JP3389984B2 - Progressive scan conversion device and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a progressive scan conversion apparatus and method for converting an interlaced video signal into a progressive scan video signal.

[0002]

2. Description of the Related Art Standard television signals such as NTSC signals and high-definition signals are interlaced (interlaced scan) signals. FIG. 5 is a diagram showing a scanning line structure,
(A) shows an interlaced signal, (b) shows a progressive (sequential scanning) signal, and (c) shows a signal obtained by converting the interlaced signal into a progressive signal by scanning line interpolation. The progressive signal may also be referred to as a non-interlaced signal. In FIG. 5, a circle indicates a scanning line, and a cross indicates an interpolated scanning line.

In FIG. 5, the vertical direction V is the vertical direction of the screen, and the horizontal direction t is the time direction. As shown in FIG. 5A, the interlaced signal is composed of two fields in which one frame is shifted in the time and vertical directions. On the other hand, the progressive signal is shown in FIG.
As shown in, there is no deviation in the scanning line structure. In the interlaced signal, when the number of high frequency components in the vertical direction of the image increases, there is interlaced interference such as line flicker. On the other hand, with progressive signals, there is no interlace interference.

Therefore, as shown in FIG. 5C, by interpolating the scanning lines of the portion thinned by the interlacing with the peripheral scanning lines and converting them into a progressive signal,
There are processing methods to remove interlace interference. Such a processing method is called progressive scanning conversion or double-density conversion.

Conventionally, scanning line interpolation for progressive scanning conversion and double-dense conversion is performed by motion adaptive processing. That is, as shown in FIG. 6, when the image is stationary, a new scanning line is generated by performing inter-field interpolation using the average value of the pixels A and B in the preceding and following fields as a new pixel Q indicated by x. To do. When the image is moving, a new scanning line is generated by performing in-field interpolation using the average value of the upper and lower pixels C and D as a new pixel Q indicated by x. Therefore, when the image is still, good conversion image quality with less aliasing distortion and high resolution can be obtained.
When the image is moving, the converted image quality is deteriorated due to many aliasing distortion and low resolution.

By the way, when the input signal to be converted into the progressive scanning signal is the signal converted into the interlace by the 3-2 pull-down, a method different from the motion adaptive processing is adopted to make the image even when the image moves. A good converted image quality can be obtained. The 3-2 pulldown is a frame rate conversion as shown in FIG. Specifically, film data (sequential scanning signals) A, B, C, D, etc. of a movie of 24 frames / sec.
Interlaced signals a, a ', a, b', such as TSC system
It is used as a method for converting into b, c ', c ... Although there is also a frame rate conversion called 2-2 pulldown, here, 3-2 pulldown will be described as a representative.

As shown in FIG. 7, 3-2 pulldown is
The image that was originally one frame is distributed to three or two fields. Therefore, if the 3-2 pattern of the input signal converted into the interlace by the 3-2 pulldown is known, the field interpolation can be performed with the adjacent field generated from the image of the same one frame regardless of the stillness or motion of the image. It can be done and converted to progressive scan. 6
When an interlace signal of 0 field / sec is converted into progressive scan, 60 frame / sec of progressive scan signals A, A, A,
B, B, C, C, C ...

The interlaced signals a, a ', a,
In b ′, b, c ′, c, the presence or absence of the code “′” indicates the difference between the odd field and the even field. For example, the field without the code “′” is the odd field, The field with the symbol "'" is an even field. Therefore, for example, the field a and the field a ′ are the same image, but their scanning lines are deviated from each other.

Similar to the inter-field interpolation shown in FIG. 6, the field interpolation generates a new scan line by setting the pixel A in the previous field or the pixel B in the subsequent field as a new pixel Q, so that aliasing distortion is generated. Good conversion image quality with less resolution and higher resolution can be obtained.

