JP2001218169A - Scanning conversion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oblique lines from looking unnatural when a moving picture is displayed by a video signal (e.g. the video signal for progressive scanning) after a scanning conversion processing. SOLUTION: An interpolation point video signal is obtained by combining an inter-field interpolation processing video signal with an intra-field interpolation processing video signal in accordance with the movement of an image and a video signal Vi for interlace scanning is converted into the video signal Vp for progressive scanning by a double speed conversion processing in a scanning conversion circuit. The circuit is provided with a directional detecting part 50 for detecting a direction with the strongest correlation from the three directions comprising vertical directions and an oblique direction with the interpolation point of an interpolative scanning line as a center based on the video signals of scanning lines being adjacent to the upper and lower sides of the interpolative scanning line and with an average value calculating part 56 for calculating the average value of the video signals at two sample points which are positioned in a corresponding direction among the three sample points of the upper and lower scanning lines based on the directional detecting signal and adopting it as the intra-field interpolation processing video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to scanning by interpolating video signals of interpolation scanning lines from input video signals (for example, video signals for interlaced scanning) of scanning lines adjacent above and below the interpolation scanning lines. The present invention relates to a scan conversion circuit that outputs a video signal whose line is doubled (for example, a video signal for progressive scanning). For example, in a digital video signal processing in a display device using a PDP (plasma display panel) or an LCD (liquid crystal display) panel as a display panel, when a video signal for interlaced scanning is converted into a video signal for progressive scanning, Used.

[0002]

2. Description of the Related Art Conventionally, this type of scan conversion circuit has a 262H delay unit 12, a 1H delay unit 14,
The 62H delay unit 16, adders 18, 20, coefficient unit 22, variable coefficient units 24, 26, motion detection unit 28, and double speed conversion unit 36 were included.

[0003] The motion detecting section 28 receives a video signal Vi (for example, NTSC) for interlaced scanning input to the input terminal 10.
Video signal Vi), and the video signal Vi is supplied to the 262H delay unit 12, the 1H delay unit 14, and the 262H delay unit 16 for 52
The motion of the image is detected based on the signal delayed by 5H (1H represents one line, and the delay of 525H is equivalent to the delay of one frame). Specifically, a motion detection signal (1-K) and K are output, where K = 0 for a moving image and K = 1 for a still image.

The adder 18 adds the output signals of the 262H delay unit 12 and the 1H delay unit 14, and the coefficient unit 22 adds
Is multiplied by a factor of 1/2. As a result, the coefficient unit 22 creates a video signal (video signal of the field interpolation process) by averaging the video signals of the vertically adjacent scanning lines. One coefficient unit 24 multiplies the video signal delayed by one field in the 262H delay unit 16 (the image signal of the field interpolation process) by the detection signal K of the motion detection unit 28, and outputs the result. Multiplies the output signal of the coefficient unit 22 by the detection signal (1-K) of the motion detection unit 28 and outputs the result. The adder 20 adds the output signal of the coefficient unit 24 and the output signal of the coefficient unit 26 and outputs the result as a video signal of the interpolation scanning line.

[0005] For this reason, in the case of a moving image, K = 0, so that the coefficients of the coefficient units 24 and 26 become 0 and 1, and a video signal obtained by averaging the video signals of the vertically adjacent scanning lines (field interpolation processing). Only the video signal) is output from the adder 20, and K = 1 when the image is a still image.
The coefficient of 26 is 1, 0, which is the opposite, and only the video signal one field before (the video signal of the interpolating process between fields) is added to the adder 2.
Output from 0. For example, in the case of a moving image, the video signal at the interpolation point Np of the interpolation scanning line is, as shown by the solid line in FIG. 6, sample points Sp and Sp located vertically above and below the current field (n). In the case of a still image, the signal is a video signal of the corresponding sample point Sp in the field (n-1) one field before as shown by a dotted line in FIG.

The double speed converter 36 converts the video signal Vi into 262
The signal delayed by 263H by the H delay unit 12 and the 1H delay unit 14 and the output signal of the adder 20 are output after being subjected to double-speed conversion processing for reading out with a clock twice as fast as writing to the memory. The terminal 38 outputs a video signal Vp for progressive scanning. The double-speed conversion unit 36 includes, but is not limited to, a first memory (for example, a line memory) capable of storing the video signal output from the 1H delay unit 14, and an image of the interpolation scanning line output from the adder 20. A second memory (for example, a line memory) capable of storing signals, and alternately reading out each line with a clock twice as fast as writing to the first and second memories,
From the output terminal 38, the video signal Vp for progressive scanning
Is output.

