nine luminance color difference signals.

Further, the coefficients of the interpolation filter described in the embodiments are merely an example, and it is obvious that other coefficients can be used in the same manner.

According to the present invention, in a portion of a television signal where one object is stationary, a high-definition signal with twice the number of scanning lines is generated by using the information of all the scanning lines of two fields spanning the frame. can get. Furthermore, in the moving image part, the scanning lines in the field are used to double the number of scanning lines, so images with less deterioration due to movement can be obtained.
Converts and displays current TV signals to high-definition, high-quality 11i (&), making it possible to realize an economical high-definition TV transmission system.

Furthermore, in the future, if all TV cameras become high-definition TVs with twice the number of scanning lines, current TV programs will also be converted to 16-definition TV signals using the unreleased method.
The number of programs that can be displayed on high-definition televisions will increase, and we can expect a wide-spread effect on the spread of high-definition televisions. Moreover, if a television signal made high-definition by the processing method of the present invention is used for electronic printing, any television picture gII can be printed as a high-definition picture with little deterioration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the general structure of a television receiver in which scanning 11t of the input η television picture signal is doubled;
FIG. 2 is a block diagram for explaining the principle of the time axis conversion circuit 2 in FIG. FIGS. 4 and 5 are circuit diagrams of an embodiment of means for obtaining an interpolated signal, which constitutes a main part of a television signal processing circuit according to the present invention, and FIGS. 6, 7, and 8 are diagrams for explaining the operation of the embodiment of FIG. 5, and are interpolated with the input television signal, respectively. Figures 6, 7, and 8 are diagrams showing the positional relationship of the scanning lines of the television signal, and interpolation. 6 is a diagram showing a frequency characteristic diagram of a filter formed by the circuit and a relationship between scanning lines and coefficients of a coefficient circuit group in the embodiment of FIG. 5. FIG. DESCRIPTION OF SYMBOLS 1... Demodulation device, 2, 24. 25... Time axis conversion circuit-3... Synchronization signal conversion device, 4... Eirin amplification and chroma circuit, 5... Display device, 6.12.
...Input terminal, 7...Field memory, 8.9...
・Time axis conversion circuit% 10, 26...Switching circuit, 11
．． 13... Output terminal, 14, 15, 16, 27.28
．． 29...Delay memory, 17, 23, 36.37...
-Addition circuit, 18.42...Coefficient circuit, 19,38.
39... Subtraction circuit, 20-... Coefficient circuit, 21, 22
．． 40.41... Multiplication circuit. ′! h 1 Figure ■ 3 Figure 'VJ4 Figure 1

Claims (1)

[Claims] 1. A television signal processing circuit that receives a television signal and doubles the number of scanning lines of the input television using the input television signal and an interpolation signal obtained from the input television signal. In the above, the means for obtaining the interpolation signal includes a detection circuit that detects the motion of the subject from the interframe difference signal, a first interpolation circuit that uses scanning lines in the field, and at least one of the previous field or the subsequent field. A second interpolation circuit utilizing the above-mentioned test mt-, and a mixing circuit that varies the mixing ratio of the outputs of the first and second interpolation circuits based on the output of the detection circuit. Television signal processing circuit ゛2. In the first item, the -output circuit determines whether or not there is movement of the subject, and the mixing circuit changes the output of the first interpolation circuit to 1 if there is movement of the subject. ．． 1. A television signal processing circuit characterized in that it is configured to output an output of the second interpolation circuit in the case of presence or absence. 3. In the description in paragraph 1, the second interpolation circuit is 262
It consists of first and second delay memories connected in cascade with a horizontal scanning period (H) of 263H, and the detection circuit uses the output of the second delay memory as the output of the second auxiliary circuit. The first interpolation circuit adds the output of the first delay memory and the output delayed by t-IH of the first delay memory. The mixing circuit multiplies the output of the first interpolation circuit by (1-k)7 times (
0<k<1)L% A television signal processing circuit comprising a circuit that doubles and adds the output of the second interpolation circuit. 4. In the description in item 1, the interpolation circuit of the group 1 is used to calculate the impulse response of the filter that passes the vertical I[frequency components of (scanning line frequency) of 72 or less] to the plurality of scanning line signals in the field. Corresponding to this, the second interpolation circuit includes a filter that passes signals having a vertical frequency component of (scanning line frequency) or less in the frame to the scanning line signal in the field and at least one of the plurality of scanning line signals before and after the field. 1. A television signal processing circuit comprising: a circuit for adding signals obtained by multiplying Impa and Rus L answers by coefficients corresponding to each other.