A method for reconverting a signal converted into interlace by 3-2 pulldown into a progressive scanning signal is described in, for example, US Pat. No. 4,876,596 and US Pat. No. 4,98.
2,280. U.S. Pat.No. 4,876,596
According to the specification, if the transmitting side sends in advance as a code which field is allocated to 3 fields and which field is allocated to 2 fields, this code will be received. By reading on the side and using the appropriate field, 60
The original film data can be reproduced by progressive scanning of frames / second.

According to US Pat. No. 4,982,280, a pattern detector for detecting a 3-2 pattern of 3-2 pulldown is provided on the receiving side, and by using an appropriate field, 60 frames / sec. The original film data can be reproduced by the sequential scanning of. These methods require either a clear specification of 3-2 pulldown or the ability to detect this pattern.

Another method for reconverting a signal converted into interlace by 3-2 pulldown into progressive scanning is disclosed in Japanese Patent Application Laid-Open No. 8-307837. According to JP-A-8-307837, the input signal is 3-
When the signal is converted into interlace by 2 pulldown, each field has the same 1 as shown in FIG.
Since the field generated from the image of the frame always exists in the adjacent field, the field generated from the image of the same one frame is detected by detecting the movement between the fields, and the sequential scanning of 60 frames / second is performed. The original film data can be played with.

According to this method, it is not necessary to insert a code for identifying the 3-2 pulldown on the transmitting side, and also on the receiving side, a decoder for decoding the code is provided or a pattern detector is used to detect the 3-2 pulldown. -No need to detect -2 patterns at the field level.

Here, an outline of the progressive scan conversion device described in Japanese Patent Laid-Open No. 8-307837 will be described with reference to FIG. As shown in FIG. 8, the progressive scan conversion device has two
Two field delays (field delays) 102,
103 and a processor 104. Input terminal 10
The video signal input from the 1 is a field delay unit 102.
And to the processor 104. The output of the field delay device 102 is input to the field delay device 103 and the processor 104. The output of the field delay device 103 is input to the processor 104. The video signal converted into progressive scanning by the processor 104 is output from the output terminal 105.

In FIG. 8, assuming that the field held in the field delay unit 102 is the current field, the field input from the input terminal 101 is located after the current field in time, so it is set as the rear field. The field held in the delay device 103 is located in front of the current field in time, and thus is set as the previous field.

Using the progressive scan conversion device shown in FIG.
When the signal converted into interlace by the 3-2 pulldown is converted back into the progressive scan, the processor 104 generates the first motion signal M1 from the comparison between the current field and the previous field, and the current field and the next field. To generate a second motion signal M2. At this time,
Since the input signal is interlaced, the pixel array is as shown in FIG. The first motion signal M1 corresponding to the pixel c is detected by using the minimum absolute value of the value (pixel c-pixel a) and the value (pixel c-pixel b). That is, M1 = MIN (| pixel c-pixel a |, | pixel c-pixel b
|), And the motion signal M1 is the smaller value of the value | pixel c-pixel a | and the value | pixel c-pixel b |.

Similarly, the second motion signal M2 is detected by using the minimum absolute value of the values (pixel c-pixel d) and (pixel c-pixel e). That is, M2 = MIN (| pixel c-pixel d |, | pixel c-pixel e
|), And the motion signal M2 is a smaller one of the value | pixel c-pixel d | and the value | pixel c-pixel e |.

When the input signal is a signal converted into interlace by 3-2 pulldown, as shown in FIG. 7, in each field, a field generated from an image of the same one frame always exists in an adjacent field. . Therefore, at least one of the motion signals becomes zero except for the high spatial frequency pattern. That is, the motion signal k = MIN, which is the minimum value of the first motion signal M1 and the second motion signal M2.
(M1, M2) becomes close to zero.