[0007]

However, the conventional example shown in FIG. 5 has a problem that oblique lines in a moving image look unnatural. For example, when a diagonal line 40 having a line width of 2 dots is displayed in a moving image as shown in FIG.
Two interpolation points Np included in the oblique line 40 of the interpolation scanning line
1, Np2 are sample points Spb, Spc of the upper scanning line.
And a signal obtained by averaging the video signals of the sample points Spe and Spf of the lower scanning line, so that the lighting state (white) is desirable, but the half-lighting state (gray between white and black) is obtained.
Similarly, the two interpolation points Np3 and Np4 on the both sides are desirably in a non-lighting state (black) but in a half-lighting state, and have a problem that they look unnatural.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and when a moving image is displayed using a video signal after a scan conversion process (eg, a video signal for progressive scanning), vertical lines and oblique lines in the moving image are displayed. An object of the present invention is to provide a scan conversion circuit capable of preventing a line from looking unnatural and reproducing a high-quality image.

[0009]

According to a first aspect of the present invention, a scanning line is doubled by interpolating an interpolated scanning line video signal from an input video signal of a scanning line adjacent above and below the interpolated scanning line. A scan conversion circuit that outputs a video signal including the vertical direction and the oblique direction centered on the interpolation point of the interpolation scanning line based on the input video signals of a plurality of sample points of the upper scanning line and the lower scanning line. A direction detection unit that detects a direction having the highest correlation from a plurality of directions, and two samples corresponding to the detection direction of the direction detection unit among a plurality of sample points of an upper scanning line and a lower scanning line. An average value calculating unit that calculates an average value of the video signals at the points and uses the average value as the video signal of the interpolation scanning line. In such a configuration, when the direction detection unit determines that the correlation in the oblique direction is the strongest,
The average value calculation unit calculates the average value of the video signals of two sample points corresponding to the oblique direction among the plurality of sample points of the upper scanning line and the lower scanning line, and processes the average as the video signal of the interpolation scanning line. Therefore, an optimal interpolation process can be performed on the oblique lines in the moving image. When the directionality detection unit determines that the vertical correlation is the strongest, the average value calculation unit determines two of the sample points of the upper scanning line and the lower scanning line corresponding to the vertical direction. Since the average value of the video signal at the sample point is calculated and processed as the video signal of the interpolated scanning line, the optimal interpolation processing can be performed on the vertical line in the moving image.

According to a second aspect of the present invention, a motion of an image is detected based on an input video signal for interlaced scanning, and a video signal of an inter-field interpolation process and a field interpolation process are detected in accordance with the motion detection signal. In the scan conversion circuit that outputs a progressive scan video signal by double-speed conversion processing of the interpolated point video signal and the input video signal by combining the video signals of Detects the strongest correlated direction from multiple directions including the vertical and oblique directions centered on the interpolation point of the interpolated scanning line based on the input video signals of a plurality of sample points of the scanning line adjacent to the side And calculating an average value of video signals of two sample points corresponding to the detection direction of the directionality detection unit among a plurality of sample points of the upper scanning line and the lower scanning line. Inside Characterized by comprising comprises an average value calculating section for a video signal processing. In such a configuration, when the directionality detection unit determines that the correlation in the oblique direction (or the vertical direction) is the strongest, the oblique line (or the vertical line) in the moving image is processed in the same manner as the invention of claim 1. , An optimal field interpolation process can be performed.

The invention of claim 3 (or 4) is based on claim 1
In the invention of (2), in order to be able to perform appropriate interpolation processing on left and right diagonal lines centered on a vertical line in a moving image, the directionality detection unit interpolates interpolation scanning lines. It is configured to detect the direction having the strongest correlation from (2n + 1) directions (n is an integer of 1 or more) including the vertical direction centered on the point and the left and right diagonal directions.

The invention of claim 5 (or 6) is based on claim 3
In the invention according to (or 4), in order to simplify the configuration of the average value calculation unit, the average value calculation unit determines the (2n + 1) sample points of the upper scanning line based on the direction detection signal of the directionality detection unit. A first selection unit for selecting the video signal of the corresponding one of the sample points, and a corresponding one of the (2n + 1) sample points on the lower scanning line based on the direction detection signal of the direction detection unit. A second selector for selecting the video signal of one sample point, an adder for adding the signals selected by the first and second selectors, and a coefficient 1 /
And a coefficient unit for multiplying by 2 to obtain a video signal of an interpolation scanning line (or a video signal of a field interpolation process).

[0013] The invention of claim 7 (or 8) is based on claim 3
In the invention according to (or 4), in order to simplify the configuration of the average value calculation unit, the average value calculation unit is configured to set the average value calculation unit to the interpolation scan line of (2n + 1) sample points of the upper scan line and the lower scan line. An adder for adding the video signals of two sample points in the (2n + 1) direction centered on the interpolation point, and a coefficient unit for multiplying each of the (2n + 1) output signals of the adder by a coefficient １ ／ And a corresponding one of the (2n + 1) output signals of the coefficient unit based on the direction detection signal of the directionality detection unit, and outputs the image signal of the interpolation scanning line (or the image of the field interpolation processing). Signal).

According to a ninth aspect of the present invention, there is provided the third aspect of the present invention.
In the inventions of 6, 7, or 8, n = 1 is set to simplify the circuit configuration (particularly, the configuration of the direction detection unit). For example, the direction with the strongest correlation detected by the direction detection unit is
3 in vertical direction, 45 ° left diagonal direction and 45 ° right diagonal direction
Direction.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a scan conversion circuit according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment of the present invention, and the same parts as those in FIG. For convenience of explanation, input terminal 1
0, the video signal Vi for interlaced scanning input to NT
The case of a video signal of the SC system will be described. In FIG. 1, 42, 44, 46, and 48 are D delay units, 50 is a direction detection unit, 52 is a first selection unit, 54 is a second selection unit, and the first and second selection units 52, 54, The adder 18 and the coefficient unit 22 constitute an average value calculation unit 56.

The D delay units 42 and 44 are composed of, for example, D-type flip-flop circuits, and sequentially delay the output signal of the 1H delay unit 14 by one dot and output it. The D delay units 46 and 48 are constituted by, for example, D-type flip-flop circuits, and sequentially delay the output signal of the 262H delay unit 12 by one dot and output it.

The direction detecting unit 50 outputs the output signals C, B, and A of the 1H delay unit 14 and the D delay units 42 and 44, respectively.
Based on the output signals F, E, D of the 262H delay unit 12 and the D delay units 46, 48, interpolation of the interpolation scanning line is performed for sample points on the scanning lines adjacent to the upper and lower sides of the interpolation scanning line. The direction having the strongest correlation among the three directions of the vertical direction centering on the point, the 45 ° right diagonal direction, and the 45 ° left diagonal direction is detected.

The first selecting section 52, based on the direction detection signal of the direction detecting section 50, includes a 1H delay unit 14 and a D delay unit 42 corresponding to three sample points (pixel points) of the upper scanning line. , 44, a video signal of a corresponding one sample point is selected. The second selector 54
Is based on a direction detection signal of the direction detection unit 50,
From among the output signals of the 262H delay unit 12 and the D delay units 46 and 48 corresponding to the three sample points of the lower scanning line, the video signal of the corresponding one sample point is selected. The adder 18 adds the output signal of the first selection unit 52 and the output signal of the second selection unit 54, and the coefficient unit 22 multiplies the output signal of the adder 18 by a coefficient 、 to perform a field interpolation process. As a video signal.

Next, the operation of FIG. 1 will be described with reference to FIGS. 2 and 3. (1) The NTSC video signal Vi input to the input terminal 10 is a 262H delay unit 12, a 1H delay unit 14, 262
The signal is delayed by (1 frame + 1 dot) by the H delay unit 16 and the D delay unit 35, and is input to the coefficient unit 24 as a video signal for inter-field interpolation. For example, as shown by an arrow in FIG. 2B, the interpolation point Np of the interpolation scanning line of the field (n) is used.
For the field (n-
The video signal of the sample point Sp at a predetermined position on the corresponding scanning line in 1) is input to the coefficient unit 24 as a video signal of the field interpolation processing.

(2) A signal C obtained by delaying the input video signal Vi by 263H by the 262H delay unit 12 and the 1H delay unit 14.
And the signal B delayed by one dot by the D delay unit 42
And the signal A delayed by one dot by the D delay unit 44
262H by the 262H delay unit 12
When the signal F delayed by one minute, the signal E further delayed by one dot by the D delay unit 46, and the signal D further delayed by one dot by the D delay unit 48 are input to the direction detection unit 50, The direction detection unit 50 calculates the interpolation point Np of the interpolation scanning line.
Vertical centered on the center, 45 ° diagonally left and 4 diagonally right
In three directions of 5 °, corresponding sample points Spb, Spa, Spc and Spe of the upper scanning line and the lower scanning line,
The luminance level difference between Spf and Spd is obtained and compared, and the smallest value (that is, the direction with the strongest correlation) is detected.

