JPH10191266A - Adaptive line insertion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce distortion owing to the difference of resolution in the boundary of moving areas and to reduce the deterioration of the sharpness of an image by controlling the characteristic of an inter-line insertion means in accordance with a motion index at the time of inserting the line through the use of the inter-field line insertion means. SOLUTION: When a TV signal (a) is supplied from outside, a movement detection part 2 obtains a difference between the TV signal delayed by a one frame delay circuit 1 and the signal (a) which is not delayed, and generates the movement detection signal MD of three bits from the difference. When the detection signal MD is 1-6, a line insertion switch part 8 selects the outputs of the inter-field line insertion parts 7b-7g. When the detection signal MD sequentially increases from '1' to '6', the switch part 8 sequentially selects the insertion parts 7b-7g in accordance with the value of the detection signal MD and inserts the inter-field line by sequentially using the filter of a narrow pass band. Thus, resolution can be changed stepwise by gradually changing the pass band of the filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a television signal,
The present invention relates to an adaptive line interpolation device that performs motion detection and performs a line interpolation process using a detected motion signal.

[0002]

2. Description of the Related Art Television (TV) signals have several systems having different numbers of lines and fields, for example, NTSC having a scanning line number / field frequency of 525/60.
There is a PAL system or the like, which is 625/50, and a conversion device between these systems is indispensable when exchanging programs or the like.

For example, when converting an NTSC system TV signal into a PAL system, the number of scanning lines is interpolated, and the number of scanning lines (lines) is interpolated into 525 scanning lines to reduce the number of scanning lines to 62.
The number is increased to five, and the number of fields per second is reduced to 50 by thinning out the fields.

A line interpolation method for performing such a line interpolation process is described in, for example, the documents "Japanese Patent Application Laid-Open No. Hei 1-309597 (Japanese Patent Application No. 63-139531) and Japanese Patent Application Laid-Open No. Hei 3-2806.
No. 81 (Japanese Patent Application No. 2-78731), Journal of the Institute of Television Engineers of Japan (Vol. 45, No. 12, 1991), p.
34 to P1543 "and the like.

[0005] Further, such line interpolation processing is performed by a TV.
Other than the signal format conversion, for example, a scan converter that converts the number of scanning lines and a field frequency to display a TV signal on a computer display, and a TV signal to a non-interlace format to improve the display quality of a TV monitor. It is also used in converters and the like.

As shown in FIG. 2, a typical conventional line interpolating apparatus has a motion detecting unit 12 for detecting the motion of an input TV signal and a scanning line (line) in the same field. Intra-field line interpolating unit 16 that interpolates scanning lines, inter-field line interpolating unit 17 that interpolates scanning lines based on scanning lines of different fields, and based on motion detected by motion detecting unit 12. And a line insertion weighted addition unit 18 for combining (weighted addition) the signals of the fields interpolated by the intra-field line interpolation unit 16 and the inter-field line interpolation unit 17.

In such a line interpolation device, the motion detecting section 12 includes a frame (previous frame) in the input signal delayed and supplied by the one-frame delay circuit 11 and the input signal a.
A motion detection signal is obtained from the difference between the middle frame (current frame).

[0008] The line interpolation weighting and adding unit 18 determines the motion of the image based on the motion detection signal from the motion detection unit 12, and when it is determined that the image is not moving, the inter-field line interpolation unit 17 When it is determined that the image is moving, the output of the intra-field line interpolation unit 16 is selected and output.

The inter-field line interpolation uses twice as many scanning lines as the intra-field line interpolation, so that equivalently twice the vertical resolution can be obtained. However, when the movement of the image between the fields is large, the (display) position of the moving object differs between adjacent fields, and if the field interpolation is performed as it is, the shape of the moving object is distorted, The sharpness of the moving object decreases. For this reason, the motion of the image is detected as described above, and the inter-field line interpolation and the intra-field line interpolation are adaptively switched.

[0010]

However, simply detecting the motion of an image and simply switching between inter-field line interpolation and intra-field line interpolation as described above requires a resolution at the boundary between a moving area and a still area. Becomes large, and distortion occurs at these boundaries.

For this reason, it is known that a motion detection result is represented by several bits, and a weighted addition of the intra-field line interpolation result and the inter-field line interpolation result is performed according to the value. Even if it was used, the distortion at the boundary of the moving region could not be satisfactorily removed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to provide an adaptive line interpolating apparatus capable of satisfactorily removing distortion at a boundary between moving regions.