The threshold value T for the motion signal k is set so as to reduce erroneous determination due to noise in the image. The motion signal k is smaller than the threshold value T (k <
If T), the processor 104 determines that the signal has been converted by 3-2 pulldown, and outputs the signal converted into progressive scanning by field interpolation from the output terminal 105. At this time, whether to select the previous field or the subsequent field depends on whether the motion signal M1 or M is selected.
It depends on which of the two is smaller. For example, M1 <M
If 2, field interpolation is performed using the previous field. On the other hand, if the motion signal k is larger than the threshold value T (k> T), the processor 104 determines that the signal is not a signal converted by the 3-2 pulldown, and another method using the motion signal k (for example, motion It is converted into a progressive scanning signal by an adaptive process or the like).

[0020]

As shown in FIG. 9, since the input signal is an interlaced signal, there is no pixel in the preceding and following fields at the same position as the pixel in the current field.
Therefore, the upper and lower lines are used to detect the motion signals M1 and M2. In this motion detection, when the two fields to be compared are images generated from the same frame, the difference between the upper and lower pixels, that is, the output result of the vertical high-pass filter is obtained. Therefore, even if the image is generated from the same frame in the previous field with respect to the current field, if the pattern has a large vertical high frequency component,
Even images generated from frames in which the subsequent fields are different may satisfy M1> M2.

Similarly, even if an image generated from the same frame in two fields before and after the current field is a horizontal edge portion having a large vertical high frequency component,
The motion signals M1 and M2 do not become zero, and the motion signal k may become larger than the threshold value T. In particular, the vertical high-frequency component is large in the character portion, and the motion signal k tends to be large.

As described above, the motion signal M using the minimum absolute value of the values (pixel c-pixel a) and (pixel c-pixel b).
In the comparison of two motion signals of 1 and the motion signal M2 using the minimum absolute value of the values (pixel c-pixel d) and (pixel c-pixel e), the same one frame existing in the adjacent field is compared. The field generated from the image cannot be correctly determined. Therefore, in the conventional progressive scan conversion device, field interpolation is performed in the wrong field,
There is a problem that the image quality is deteriorated by performing motion adaptive processing.

Further, in the conventional progressive scan conversion apparatus, in the case of a video signal including many horizontal edge portions having a large vertical high frequency component such as Japanese subtitles of a movie, or by the 3-2 pulldown or 2-2 pulldown, There is a problem that the image quality may be deteriorated even in the case of a video signal in which an image converted into a race and a normal 60 field / sec image are mixed.

The present invention has been made in view of the above problems, and a video signal converted into interlace by 3-2 pulldown or 2-2 pulldown can be converted into progressive scan without deterioration of image quality. It is an object to provide a scan conversion device and method. Also, in the case of a video signal including many horizontal edge parts with large vertical high frequency components such as Japanese subtitles of movies, images converted to interlace by 3-2 pulldown or 2-2 pulldown and normal 60 fields It is an object of the present invention to provide a progressive scan conversion apparatus and method capable of satisfactorily converting to progressive scan without deterioration in image quality even in the case of a video signal in which images of 1 / second are mixed.

[0025]

In order to solve the above-mentioned problems of the prior art, the present invention provides (1) a progressive scan conversion device for converting an interlaced video signal into a progressive scan video signal. An in-field interpolating circuit (4) for generating an in-field interpolating signal from scanning lines spatially positioned above and below the interpolated scanning line in the field, the in-field interpolating signal, and the current field in time. The first matching representing the matching between the current field and the subsequent field is generated by generating the difference of the low frequency component in the vertical direction with respect to the subsequent field signal, which is the scanning line at the same position as the interpolated scanning line. Means (601, 604, 606) for generating a signal, the inter-field interpolated signal, and the current field, which is positioned before in time.
A second matching signal representing the matching between the current field and the previous field is generated by generating a difference of a low frequency component in the vertical direction with respect to the preceding field signal which is a scanning line at the same position as the interpolation scanning line. Means (60
2, 605, 608) and a difference between the first matching signal and the second matching signal to generate a first mixing coefficient of the rear field signal and the front field signal. (609) and a first mixing circuit (5) for mixing the rear field signal and the front field signal to generate a field interpolation signal according to the first mixing coefficient. (2) In a progressive scan conversion method for converting an interlaced video signal into a progressive scan video signal, a progressive scan converter characterized in that A step of generating an intra-field interpolation signal from scan lines located above and below, the intra-field interpolation signal, and the temporal position behind the current field,
A first matching signal representing matching between the current field and the subsequent field is generated by generating a difference of a low frequency component in the vertical direction with respect to the subsequent field signal which is a scanning line at the same position as the interpolation scanning line. Step, the intra-field interpolated signal, and the difference in the low frequency component in the vertical direction between the previous field signal which is a scanning line located temporally before the current field and located at the same position as the interpolated scanning line, Generating a second matching signal representing the matching of the current field and the previous field, and generating the difference between the first matching signal and the second matching signal, Generating a first mixing coefficient of the field signal and the previous field signal; There is provided a progressive scanning conversion method characterized by comprising the steps of generating a field interpolated signal by mixing the subsequent field signal and the previous field signal.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION A progressive scan conversion apparatus and method according to the present invention will be described below with reference to the accompanying drawings. Figure 1
1 is a block diagram showing an embodiment of a progressive scan conversion device of the present invention, FIG. 2 is a diagram for explaining a progressive scan conversion device and method of the present invention, and FIG. 3 is a concrete example of the matching detection circuit 6 in FIG. FIG. 4 is a block diagram showing an example of the configuration, and FIG. 4 is a diagram showing mixing characteristics of the mixing circuits 5 and 7 in FIG.

In FIG. 1, the interlaced video signal input from the input terminal 1 is input to the field delay device 2, the mixing circuit 5, and the matching detection circuit 6. The field delay unit 2 delays the input signal by a time corresponding to one field, and the delayed signal is delayed by the field delay unit 3,
Input to the inter-field interpolation circuit 4 and the double speed conversion circuit 8.
Like the field delay device 2, the field delay device 3 delays the input signal by a time corresponding to one field, and inputs the delayed signal to the mixing circuit 5 and the matching detection circuit 6.

The inter-field interpolating circuit 4 interpolates a scanning line which does not exist in the input field. Therefore, the intra-field interpolating signal is generated by adding the scanning lines above and below the interpolated scanning line, and the intra-field interpolation signal is generated. The interpolation signal is input to the matching detection circuit 6 and the mixing circuit 7.

The signal supplied from the intra-field interpolation circuit 4 to the matching detection circuit 6 is the current intra-field interpolation signal generated from the scanning lines spatially above and below the interpolated scanning line in the current field. The signal supplied from the input terminal 1 to the matching detection circuit 6 is a field located temporally behind the current field. If a scan line signal at the same position as the interpolated scan line of this field is used for scan line interpolation, this signal becomes an interpolated interpolation signal of a field after the interpolated signal of the current field. It is called a field interpolation signal.

Similarly, the signal supplied from the field delay unit 3 to the matching detection circuit 6 is a field located temporally before the current field. If a scanning line signal at the same position as the interpolated scanning line in this field is used for scanning line interpolation, this signal becomes an interpolation interpolation signal in the previous field rather than the interpolation signal in the current field. It is called a field interpolation signal.

Virtually three frame images can be obtained by the above three interpolation signals including the current field interpolation signal, the rear field interpolation signal, and the front field interpolation signal.

Of the three frame images, the first frame image is a frame image interpolated only with the information of the current field. The second frame image is a frame image interpolated by the information of the subsequent field. The third frame image is a frame image interpolated with the information of the previous field. When the input signal is a signal converted into interlace by 3-2 pulldown, the original frame image is reproduced in either the second frame image or the third frame image.

FIG. 2A shows frame rate conversion by 3-2 pulldown similar to FIG. For example, the field shown in FIG. 2A is the current field.
At this time, the second frame image is b + c '≠ B,
The third frame image is b '+ b = B. Therefore, the vertical low band component of the second frame image and the vertical low band component of the third frame image are compared with the vertical low band component of the first frame image, respectively. Comparing the two images with the vertical low-frequency components, the influence of the vertical high-frequency components can be reduced even if the pattern has a large vertical high-frequency component. Then, by checking the degree of matching, it is possible to determine which of the second frame image and the third frame image reproduces the original frame image.

This determination is effective if the field generated from the same one-frame image always exists in the adjacent field. Therefore, 30 shown in FIG.
60 sequential scanning signals such as film data at frame / second
Even a signal converted into interlace by 2-2 pulldown used as a method for converting into an interlaced signal such as field / second NTSC system,
You can check the degree of matching in the same way. For example, if the field shown in FIG. 2B is the current field, the second frame image is c + c ′ = C,
The third frame image has b ′ + c ≠ C.

Here, an example of a specific configuration of the matching detection circuit 6 in FIG. 1 for comparing the above-mentioned three frame images will be described with reference to FIG. In FIG. 3, the input terminal 1
The post-field interpolation signal, which is the input signal that is input more, is input to the subtraction circuits 601 and 603. The current intra-field interpolation signal from the intra-field interpolation circuit 4 is input to the subtraction circuits 601 and 602. Field delay device 3
The previous field interpolation signal from
603 is input.

The subtraction circuit 601 generates a difference signal between the current field interpolated signal and the post field interpolated signal, and the difference signal is a vertical low pass filter (hereinafter, vertical LPF).
Input to 604. The subtraction circuit 602 generates a difference signal between the current field interpolation signal and the previous field interpolation signal, and inputs the difference signal to the vertical LPF 605. Vertical L
The PFs 604 and 605 suppress high frequency components in the vertical direction of the input difference signal.

The output of the vertical LPF 604 is an absolute value conversion circuit 6.
06, the absolute value is converted to an absolute value, and the subtraction circuit 6 is used as a post-field matching signal (first matching signal).
09 and the minimum value selection circuit 610. Vertical LP
The output of F605 is input to the absolute value conversion circuit 608 and converted into an absolute value, and is input to the subtraction circuit 609 and the minimum value selection circuit 610 as a previous inter-field matching signal (second matching signal). Subtraction circuit 601 and vertical LPF 6
04 and the absolute value conversion circuit 606 constitute means for generating a first matching signal indicating matching between the current field (first frame image) and the subsequent field (second frame image). In addition, the subtraction circuit 602 and the vertical LPF
605 and the absolute value conversion circuit 608 determine the current field (first frame image) and the previous field (third frame image).
It constitutes a means for generating a second matching signal representing the matching with.

The subtraction circuit 609 subtracts the rear inter-field matching signal from the front inter-field matching signal,
The matching signal M is output from the output terminal 611. This matching signal M is input to the mixing circuit 5 in FIG. 1 as a mixing coefficient.

The mixing circuit 5 is, as shown in FIG.
According to the magnitude of the input matching signal M, the rear field interpolation signal input from the input terminal 1 and the front field interpolation signal input from the field delay unit 3 are adaptively mixed. When the matching signal M = 0,
The mixing ratio is 0.5 (50:50). That is, the mixing circuit 5 uniformly mixes the rear field interpolation signal and the front field interpolation signal.

If the matching signal M is positive, the number of post-field interpolation signals is increased as the absolute value of the matching signal M increases, and if the matching signal M is negative,
As the absolute value of the matching signal M increases, the number of previous field interpolation signals increases. If the matching signal M exceeds a predetermined absolute value, only one of the rear field interpolation signal and the front field interpolation signal is used.

For example, the fields shown in FIG.
The matching signal M is always zero. 24 frames /
When the motion is small on the film data of the second movie or the like (frames A, B, C, and D are the same image), the front-field matching signal and the rear-field matching signal have the same value. The matching signal M is close to zero in other fields. When converting fields other than fields to progressive scan,
In the conventional technique, either the front field interpolation signal or the rear field interpolation signal is selected according to the 3-2 pattern. For example, when converting the field of FIG. 2A to progressive scanning, the field was interpolated.

On the other hand, in the present invention, as shown in FIG. 4 (a), since the two interpolation signals are mixed according to the size of the matching signal M, it is different from the previous field interpolation signal which is originally a different frame. The noise with respect to the time direction is reduced by taking the average with the post-field interpolation signal. For example, when converting the fields of FIG. 2A to progressive scan, field-to-field averaging, or interframe interpolation, is performed.

If the input signal is a signal converted into an interlace by the 3-2 pulldown shown in FIG. 2A or the 2-2 pulldown shown in FIG. 2B, the input signal is output from the mixing circuit 5. It is possible to obtain the optimum field interpolation signal for conversion into progressive scanning.

However, due to screen composition, etc., 3-2
When a signal in which a signal converted into interlace by pull-down or 2-2 pull-down and a normal 60 field / second signal are mixed is input, the normal 60 field / second image part, especially moving image Therefore, the optimum field interpolation signal cannot be obtained. This is 3
-2 pulldown or 2-2 pulldown is a prerequisite for matching detection for progressive scan conversion of a signal converted to interlace, a condition that a field generated from an image of the same one frame exists in an adjacent field. This is because it does not apply to a normal moving image portion of 60 fields / second.

Therefore, the present invention is configured as follows. Returning to FIG. 3 again, the subtraction circuit 603 generates a difference signal between the post-field interpolation signal input from the input terminal 1 and the front-field interpolation signal input from the field delay unit 3. This is to detect a normal 60 field / sec moving image portion. The output of the subtraction circuit 603 is input to the absolute value conversion circuit 607, converted into an absolute value, and input to the minimum value selection circuit 610 as an inter-frame matching signal (third matching signal). Subtraction circuit 60
3 and the absolute value conversion circuit 607 constitute means for generating a third matching signal representing matching between the rear field (second frame image) and the front field (third frame image).

The minimum value selection circuit 610 receives the input third signal.
Inter-frame matching signal which is the matching signal of
The signal showing the minimum value is selected from the rear inter-field matching signal which is the first matching signal and the front inter-field matching signal which is the second matching signal, and the motion signal K is output from the output terminal 612. This motion signal K is input to the mixing circuit 7 in FIG. 1 as a mixing coefficient.

The mixing circuit 7, as shown in FIG.
The field interpolation signal input from the mixing circuit 5 and the current field interpolation signal input from the field interpolation circuit 4 are adaptively mixed according to the magnitude of the input motion signal K. The larger the motion signal K, the more the current field interpolation signal and the smaller the field interpolation signal. If the motion signal K is zero, only the field interpolation signal, that is, the mixing ratio of the current field interpolation signal and the field interpolation signal is set to 0: 100. If the motion signal K exceeds a predetermined value, only the current intrafield interpolation signal, that is, the mixing ratio of the current intrafield interpolation signal and the field interpolation signal is set to 100: 0.

The reason for comparing the three matching signals of the inter-frame matching signal, the post-field matching signal and the front inter-field matching signal in the minimum value selection circuit 610 is to obtain the motion signal K correctly.
In a natural image, the motion signal K can be obtained by comparing two matching signals of a rear inter-field matching signal and a front inter-field matching signal. In a moving image of 60 fields / sec, since each field image is different, the values of the post-field matching signal and the front-field matching signal are large. In a still image of 60 fields / sec, since each field image is the same, the value of both the post-field matching signal and the front-field matching signal becomes zero.

However, in a character image portion such as a Japanese subtitle of a movie, which includes many horizontal edge portions with large vertical high frequency components, the values of the rear-field inter-field matching signal and the front-field inter-field matching signal are still even in a still image. It is not completely zero. There is also a method of reducing the influence of the character image portion by providing a predetermined threshold value T for the motion detection signal K, but if the threshold value T is made too large, true motion information will be lost, which is not effective.

On the other hand, the inter-frame matching signal has a magnitude of one-frame difference and is not affected by the magnitude of the vertical high frequency component, and can capture only the time variation. That is, the inter-frame matching signal becomes zero even in the character image portion where the values of the rear inter-field matching signal and the front inter-field matching signal do not become zero despite the still image. According to the present invention, since the inter-frame matching signal is used, matching is not erroneously determined even in the case of a video signal including many horizontal edge portions having large vertical high frequency components such as Japanese subtitles of a movie.

In FIG. 1, the output of the mixing circuit 7 is input to the double speed conversion circuit 8 as a final interpolation signal. The double speed conversion circuit 8 converts the current line signal input from the field delay device 2 and the interpolation signal input from the mixing circuit 7 alternately at a speed twice that of the input signal, thereby converting the current line signal into a sequential scanning signal. This progressive scanning signal is output from the output terminal 9.

With the above configuration, 3-2 pulldown and 2
A video signal converted into interlace by -2 pulldown can be converted into progressive scanning without image quality deterioration.
In the case of a video signal that contains many horizontal edge parts with large vertical high frequency components such as Japanese subtitles of movies, images converted to interlace by 3-2 pulldown or 2-2 pulldown and normal 60 fields / second Even in the case of a video signal in which the image of (1) and (2) are mixed, it is possible to favorably convert to progressive scanning.

[0053]

As described in detail above, the progressive scan conversion apparatus and method of the present invention generate the intra-field interpolation signal from the scan lines spatially above and below the interpolated scan line in the current field. , Generating a low frequency component difference in the vertical direction between the interpolated signal in the field and the rear field signal that is a scanning line located temporally behind the current field and located at the same position as the interpolated scanning line. To generate a first matching signal representing matching between the current field and the subsequent field, and to scan the inter-field interpolated signal and the scan line located temporally before the current field and at the same position as the interpolated scan line. A second matching signal representing the matching between the current field and the previous field is generated by generating the difference of the low frequency component in the vertical direction with respect to the previous field signal. Form, the first matching signal and the second
By generating a difference between the rear-field signal and the front-field signal, and generating a first mixing coefficient between the rear-field signal and the front-field signal, and mixing the rear-field signal and the front-field signal according to the first mixing coefficient. Since the field interpolation interpolation signal is generated by doing so, field interpolation is not performed in the wrong field, and the video signal converted into interlace by 3-2 pulldown or 2-2 pulldown does not deteriorate in image quality. It can be converted into progressive scan.

Further, by generating the difference between the rear field signal and the front field signal, a third matching signal representing matching between the rear field signal and the front field signal is generated, and the first matching signal and the second matching signal are generated. A second mixing coefficient of the inter-field interpolation signal and the field interpolating interpolation signal is generated by selecting the signal having the minimum value from the matching signal and the third matching signal, and the second mixing coefficient is generated according to the second mixing coefficient. The field interpolation signal and the field interpolation signal are mixed to generate the interpolation signal, so there is no need to perform field interpolation or motion adaptation processing in the wrong field, and In the case of a video signal containing many horizontal edge parts with large vertical high frequency components such as word subtitles, or by 3-2 pulldown or 2-2 pulldown Even if the converted image in Ntaresu the normal 60 fields / second image of the video signal are mixed, it can be converted into good progressive scan without image degradation.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining the present invention.

3 is a block diagram showing an example of a specific configuration of a matching detection circuit 6 in FIG.

FIG. 4 is a diagram showing mixing characteristics of mixing circuits 5 and 7 in FIG.

FIG. 5 is a diagram showing various scanning line structures.

FIG. 6 is a diagram showing inter-field interpolation and intra-field interpolation.

FIG. 7 is a diagram for explaining 3-2 pulldown.

FIG. 8 is a block diagram showing a conventional example.

FIG. 9 is a diagram for explaining a conventional problem.