(3) When the direction detection signal of the direction detection section 50 is input to the first selection section 52, the first selection section 52
Based on the direction detection signal, a corresponding signal (for example, signal C) among the input signals C, B, and A is selected and output. For example, the direction detection signal of the direction detection unit 50 is 45 ° diagonally right.
2A, the interpolation point Np among the three sample points Spa, Spb, and Spc of the upper scanning line in FIG.
Sample point Spc located at an angle of 45 °
Is selected. Further, if the direction detection signal is in the vertical direction or the 45 ° left diagonal direction, similarly,
The video signal B at the sample point Spb or the video signal A at the sample point Spa in FIG. 2A is selected and output.

(4) When the direction detection signal of the direction detection section 50 is input to the second selection section 54, the second selection section 54
Based on the direction detection signal, a corresponding signal (for example, signal D) among the input signals F, E, and D is selected and output. For example, the direction detection signal of the direction detection unit 50 is 45 ° diagonally right.
2A, the interpolation point Np among the three sample points Spd, Spe, Spf of the lower scanning line in FIG.
Sample point Spd located at an angle of 45 ° to the right with respect to
And outputs the selected video signal D. Further, assuming that the direction detection signal is in the vertical direction or the 45 ° left diagonal direction, similarly, the video signal E of the sample point Spe or the video signal F of the sample point Spf in FIG. .

(5) The adder 18 adds the output signal of the first selector 52 and the output signal of the second selector 54, and
Multiplies the output signal of the adder 18 by a coefficient １ ／ and outputs the resulting signal to the coefficient unit 26 as a video signal for field interpolation processing.
For example, if the direction detection signal of the direction detection unit 50 is
2A, the video signal C at the sampling point Spc of the upper scanning line and the sampling point S of the lower scanning line in FIG.
A video signal obtained by adding the pd video signal D, halving the average, and outputting the resulting signal is output to the coefficient unit 26 as a video signal for field interpolation processing. If the direction detection signal is in the vertical direction, the sample point Spb of the upper scanning line in FIG.
The video signal B is added to the video signal E of the sample point Spe of the lower scanning line, and the video signal is averaged by １ ／ and output to the coefficient unit 26 as the video signal of the field interpolation processing.

(6) The input video signal Vi and the input video signal Vi are transmitted to the 262H delay unit 12, the 1H delay units 14 and 2
When the signal delayed by one frame by the 62H delay unit 16 is input to the motion detecting unit 28, the motion detecting unit 28 compares the corresponding video signals between frames to detect the motion of the image. K = 0, K = 1 for a still image
Then, a motion detection signal (1-K), K, is output.

(7) In the case of a moving image, the motion detection signal (1-K) of the motion detector 28, K is 1, 0 (when K = 0)
Therefore, only the video signal of the field interpolation processing output from the coefficient unit 22 passes through the coefficient unit 26 and is input to the double-speed conversion unit 36 via the adder 20. For this reason, the double-speed conversion unit 36 delays the video signal Vi by (263H + 1D) by the 262H delay unit 12, the 1H delay unit 14, and the D delay unit 34, and performs the field interpolation processing output from the adder 20. A double speed conversion process with the video signal is performed, and the output terminal 38
Outputs a video signal Vp for progressive scanning.

(8) Accordingly, when the oblique line 40 having a line width of 2 dots and a diagonally right direction of 45 ° as shown in FIG. 3 appears in the moving image, the direction detection unit 50 sets the diagonally right direction of 45 °. The direction is detected as the direction having the strongest correlation, and the first and second selecting units 52 and 54 use this detection signal to determine the interpolation point N of the interpolation scanning line.
The video signals C and D of the sample points Spc and Spd in the lighting state of the upper scanning line and the lower scanning line which are positioned at an angle of 45 ° to the right with respect to p1 are selected, and averaged by the adder 18 and the coefficient unit 22. It is assumed that the video signal is at the interpolation point Np1. Similarly,
The video signal of the interpolation point Np2 is also a signal obtained by averaging the video signal of the lighting sample point. Therefore, the interpolation point Np
1, Np2 is in a desirable lighting state, and the interpolation points Np3, Np4 on both sides are in a desirable non-lighting state, so that the oblique line 40 can be prevented from looking unnatural.

(9) For a still image, the motion detection unit 28
Of the motion detection signal (1-K), K is 0, 1 (when K = 1), so that the video signal of the field interpolation processing output from the D delay unit 35 (that is, the video signal one field before) Only the signal passes through the coefficient unit 24 and is input to the double speed conversion unit 36 via the adder 20. For this reason, the double speed conversion unit 36
A double-speed conversion process of a signal obtained by delaying the video signal Vi by (263H + 1D) by the 262H delay unit 12, the 1H delay unit 14, and the D delay unit 34 and a video signal of the field interpolation process output from the D delay unit 35 is performed. Then, a video signal Vp for progressive scanning is output to the output terminal 38.

In the embodiment shown in FIG. 1, the case where the average value calculating section is constituted by the first and second selecting sections, the adder and the coefficient unit has been described. However, the present invention is not limited to this.
As shown in the figure, the average value calculation unit 56a is
0, 62, 64 and three coefficient units 66, 68, 70,
It can also be used in the case where it is configured with the selection unit 72.

In FIG. 4, an adder 60 adds the signal A and the signal F, and a coefficient unit 66 multiplies the output signal of the adder 60 by a coefficient 出力 and outputs the result. For this reason, from the output side of the coefficient unit 66, the sample point Spa of the upper scanning line and the lower scanning line which are located at an angle of 45 ° to the left with respect to the interpolation point Np of the interpolation scanning line of FIG. A video signal obtained by averaging the video signals A and F at the sample point Spf is output. Further, the addition unit 62
Adds the signal B and the signal E, and the coefficient unit 68 multiplies the output signal of the adder 62 by a coefficient １ ／ and outputs the result. For this reason, from the output side of the coefficient unit 68, the sample point Spb of the upper scan line and the sample point Spe of the lower scan line located in the vertical direction with respect to the interpolation point Np of the interpolation scan line in FIG. A video signal obtained by averaging the video signals B and E is output. The adder 64 adds the signal C and the signal D, and the coefficient unit 70 multiplies the output signal of the adder 64 by a coefficient 係数 and outputs the result. For this reason, from the output side of the coefficient unit 70, the sample point Spc of the upper scanning line and the lower scanning line which are located at an angle of 45 ° diagonally to the right with respect to the interpolation point Np of the interpolation scanning line of FIG. A video signal obtained by averaging the video signal C and the video signal D at the sample point Spd is output.

When the direction detection signal of the direction detection unit 50 is input to the selection unit 72, the selection unit 72 outputs one of the output signals of the three coefficient units 66, 68, 70 based on the direction detection signal. Select and output as a video signal for field interpolation. For example, the output signal of the coefficient unit 66 is selected when the direction detection signal of the direction detection unit 50 is in the 45 ° left diagonal direction, and when the direction detection signal is in the vertical direction, the coefficient unit 6 is selected.
8 is selected, and the output signal of the coefficient unit 70 is selected when the direction detection signal is in the 45 ° right diagonal direction.

In the case of a moving image, the motion detection signal (1-K) of the motion detection section 28, K becomes 1, 0 (when K = 0). Only the signal passes through the coefficient unit 26 and is input to the double speed conversion unit 36 via the adder 20. For this reason, the double speed conversion unit 36
The video signal Vi is delayed by the amount of (263H + 1D) and the video signal of the field interpolation process output from the adder 20 is subjected to double speed conversion processing, and a video signal Vp for progressive scanning is output to the output terminal 38. . Therefore, when a line width of 2 dots as shown in FIG. 3 and an oblique line 40 in the right oblique direction at 45 ° appear in the moving image, the oblique line 40 looks unnatural as in the case of FIG. Can be prevented.

In the embodiment shown in FIGS. 1 and 4, in order to simplify the circuit configuration (especially the configuration of the direction detection unit), the direction detection unit performs upward scanning with respect to the interpolation point of the interpolation scanning line. Vertical direction of line and lower scanning line, 45 ° left diagonal direction and 4 right diagonal direction
Although the case where the direction having the strongest correlation in the three directions of 5 ° is detected has been described, the present invention is not limited to this, and the upper scanning line and the lower scanning line are set with respect to the interpolation points of the interpolation scanning line. It can be used in the case of detecting the (2n + 1) direction including the vertical direction, the diagonal direction, or the direction having the strongest correlation in the 2n direction. For example, it is also possible to use the case where n in the (2n + 1) direction is set to 2. In other words, the direction detection unit detects the vertical direction, the 45 ° left diagonal direction, the 45 ° right diagonal direction, and the 3 left diagonal direction.
The present invention can also be applied to a case in which the direction having the strongest correlation among the five directions of the 0 ° direction and the 30 ° right diagonal direction is detected. In this case, it is possible to prevent more oblique lines in the moving image from looking unnatural without making the configuration of the directionality detection unit so complicated.

In the embodiment shown in FIGS. 1 and 4, in order to simplify the structure of the average value calculating section, the average value calculating section
The case where the second selector, the adder and the coefficient unit are configured, or the case where the second selector is configured with the (2n + 1) adder, the coefficient unit and the selector are described. However, the present invention is not limited to this. Lines and (2n + 1) or 2n lower scan lines
The average value of the video signals of two sample points corresponding to the detection direction of the directionality detection unit out of the sample points may be calculated and used as the video signal for the field interpolation processing.

In the embodiment shown in FIGS. 1 and 4, the motion detection signal (1-K) and K of the motion detection unit 28 are 0 and 1 for a still image, and the motion detection signal of the motion detection unit 28 for a moving image. (1-K), the case where K is 1, 0 has been described, but the present invention is not limited to this, and the motion detection unit 2
Eight motion detection signals (1−K) can also be used in cases where K of K is other than 2 types of 1 and 0 (for example, in the case of 3 types of K, 1 1/2 and 0). For example, when the image is completely still, the motion detection signal (1-K) of the motion detection unit 28, K is 0, 1 (when K = 1),
When the image is slightly moving, the motion detection signal (1-K) of the motion detecting unit 28 is 、, （(when K = １ ／). The motion detection signal (1-K) of the detection unit 28, where K is 1, 0 (K
= 0) can also be used.

In the above embodiment, the input video signal is NT
Although the case of the video signal of the SC system has been described, the present invention is not limited to this, and the present invention can also be used for the video signal of the PAL system, the SECAM system, and the HDTV system. For example, if the input video signal is PAL or S
In the case of an ECAM video signal, 26 in FIGS.
By replacing the 2H delay units 12 and 16 with a 312H delay unit, when the input video signal is an HDTV video signal, the 262H delay units 12 and 16 in FIGS.
It can be used by replacing it with a 2H delay unit.

In the above embodiment, the motion of an image is detected based on the input video signal for interlaced scanning, and the video signal for the field interpolation processing and the video signal for the field interpolation processing are detected in accordance with the motion detection signal. The case where the present invention is applied to a scan conversion circuit that outputs a video signal for progressive scanning in the double-speed conversion processing of the interpolation point video signal and the input video signal by obtaining the interpolation point video signal by combining the video signals has been described. However, the present invention is not limited to this. A video signal obtained by interpolating a video signal of an interpolation scanning line from an input video signal of a scanning line adjacent above and below the interpolation scanning line and doubling the scanning line is obtained. The present invention can be used for an output scan conversion circuit. For example, in FIG.
6, motion detector 28, coefficient units 24 and 26, D delay unit 3
0, 32, 35 and the adder 20 are omitted, and the input interlaced scanning video signal Vi is converted into a 1H delay unit 14 and a D
The signal delayed by the delay unit 34 and the video signal of the interpolated scanning line obtained by the average value calculation unit 56 are input to the double speed conversion unit 36, and the output terminal 38 is output by the double speed conversion processing of the double speed conversion unit 36.
Can also be used in a case where the video signal Vp for progressive scanning is output to the CPU.

[0037]

According to a first aspect of the present invention, there is provided a scan conversion circuit for interpolating a video signal of an interpolated scan line from an input video signal of an upper scan line and a lower scan line to output a video signal whose scanning line is doubled. A directional detection unit that detects a direction having the strongest correlation from a plurality of directions including a vertical direction and an oblique direction centered on an interpolation point of an interpolation scanning line, and a plurality of upper scanning lines and lower scanning lines. The average value of the video signals of the two sample points corresponding to the detection direction of the directionality detection unit among the sample points is calculated and used as the video signal of the interpolation scanning line. When a moving image is displayed with the video signal after the conversion processing, it is possible to prevent a vertical line and an oblique line in the moving image from appearing unnatural and to reproduce a high-quality image. For example, if the directionality detection unit determines that the correlation in the oblique direction is the strongest, the average value calculation unit determines that the correlation is located in the corresponding oblique direction among the plurality of sample points of the upper scan line and the lower scan line. Since the average value of the video signals of the sample points is calculated and processed as the video signal of the interpolated scanning line, it is possible to perform the optimal interpolation processing on the diagonal line in the moving image,
The oblique line can be prevented from looking unnatural.

According to a second aspect of the present invention, a motion of an image is detected based on an input video signal for interlaced scanning, and a video signal of an inter-field interpolation process and a field interpolation process are detected in accordance with the motion detection signal. An interpolation point video signal is obtained by combining the video signals of the above, and a scanning conversion circuit that outputs a video signal for progressive scanning by a double-speed conversion process of the interpolation point video signal and the input video signal, the interpolation point of the interpolation scanning line A direction detection unit that detects a direction having the strongest correlation from a plurality of directions including a vertical direction and an oblique direction centered on a direction, and a direction detection among a plurality of sample points of an upper scanning line and a lower scanning line. The average value of the video signals of the two sample points corresponding to the detection direction of the field, and the average value calculation unit as the video signal of the field interpolation processing.
When displaying a moving image with a video signal after the progressive conversion processing, similar to the first aspect of the present invention, it is possible to prevent a vertical line and an oblique line in the moving image from appearing unnatural and reproduce a high-quality image. Can be.

The invention of claim 3 (or 4) is based on claim 1
(2) In the invention of (2), the directionality detection unit correlates from (2n + 1) directions (n is an integer of 1 or more) including a vertical direction centered on the interpolation point of the interpolation scanning line and a left and right diagonal direction. Since it is configured to detect the direction with the strongest gender, it is possible to perform appropriate interpolation processing on left and right diagonal lines centered on a vertical line in a moving image.

The invention according to claim 5 (or 6) is based on claim 3
In the invention according to (or 4), the average value calculation unit determines the average value of the upper scanning line based on the direction detection signal of the directionality detection unit.
1) a first selection unit that selects a video signal of a corresponding one of the sample points; and (2n + 1) samples of a lower scanning line based on a direction detection signal of a direction detection unit. A second selection unit for selecting a video signal of one corresponding sample point from the points, an addition unit for adding the signals selected by the first and second selection units, and a coefficient added to an output signal of the addition unit Since it is composed of a coefficient unit that is multiplied by と す る to generate a video signal of the interpolation scanning line (or a video signal of the field interpolation processing), the configuration of the average value calculation unit can be simplified.

According to the invention of claim 7 (or 8), claim 3
(4) In the invention of (4), the average value calculation unit is configured to determine each of the (2n + 1) sample points of the upper scanning line and the lower scanning line in each of the (2n + 1) directions around the interpolation point of the interpolation scanning line. An adder for adding the video signals of the two sample points;
A coefficient unit for multiplying each of the (2n + 1) output signals of the adding unit by a coefficient 、 and a corresponding one of the (2n + 1) output signals of the coefficient unit based on the direction detection signal of the direction detection unit. Since one output signal is composed of the selection unit that sets the video signal of the interpolation scanning line (the video signal of the field interpolation processing), the configuration of the average value calculation unit can be simplified.

The ninth aspect of the present invention is the third aspect of the present invention.
Since n = 1 in the invention of 6, 7, or 8, the circuit configuration (particularly, the configuration of the direction detection unit) can be simplified. For example, the direction having the strongest correlation detected by the direction detection unit is defined as a vertical direction, a 45 °
The circuit configuration (particularly, the configuration of the direction detection unit) can be simplified by using three directions (an example in the case of n = 1).

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a scan conversion circuit according to the present invention.

FIGS. 2A and 2B are diagrams for explaining the operation of FIG. 1, wherein FIG. 2A is an explanatory diagram of a field interpolation process, and FIG. 2B is an explanatory diagram of an inter-field interpolation process.

FIG. 3 is a diagram for explaining the operation of FIG. 1 and is an explanatory diagram of a field interpolation process for a diagonal line in a moving image.

FIG. 4 is a block diagram showing another embodiment of the scan conversion circuit according to the present invention.

FIG. 5 is a block diagram showing a conventional example.

FIG. 6 is a diagram for explaining the operation of FIG. 5 and is an explanatory diagram of a field interpolation process and an inter-field interpolation process.

FIG. 7 is a diagram for explaining the operation of FIG. 5 and is an explanatory diagram of a field interpolation process for oblique lines in a moving image.

[Explanation of symbols]

10 ... input terminal, 12, 16 ... 262H delay device, 1
4 1H delay unit 18, 20, 60, 62, 64 Adder 22, 66, 68, 70 Coefficient unit 24, 26
... coefficient unit with variable coefficient 28 motion detector 3
0, 32, 34, 35, 42, 44, 46, 48... D delay unit, 36... Double speed conversion unit, 38.
... diagonal line, 50 ... direction detection unit, 52 ... first selection unit, 54 ... second selection unit, 56, 56a ... average value calculation unit, 72 ... selection unit, A, B, C ... upper scanning line sample Video signals at points Spa to Spc, D, E, F... Video signals at sample points Spd to Spf of lower scanning line, N
p, Np1 to Np4 ... interpolation points, Sp, Spa to Spf ...
Sample points, K, 1-K: a pair of motion detection signals output from the motion detector 28; Vi: a video signal for interlaced scanning; Vp: a video signal for progressive scanning.

Continued on the front page (72) Inventor Makoto Ikeda 1116 Suenaga, Takatsu-ku, Kawasaki-shi, Kanagawa F-term in Fujitsu General Limited (reference) 5C063 AA06 AC01 BA04 BA09 BA10 BA12 CA01 CA05 CA07

Claims (9)

[Claims] 1. A scanning conversion circuit for interpolating a video signal of an interpolated scanning line from an input video signal of a scanning line adjacent to an upper side and a lower side of an interpolated scanning line and outputting a video signal of a doubled scanning line, Based on input video signals of a plurality of sample points of the upper scanning line and the lower scanning line, the correlation of the correlation among the plurality of directions including a vertical direction and an oblique direction centered on the interpolation point of the interpolation scanning line. A direction detection unit for detecting a strong direction, and an average value of video signals of two sample points corresponding to the detection direction of the direction detection unit among a plurality of sample points of the upper scanning line and the lower scanning line. And a mean value calculating unit for calculating a video signal of an interpolation scanning line. 2. The method according to claim 1, wherein a motion of the image is detected on the basis of the input video signal for interlaced scanning, and a video signal for inter-field interpolation and a video signal for field interpolation are combined in accordance with the motion detection signal. To obtain the interpolation point video signal,
In a scan conversion circuit that outputs a progressive scan video signal by a double-speed conversion process between the interpolation point video signal and the input video signal, the input video at a plurality of sample points of a scan line adjacent to the upper and lower sides of the interpolation scan line Based on the signal, a directionality detection unit that detects a direction having the strongest correlation among a plurality of directions including a vertical direction and an oblique direction centered on the interpolation point of the interpolation scanning line, and the upper scanning line and the lower direction detecting unit. Calculating an average value of video signals of two sample points corresponding to the detection direction of the directionality detection unit among a plurality of sample points of a side scanning line, and calculating an average value as a video signal of a field interpolation process And a scan conversion circuit. 3. The direction detection unit includes a vertical direction centered on an interpolation point of an interpolation scanning line and a left and right diagonal direction (2n +
2. The scan conversion circuit according to claim 1, wherein a direction having the strongest correlation is detected from 1) directions (n is an integer of 1 or more). 4. The direction detection unit includes a vertical direction centered on an interpolation point of an interpolation scanning line and a left and right diagonal direction (2n +
3. The scan conversion circuit according to claim 2, wherein a direction having the highest correlation is detected from 1) directions (n is an integer of 1 or more). 5. An average value calculating section for selecting a video signal of a corresponding one of (2n + 1) sample points on an upper scanning line based on a direction detection signal of a direction detecting section. A first selection unit, and a second selection unit that selects a video signal of a corresponding one sample point from (2n + 1) sample points on the lower scanning line based on a direction detection signal of the direction detection unit. An addition unit for adding the signals selected by the first and second selection units, and a coefficient １ ／ added to an output signal of the addition unit.
4. The scan conversion circuit according to claim 3, further comprising: a coefficient unit that multiplies the image signal by an interpolation scan line. 6. An average value calculating section for selecting a video signal of a corresponding one of (2n + 1) sample points on an upper scanning line based on a direction detection signal of a direction detecting section. A first selection unit, and a second selection unit that selects a video signal of a corresponding one sample point from (2n + 1) sample points on the lower scanning line based on a direction detection signal of the direction detection unit. An addition unit for adding the signals selected by the first and second selection units, and a coefficient １ ／ added to an output signal of the addition unit.
5. The scan conversion circuit according to claim 4, further comprising: a coefficient unit which multiplies the image signal by a multiplication by a factor to obtain a video signal for the field interpolation processing. 7. An average value calculating section, of the (2n + 1) sample points of the upper scanning line and the lower scanning line, two each in the (2n + 1) direction centering on the interpolation point of the interpolation scanning line. An adder for adding the video signals at the sample points, and (2)
a coefficient unit that multiplies each of the (n + 1) output signals by a coefficient と, and a corresponding one of the (2n + 1) output signals of the coefficient unit based on the direction detection signal of the directionality detection unit.
4. The scan conversion circuit according to claim 3, further comprising: a selection unit that uses the output signals as a video signal of an interpolation scanning line. 8. An average value calculating section, of the (2n + 1) sample points of the upper scanning line and the lower scanning line, each of two sample points in the (2n + 1) direction centered on the interpolation point of the interpolation scanning line. An adder for adding the video signals at the sample points, and (2)
a coefficient unit that multiplies each of the (n + 1) output signals by a coefficient と, and a corresponding one of the (2n + 1) output signals of the coefficient unit based on the direction detection signal of the directionality detection unit.
5. The scanning conversion circuit according to claim 4, further comprising a selection unit that uses the output signals as video signals for field interpolation processing. 9. The method according to claim 3, wherein n = 1.
The scan conversion circuit according to 7 or 8.