[0013]

SUMMARY OF THE INVENTION An adaptive line interpolation device according to the present invention includes an intra-field line interpolation unit for performing an intra-field line interpolation on a video signal supplied from the outside, Detected by the inter-field line interpolation means capable of controlling characteristics when performing inter-field line interpolation, the motion detection means for obtaining the motion of the video signal and outputting a motion index corresponding to the obtained motion, and the motion detection means When performing line interpolation using either the intra-field line interpolation unit or the inter-field line interpolation unit, and performing the line interpolation using the inter-field line interpolation unit, Has line interpolation control means for controlling the characteristics of the inter-field line interpolation means according to the motion index.

The motion detecting means includes a delay means for delaying the video signal supplied from the outside by one frame, and a difference detecting means for obtaining a difference between the video signal delayed by the delay means and the video signal not delayed. And a configuration for generating a motion index based on the difference obtained by the difference detecting means.

[0015]

FIG. 1 is a block diagram showing a configuration of an adaptive line interpolation apparatus according to a preferred embodiment of the present invention. Such an adaptive line interpolation device, for example,
It is used when converting a television (TV) signal of the TSC system to the PAL system or when performing the reverse conversion.

As shown in FIG. 1, this adaptive line interpolation device receives an input NTSC television (T
V) One-frame delay circuit 1 that delays signal a by one frame, and T that is delayed by one-frame delay circuit 1
A motion detector 2 for comparing the V signal with the undelayed TV signal a to detect the motion of the image based on the TV signal, a one-field delay circuit 3 for delaying the input TV signal a by one field, And a line number converter 5 for converting the number of scanning lines of the TV signal delayed by the one-field delay circuit 3.

Further, the adaptive line interpolation device performs a line interpolation process using scanning lines (lines) in the same field based on the TV signal whose number of scanning lines has been converted by the line number conversion unit 4. In-field line interpolation processing unit 6
And seven inter-field line interpolation units 7a, 7b, 7c, 7d for performing a line interpolation process using the scanning lines in a plurality of fields from the line number conversion unit 4 and the line number conversion unit 5.
7e, 7f, and 7g, and controls switching of TV signals in which line interpolation has been performed by the intra-field line interpolation unit 6 and the inter-field line interpolation units 7a to 7g based on the motion detected by the motion detection unit 2. Line interpolation switching unit 8
And

FIG. 1 shows a configuration for interpolating a scanning line (line) only for a luminance component of a TV signal, for example. 1 includes a one-frame delay circuit 1 to a line interpolation switching unit 8 and the like, as in FIG.

The motion detector 2 calculates a difference (inter-frame difference signal) between a frame (previous frame) in the TV signal and a frame (current frame) in the TV signal a supplied by being delayed by the one-frame delay circuit 1. A motion detection signal with an accuracy of several bits is obtained.

The line number converters 4 and 5 receive the input TV.
The number of lines of the signal is converted into the number of lines of the system to be converted. For example, in the case of converting an NTSC system TV signal into a PAL system, one field scan line (312.5 lines) of the PAL system is formed based on one field scan line (262.5 lines) of the NTSC system. There is a need to. Actually, six scanning lines of the PAL system are created from five scanning lines of the NTSC system in a pseudo manner.

The actual conversion of the number of scanning lines is performed by the intra-field line interpolating unit 6 or the inter-field line interpolating units 7a to 7g, as will be described later. Since the scanning lines from the line number conversion unit 4 used for obtaining the insertion line are the same for every six scanning lines after the line number conversion, for example, j and j + 1 and j + 6 and j + 7 in FIG. Line number converter 4
Performs selection of a TV signal corresponding to a scanning line to be supplied to the intra-field line interpolation unit 6 or the inter-field line interpolation units 7a to 7g.

Similarly, in the inter-field line interpolation units 7a to 7g, the scanning lines from the line number conversion unit 5 used for obtaining the interpolation lines are, for example, j + 3 and j + 4 in FIG. Since the same becomes every six scanning lines after the line number conversion, the line number conversion unit 5 controls the scanning lines delayed by one field and supplied to the inter-field line interpolation units 7a to 7g. ing.

The in-field line interpolating unit 6 is composed of a digital filter constituted by, for example, a digital signal processor (DSP), and is supplied from the line number converting unit 4 as shown in a functional block diagram of FIG. It comprises n weighting units for weighting the TV signals corresponding to the respective scanning lines, and an adding unit for adding the outputs of the weighting units.