[Explanation of symbols]

A few field delays 4 Inter-field interpolation circuit 5,7 mixed circuit 6 Matching detection circuit 8x speed conversion circuit 601-603,609 Subtraction circuit 604,605 Vertical low-pass filter 606-608 Absolute value conversion circuit 610 Minimum value selection circuit

Claims (6)

(57) [Claims] 1. A progressive scan conversion device for converting an interlaced video signal into a progressive scan video signal, wherein an intrafield interpolation signal is generated from a scan line spatially above and below an interpolated scan line in a current field. The in-field interpolating circuit to be generated, the in-field interpolating signal, and the in-field interpolating signal, which is located in a temporally rearward position with respect to the current field and is lower in the vertical direction with respect to the subsequent field signal which is a scanning line at the same position as the interpolated scanning line Means for generating a first matching signal representing the matching of the current field and the subsequent field by generating the difference of the frequency component; the intra-field interpolated signal; , By generating a difference of a low frequency component in the vertical direction with respect to the preceding field signal which is a scanning line at the same position as the interpolated scanning line, Means for generating a second matching signal representing the matching between the field and the previous field; and the difference between the first matching signal and the second matching signal to generate the difference between the rear field signal and the front field. Means for generating a first mixing coefficient with the signal, and first mixing for mixing the rear field signal and the front field signal according to the first mixing coefficient to generate a field interpolation signal A progressive scan conversion device comprising: a circuit. 2. A third representing a matching between the rear field signal and the front field signal by generating a difference between the rear field signal and the front field signal.
Means for generating the matching signal, and selecting the signal showing the minimum value from the first matching signal, the second matching signal, and the third matching signal, whereby the inter-field interpolation signal and the field Means for generating a second mixing coefficient with the interpolated interpolation signal; and a means for generating an interpolation signal by mixing the intra-field interpolated signal and the field interpolated interpolated signal according to the second mixing coefficient. 2. The progressive scan conversion apparatus according to claim 1, wherein the progressive scan conversion apparatus comprises two mixing circuits. 3. The first mixing circuit mixes the rear field signal and the front field signal at a mixing ratio of 50:50 when the first mixing coefficient is zero, and the first mixing circuit When the coefficient is positive, the mixing ratio of the rear field signal is increased as the absolute value of the first mixing coefficient is increased, and when the first mixing coefficient is negative, the absolute value of the first mixing coefficient is increased. 3. The mixing ratio of the preceding field signal is increased as it increases.
The progressive scan conversion device described in. 4. The second mixing circuit mixes the intra-field interpolation signal and the inter-field interpolation signal at a mixing ratio of 0: 100 when the second mixing coefficient is zero.
3. The progressive scan conversion apparatus according to claim 2, wherein as the second mixing coefficient increases, the mixing ratio of the intra-field interpolation signal is increased and the mixing ratio of the field interpolation signal is decreased. 5. A progressive scan conversion method for converting an interlaced video signal into a progressive scan video signal, wherein an intra-field interpolation signal is generated from a scan line spatially above and below an interpolated scan line in a current field. The step of generating, the intra-field interpolated signal, of the low frequency component in the vertical direction of the rear field signal, which is a scanning line located at the same time as the interpolated scanning line, and which is located temporally behind the current field. Generating a first matching signal representing matching between a current field and a subsequent field by generating a difference; the intra-field interpolated signal; By generating the difference in the low frequency component in the vertical direction from the previous field signal, which is a scan line at the same position as the interpolation scan line, the current field is generated. Generating a second matching signal representing matching with a previous field; and generating a difference between the first matching signal and the second matching signal to obtain the rear field signal and the previous field signal. Generating a first interpolating signal, and generating a field interpolation signal by mixing the rear field signal and the front field signal according to the first mixing coefficient. Characteristic progressive scan conversion method. 6. A third representing a matching between the rear field signal and the front field signal by generating a difference between the rear field signal and the front field signal.
Generating a matching signal, and selecting the signal having the minimum value from the first matching signal, the second matching signal, and the third matching signal, thereby obtaining the intra-field interpolation signal and the field Generating a second mixing coefficient with the interpolated interpolation signal, and mixing the intrafield interpolation signal and the field interpolation signal according to the second mixing coefficient to generate an interpolation signal 6. The progressive scan conversion method according to claim 5, further comprising: