JPH0832025B2 - Motion-aware signal processing circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal processing circuit of a television signal, and more specifically, a television signal (interlaced scanning signal) which adopts an interlaced scanning method as a scanning method. ) To an interpolation signal created from the interlaced scan signal to create a progressive scan signal.

[Background of the Invention]

In digital televisions and the like, which have been developed in recent years, a system for converting interlaced scanning signals into progressive scanning signals and displaying the same on the receiving side tends to be adopted because it can prevent screen flicker.

Under such circumstances, a signal processing circuit for converting a television signal from an interlaced scanning signal to a progressive scanning signal is required. In such a signal processing circuit, a scanning line between 262.5 scanning lines for one field is provided. For the convenience of interpolating to produce a progressive scanning signal having 525 scanning lines, an interpolating circuit for producing an interpolating signal is used.

As is well known, the interpolating circuit is an inter-field interpolating circuit (an interpolating signal in the field is Circuit created using the scanning signal in the field) and 2 if the image is a moving image
There is an intra-field interpolation circuit (a circuit that creates an interpolation signal in the field using a scanning signal in the field) that is used because no disturbance such as a double image occurs.

In other words, the inter-field interpolator is suitable for still images, and the intra-field interpolator is suitable for moving images.If you mistakenly use the inter-field interpolator for still images, flicker will occur and resolution will deteriorate. On the other hand, when the inter-field interpolation circuit is used for a moving image, a double image is generated and the image deteriorates.

Therefore, conventionally, it is checked whether or not the image is moving (whether or not it is a moving image) from an inter-frame difference signal obtained by comparing two scanning signals taken out at intervals of one frame, and if it is a moving image. A technical idea has been proposed in which an intra-field interpolation circuit is used and an inter-field interpolation circuit is used for a still image.

For example, in Japanese Patent Laid-Open No. 58-205377, the amount of motion of an image is detected based on the inter-frame difference signal, and the characteristic of an interpolation filter as an interpolation circuit is changed according to this amount of motion.

This method is based on the amount of motion of the detected image, and if the amount of motion is small, the signal obtained by inter-field interpolation is mainly used, and if the amount of motion is large, it is mainly obtained by inter-field interpolation. By using such a signal, it is possible to use a progressive scanning signal with little deterioration for both still images and moving images.

However, since the motion amount of the image is obtained based on the inter-frame difference signal, accurate motion detection cannot be performed for fast motion. Interpolation may be performed, which may cause deterioration such as a double image or a rough scanning line structure.

For example, as shown in FIG. 2, when the image J of the object moves from the top to the bottom of the screen P, interlaced scanning is performed with the vertical axis in the vertical direction of the screen and the horizontal axis in the time axis. FIG. 3 shows the movement of the object image using the scanning lines.

In FIG. 3, a circle indicates a scanning line 1 (cross section). When the interpolation scanning line indicated by the triangle mark of the M-th field is created, since it is a moving image, it is necessary to perform the intra-field interpolation, but as is clear from FIG. Scan line l in M-1) field
_When the difference between _M-1 and the scanning line l _{M + 1} in the second (M + 1) field is taken, the difference is zero because the information of both scanning lines is the same, and accordingly, from the inter-frame difference signal, the position of the triangle mark No movement can be detected. Therefore, inter-field interpolation, which is still image processing, is performed on the moving image, and the above-mentioned deterioration occurs.

Further, for a fine pattern, even a relatively slow movement may similarly cause a false detection of the movement.

In the known example, the detected motion amount is subjected to LPF (low-pass filter) processing to prevent the motion amount from being erroneously detected.

For example, when the object image J moves as shown in FIG. 4 (a), the amount of motion detected by using the inter-frame difference signal is as shown in FIG. 4 (b). Since there is a range of zero and erroneous detection occurs, processing for correction is performed, and the corrected movement amount shown in FIG. 4 (c) is obtained.

However, in this method, a similar pattern movement amount is generated depending on the design, and the moving image processing is performed on the still image, so that there is a possibility that the resolution is lowered or flicker occurs.

For example, when the two frames W ₁ and W ₂ slowly move as shown in FIG. 5 (a), the detected motion amount is the same as that in FIG. 4 (b), and therefore the corrected motion amount is also the Since it is the same as in FIG. 4C, moving image processing is performed on the signal S between the frames even though it is a still image.

In addition, how fast the movement can be prevented from being detected incorrectly is preset by the constant of the circuit. Therefore, it has no effect on motions exceeding this speed.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned problems of the prior art, and to perform accurate scan line interpolation by performing error-free motion amount determination even for fast-moving images or images with fine patterns. It is an object of the present invention to provide a motion adaptive signal processing circuit capable of doing the above.

[Outline of Invention]

To achieve the above object, the present invention provides a first interpolating means for creating an inter-field interpolated scan line signal for a still image from an interlaced scan television signal, and a moving image field for the interlaced scan television signal. A second interpolating means for creating inter-interpolation scanning line signals, and scanning line signal synthesizing means for synthesizing the inter-field interpolation scanning line signals and the intra-field interpolation scanning line signals, the interlaced scanning television In a motion adaptive signal processing circuit for creating a sequential scanning signal from an interpolation scanning line signal synthesized by a scanning signal and the scanning line signal synthesizing means, based on the inter-frame difference signal of the interlaced scanning television signal, Motion information detecting means for detecting the presence / absence of motion of an image represented by the television signal and outputting it as motion information; Uptake branched motion detection output from the output combining means, after delaying (one field -0.5H) period and (1 field + 0.5H) period respectively, to synthesize the two,
An attenuator that multiplies this composite output by a predetermined attenuation coefficient and outputs the result, and the motion information from the motion information detector and the output from the attenuation delay unit are taken in, combined, and output as the motion detection output. The motion output synthesizing means is provided, and the synthesizing in the scanning line signal synthesizing means is controlled by the motion detection output from the motion output synthesizing means.

As a result, the motion adaptive signal processing circuit according to the present invention can hold the once detected motion information for the next several field periods. This means that it is possible to refer to the motion information detected over several fields before the current field when determining the current field.

Example of Invention

FIG. 1 is a block diagram showing a motion adaptive signal processing circuit which is a prerequisite for understanding one embodiment of the present invention.

In FIG. 1, 1 and 2 are the first and second field memories (one field is 262.5H to be precise, but here, for convenience, they are represented by 262H and 263H), and 3 is the first.
Line memories, 4,5 are first and second addition circuits (averaging circuits for taking average values), 6 is a mixing circuit, 7 is a subtraction circuit, 8 is an absolute value unit, and 9 is an interframe difference signal. A motion amount converter, 10 is a third field memory, 11 is a second line memory (note that since the field memory 10 is configured as 262H, by adding 1H of the line memory 11 to this, It is intended to obtain a delayed output of 263H),
Reference numeral 12 is a maximum value unit, 13 and 14 are first and second time axis compression circuits, 15 is a switch, and 16 is a motion detection circuit.

Of the first and second field memories 1 and 2 connected in series, the same position on the screen is scanned for one frame period from the input end of the first memory 1 and the output end of the second memory 2. Two signals are obtained. The inter-frame difference signal of these two signals is obtained by the subtraction circuit 7, and the absolute value of the inter-frame difference signal extracted via the absolute value unit 8 is input to the inter-frame difference signal / motion amount converter 9 to detect the motion amount. To do.

Here, the absolute value of the inter-frame difference signal input to the inter-frame difference signal / motion amount converter 9 is also 8 bits if the input television signal is quantized with 8 bits. On the other hand, if the output motion amount is, for example, 3 bits, the mixing ratio of the mixing circuit 6 described later can be controlled in eight steps, and the still image and the moving image can be switched smoothly.

Two signals obtained by delaying the motion amount output from the inter-frame difference signal / motion amount converter 9 by the third field memory 10 and the second line memory 11 for approximately one field period, and the two signals not delayed. By inputting the three motion amounts together with the maximum value unit 12, the motion amount at the position of the interpolated scanning line and the motion amount at the positions of the scanning lines above and below (see FIG. 6 described above) can be calculated. Find the maximum value.

The memory capacity of the third field memory 10 and the second line memory 11 is 3 as described above.
Since it may be expressed in bits, the first or second field memory 1, 2 for delaying the television signal
And the capacity of each of the first line memories 3 may be half or less.

The mixing circuit 6 includes a moving image intra-field interpolation signal output from the first adding circuit (averaging circuit) 4 and a still image output from the second adding circuit (averaging circuit) 5. The mixing ratio with the inter-field interpolation signal is controlled and output by the output of the maximum value unit 12.

The interpolated scan line signal thus obtained and the scan line signal of the current field are respectively supplied to the first and second time axis compression circuits 13 and 14.
, And the time axis is compressed to 1/2, the switch 15 is switched for each scanning period of the sequential scanning to alternately output the two scanning line signals, thereby obtaining the sequential scanning signal at the output. To do so.

According to this circuit, when detecting the motion of the image, the motions of all the pixels used to create the interpolated scan line are obtained, and accurate motion detection can be performed. Even in this case, when the motion amount to be detected in the past by one field period is obtained, the detected motion amount itself is delayed by one field period instead of delaying the image signal by one field period. Therefore, as described above, it is sufficient that the amount of motion is about 3 bits, and the required memory capacity can be reduced.

FIG. 7 is a block diagram showing the main part of one embodiment of the present invention.

The figure is, in essence, a motion detection circuit in the broken line portion in FIG.
16 shows specific circuit examples in the case of the present invention.
In FIG. 7, 17 and 19 are respectively the first and second maximum value units, 18 is a multiplier of coefficient α (α <1), and others are the same as those in FIG.

In the present embodiment, the motion amount output for controlling the mixing circuit 6 is delayed by approximately one field period (to be exact,
Output delayed by 262H by field memory 10 and 1H via line memory 11, that is 263H in total
Of the output delayed for a period, the maximum value is output by the maximum value unit 17) and then multiplied by α by the multiplier 18 (α <1),
The maximum value 19 obtains the larger one of the output of the motion detection circuit in the past of one field period multiplied by α and the output of the motion amount currently detected, and sets it again as the output of the motion detection circuit.

According to the present embodiment, once the motion is detected, even if the motion amount output detected from the next field becomes zero, it is multiplied by α (α <1) for each field for several field periods,
The amount of movement can be connected. Accordingly, for example, when a still image and a moving image are frequently switched due to the influence of noise or the like, resulting in an unnatural image, this can be reduced.

When the motion adaptive scanning line interpolation processing according to the present invention is performed on a color television signal, the following is performed.

First, in the case of a color television signal of the TCI signal type in which a luminance signal and two color difference signals are time-axis compressed and then time-axis multiplexed, as in the case of a monochrome television signal, as shown in FIG. Also, it can be converted into a signal for progressive scanning by the embodiment described with reference to FIG. After this, the time axis is expanded and then converted into RGB3 primary colors for display.

As described above, since the TCI signal can be processed by the same circuit for the luminance signal and the color difference signal, the circuit scale can be reduced.

Next, in the case of a color television signal in which the luminance signal Y and the color difference signal C are frequency-multiplexed as in the NTSC system, Y / C
After the separation, the signal processing according to the present invention is performed on each of Y and C.

An embodiment in this case is shown in FIG. In FIG.
Reference numerals 20, 21 and 22 are scanning line interpolation circuits (signal processing circuits) having the same circuit configuration as that of the embodiment of the present invention described with reference to FIGS. 1 and 7.

In the present embodiment, the luminance signal and the two color difference signals after the separation are independently subjected to the same processing as that described with reference to FIGS. No explanation of circuit operation would be necessary.

Note that the color difference signal has a narrower required frequency band than the luminance signal, and therefore the sampling frequency is generally about 1/4 of the sampling frequency of the luminance signal.

Therefore, in the present embodiment, the scanning line interpolation circuits 21 and 22 for color difference signals can have a lower operating frequency than the scanning line interpolation circuit 20 for luminance signals, and the circuits can be easily realized. Further, the required memory capacity may be about 1/4 of the luminance signal for each of the two color difference signals, and the memory capacity can be reduced.

Further, if the signal processing according to the present invention is performed after converting the separated Y / C into the RGB three primary colors, it is only necessary to use circuits having the same configuration. An embodiment in this case is shown in FIG. In FIG. 9, reference numerals 23, 24 and 25 are scanning line interpolation circuits (signal processing circuits) having the same configuration as that of the embodiment of the present invention described with reference to FIGS. 1 and 7.

In this embodiment, the scanning line interpolation circuits 23, 24, and 25 use exactly the same circuits, so that the system configuration can be simplified as a whole.

〔The invention's effect〕

According to the present invention, in the adaptive signal processing circuit, about 1
With a small memory capacity called the field capacity, motion information detected over multiple fields before the field can be referred to the field, so even when a fast-moving image or an image with a fine pattern moves, Motion detection Accurate motion detection without omission. Therefore, scanning line interpolation can be appropriately performed for each of a still image and a moving image, and a high-quality motion responsive interlace / sequential scan conversion processing circuit without image deterioration can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit which is a premise of one embodiment of the present invention, FIG. 2 is an explanatory diagram showing a falling object image, and FIG. 3 is an explanatory diagram showing a state in which a motion of an image is erroneously detected. FIG. 4 is an explanatory view showing a conventional method for preventing erroneous motion detection, and FIG. 5 is an explanatory view showing problems of the conventional method.
FIG. 6 is an explanatory view showing the concept of motion detection according to the present invention, FIG. 7 is a block diagram showing an essential part of an embodiment of the present invention, and FIG.
FIG. 9 and FIG. 9 are block diagrams showing another embodiment of the present invention, respectively. Explanation of code 1,2 ... Field memory, 3 ... Line memory, 4,5 ... Addition circuit (averaging circuit), 6 ... Mixing circuit, 7 ... Subtraction circuit,
8 ... Absolute value unit, 9 ... Inter-frame difference signal / motion amount converter,
10,34… Motion amount field memory, 11,35… Motion amount line memory, 12,17,19,26,33… Maximum value unit, 13,14… Time axis compression circuit, 15… Switch, 16… Motion Detection circuit, 18 ... Multiplier, 20, 21, 22, 23, 24, 25 ... Scan line interpolation circuit (signal processing circuit).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Katsumata, inventor 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Ltd. Home Appliances Research Laboratory, Hitachi, Ltd. (72) Inventor Nao Horiuchi, 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa (56) References JP-A-60-27287 (JP, A) JP-A-54-134515 (JP, A)

Claims (1)

[Claims] 1. A first interfield scanning line signal for a still image is created from an interlaced scanning television signal.
Second interpolating means and an interlaced scanning television signal to generate an inter-field interpolated scanning line signal for a moving image.
Interpolating means, and scanning line signal synthesizing means for synthesizing the inter-field interpolating scanning line signal and the intra-field interpolating scanning line signal, the interlaced scanning television signal and the scanning line signal synthesizing means. In a signal processing circuit for creating a sequential scanning signal from the combined interpolation scanning line signal, based on the inter-frame difference signal of the interlaced scanning television signal, the presence or absence of motion of an image represented by the television signal. Is detected and is output as motion information, and the motion detection output from the motion output synthesizing means described later is branched and taken in (1 field-0.5H) period and (1 field +
0.5H) after each delaying, the two are combined, the composite output is multiplied by a predetermined attenuation coefficient and output, and the motion information from the motion information detecting means and the attenuation delay means And a motion output synthesizing unit for synthesizing and synthesizing and outputting as the motion detection output. Motion adaptive signal processing circuit (where 1H indicates one horizontal scanning period)