When the signal of each scanning line is supplied from the line number conversion unit 4 to the intra-field line interpolation unit 6 configured as described above, the scanning line i-1 of the NTSC system in FIG.
PAL scanning lines j and j + from i, i + 1, i + 2
1 are formed, and the scanning lines i, i + 1, i +
PAL scanning line j + 2 is formed from 2, i + 3,
NTSC scanning lines i + 1, i + 2, i + 3, i + 4
, A PAL scanning line j + 3 is formed, and the PAL scanning line i + 2, i + 3, i + 4, i + 5 is used as a PAL scanning line.
The scanning line j + 4 of the NTSC system is formed, the scanning line j + 5 of the PAL system is formed from the scanning lines i + 3, i + 4, i + 5, and i + 6 of the NTSC system, and the scanning lines i + 4, i of the NTSC system.
+5, i + 6, i + 7 form a PAL scanning line j + 6, and NTSC scanning lines i + 4, i + 5, i +
6, P + scanning line j + 7 is formed from i + 7.

In the intra-field line interpolating unit 6 configured as described above, the weight values of the respective weighting units are set so that the TV signal has the pass characteristic as shown in FIG.

Each of the inter-field line interpolators 7a to 7a
7g is, for example, a digital signal processor (DSP)
As shown in the functional block diagram of FIG. 7, 2n weighting units for weighting the TV signals of the respective scanning lines supplied from the line number conversion units 4 and 5 are provided. And an adder for adding the outputs of the respective weighting units. As shown in FIGS. 8A to 8C, the inter-field line interpolation units 7a to 7g configured as described above have respective weighting units so that the TV signals have different pass characteristics. A weight value has been set. As shown in FIG. 8A, the inter-field line interpolation unit 7a has a pass band twice that of the above-described intra-field line interpolation unit 6, and has the other inter-field line interpolation units 7b to 7b.
7g, as shown in FIGS. 7B and 7C, the band is gradually narrowed from the pass band of the inter-field line interpolation unit 7a to the pass band of the intra-field line interpolation unit 6. I have.

Further, the line interpolation switching section 8 performs the above-mentioned intra-field line interpolation section 6 and inter-field line interpolation sections 7a to 7 based on the motion detection signal from the motion detection section 2.
Switching or combining of the outputs of d is performed.

Hereinafter, the operation of the adaptive line interpolation device configured as described above will be described. When the TV signal a is supplied from the outside, the motion detection unit 2 calculates a difference between the TV signal delayed by the one-frame delay circuit 1 and the undelayed TV signal a, and from this difference (inter-frame difference signal). A 3-bit motion detection signal MD is generated. The motion detection signal MD is set to 0 when the inter-frame difference signal is small and the image based on the TV signal can be regarded as substantially a still image, and the inter-frame difference signal is large.
If the image based on the TV signal can be definitely regarded as a moving image, the value is set to 7. If the TV signal is between these two states, the motion detector 2
Sets the motion detection signal MD to a value from 1 to 6 according to the level of the inter-frame difference signal.

For the detection of such a motion detection signal MD, for example, a range of the difference between the value of the motion detection signal MD and the delayed TV signal a corresponding to this value and the undelayed TV signal a is set in advance. Alternatively, the determination may be made by determining which value of the motion detection signal MD corresponds to the obtained difference.

When the TV signal is a moving image, distortion is generated around the moving object when inter-field line interpolation is performed.
Sharpness decreases. For this reason, the line interpolation switching unit 8
If the TV signal is definitely a moving image (if MD = 7), the output of the intra-field line interpolation unit 6 in which the intra-field line interpolation has been performed is selected, and the TV signal is a still image. In a certain case (when MD = 0), the inter-field line interpolation unit 7a in which the inter-field line interpolation is performed
Select the output of

When the motion detection signal MD is 1 to 6,
The line interpolation switching unit 8 selects the output of each of the inter-field line interpolation units 7b to 7g. These inter-field line interpolation units 7b to 7g perform inter-field line interpolation using the filter having the pass band set as described above. That is, MD = 1
, The pass band of the filter used by the inter-field line interpolation unit 7b is slightly narrower than the filter used by the inter-field line interpolation unit 7a, and MD = 6.
The pass band of the filter used by the inter-field line interpolation unit 7g selected in the case of (1) is slightly wider than the pass band of the filter used by the intra-field line interpolation unit 6. The remaining inter-field line interpolation units 7c to 7f
Are gradually narrowed between the pass bands of the filters of the inter-field line interpolation units 7b and 7g.

Therefore, the motion detection signal MD sequentially changes from 1 to 6
, The line interpolation switching unit 8 sequentially switches the inter-field line interpolation unit 7 according to the value of the motion detection signal MD.
b to 7g are selected, and inter-field line interpolation is sequentially performed using a filter having a narrow pass band.

As described above, by gradually changing the pass band of the filter for performing the inter-field line interpolation based on the value of the motion detection signal MD detected by the motion detection unit 2, the image in the image based on the TV signal can be changed. The change in resolution at the boundary between the still region and the moving region can be made stepwise, and distortion due to the difference in resolution at the boundary between moving regions, which has conventionally been a problem, can be reduced. Therefore, with this adaptive line interpolation device, it is possible to reduce the deterioration of image sharpness.

In the above description, a plurality of inter-field line interpolation units 7a to 7g using filters having different pass bands according to the degree of motion (motion detection signal MD).
Has been described, but for example, an inter-field line interpolation unit using a DSP, a digital filter
Only one filter may be provided, and different passbands may be realized by switching the coefficients of the filter according to the motion detection signal MD.
In addition, various changes can be made within the technical idea of the present invention.

[0035]

According to the adaptive line interpolation apparatus according to the present invention,
The line interpolation control means performs the line interpolation using either the intra-field line interpolation means or the inter-field line interpolation means according to the motion index from the motion detection means, and the inter-field line interpolation means. In the case of performing line interpolation using, by controlling the characteristics of the inter-field line interpolation means according to the motion index, the change in resolution at the boundary between the still region and the moving region in the image based on the video signal is calculated. This can be performed stepwise, and distortion due to a difference in resolution at the boundary of a moving region, which has conventionally been a problem, can be reduced. Therefore, it is possible to reduce the deterioration of the sharpness of the image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an adaptive line interpolation device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional adaptive line interpolation device.

FIG. 3 is a diagram for describing an intra-field line interpolation process in the adaptive line interpolation device according to the first embodiment of the present invention.

FIG. 4 is a diagram for explaining an inter-field line interpolation process in the adaptive line interpolation device.

FIG. 5 is a block diagram illustrating a configuration of an intra-field line interpolation unit included in the adaptive line interpolation device.

FIG. 6 is a diagram showing a pass band of the intra-field line interpolation unit. .

FIG. 7 is a block diagram illustrating a configuration of an inter-field line interpolation unit included in the adaptive line interpolation device.

FIG. 8 is a diagram showing a pass band of the inter-field line interpolation unit.

[Explanation of symbols]

1 1 frame delay circuit, 2 motion detection circuit, 3
1 field delay circuit, 4, 5 line number conversion circuit,
6 Line interpolation section within field, 7 Line interpolation section between fields, 8 Line interpolation switching section

Claims (4)

[Claims] 1. An intra-field line interpolating means for inter-field line interpolating for a video signal supplied from the outside, and a characteristic when performing inter-field line interpolating for the video signal can be controlled. Inter-field line interpolation means, a motion detection means for obtaining the motion of the video signal, and outputting a motion index corresponding to the obtained motion, according to the motion index detected by the motion detection means,
When performing line interpolation using either the intra-field line interpolation means or the inter-field line interpolation means, and performing line interpolation using the inter-field line interpolation means, A line interpolation control means for controlling characteristics of the inter-field line interpolation means. 2. The motion detecting means according to claim 1, wherein said motion detecting means delays a video signal supplied from outside by one frame, and a difference detecting means for obtaining a difference between the video signal delayed by said delay means and a video signal which is not delayed. 2. The adaptive line interpolation device according to claim 1, further comprising: means for generating the motion index based on the difference obtained by the difference detection means. 3. The inter-field line interpolating means includes a plurality of digital filters for interpolating inter-field lines having different characteristics, and the line interpolating control means includes a plurality of digital filters based on the motion index. 3. The adaptive line interpolation device according to claim 1, wherein an output of the filter is selected. 4. The inter-field line interpolation means includes a digital filter capable of controlling a pass band, and the line interpolation control means controls a pass band of the digital filter based on the motion index. The adaptive line interpolation device according to claim 1 or 2, wherein: