JPH11196382A - In-field interpolation method and circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a contour part from being blurred and to prevent a smooth change part form being inconspicuous in raggedness by applying interpolation to a contour part of an image without losing the contour and applying interpolation to a smooth changing part of the image in a smoothly changing way. SOLUTION: The interpolation circuit is used to convert a received video signal Vi for interlace scanning into a video signal Vp for progressing scanning. The interpolation circuit is provided with 1-line delay section 12 that delays the signal Vi by one line, a contour amount detection section 30 that detects a contour amount R of the signal Vi based on the 1-line delay signal and the signal Vi, a compactor section 32 that compares the detected contour amount R with a setting value S, and an interpolation point arithmetic section 34 that replaces the signal Vi of the scanning line adjacent to an upper part of an interpolation scanning line with a signal averaging he signals Vi of the scanning lines adjacent to the upper and lower sides of the interpolation scanning line so as to output the result as the video signal of the interpolation scanning line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting an input video signal (for example, an interlace scanning video signal) into a video signal whose scanning line is doubled (for example, a progressive scanning video signal). Field interpolation method and circuit used in the method. For example, PDP
In a digital video signal processing in a display device using a (plasma display panel) or an LCD (liquid crystal display) panel as a display panel, when the video signal for interlaced scanning is converted into the video signal for progressive scanning, the same field is used. The present invention relates to a field interpolation method and circuit for obtaining a video signal of an interpolated scanning line (a scanning line connecting interpolation points) by scanning line interpolation.

[0002]

2. Description of the Related Art Conventionally, this kind of field interpolation method has been performed by a zero-order interpolation method using a circuit shown in FIG. 4 or an average value interpolation method using a circuit shown in FIG. .
The 0-order interpolation method using the circuit shown in FIG.
The video signal Vi for interlaced scanning input into the memory is delayed by one line by the one-line delay unit 12 to generate a video signal of an interpolated scanning line, and is read out with a clock twice as fast as writing to the memory. The double-speed conversion unit 14 outputs a video signal Vp for progressive scanning from the output terminal 16. The double-speed conversion unit 14 is not limited to this. For example, a first memory (for example, a line memory) capable of storing a video signal input to the input terminal 10 and an image of an interpolation scanning line delayed by the one-line delay unit 12 A second memory (for example, a line memory) capable of storing a signal,
A video signal Vp for progressive scanning is output from the output terminal 16 by alternately reading out each line with a clock twice as fast as writing to the first and second memories. As this video signal, the video signal of the upper scanning line as shown in FIG. 6 is used as it is as the video signal of the interpolation scanning line. The average value interpolation method using the circuit shown in FIG. 5 is based on an interlaced scanning video signal Vi input to the input terminal 10 by the interpolation point calculation unit 22 including the adder 18 and the multiplier 20. The signal obtained by averaging the signal obtained by delaying the signal by one line in the one-line delay unit 12 to generate a video signal of the interpolation scanning line, and outputting the video signal Vp for progressive scanning from the output terminal 16 using the double-speed conversion unit 14 I was trying to do it. As the video signal Vp, a signal obtained by averaging the video signals of the upper and lower scanning lines as shown in FIG. 7 is used as the video signal of the interpolation scanning line.

[0003]

However, in the circuit using the zero-order interpolation method shown in FIG. 4, as shown in FIG. 6, the video signal of the adjacent upper scanning line is used as the video signal of the interpolation scanning line. Is used as it is, so that there is a problem that jaggedness is noticeable in a portion where the image changes smoothly. Further, in the circuit using the average value interpolation method shown in FIG. 5, as shown in FIG. 7, the video signals of the adjacent scanning lines above and below the interpolation scanning line are averaged as the video signals of the interpolation scanning line. Since the converted signal is used, there has been a problem that the outline portion of the image becomes smooth and the outline is lost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and performs interpolation in which jaggies are not conspicuous in a portion where an image changes smoothly and contours are not lost in a contour portion of the image. It is an object of the present invention to provide a field interpolation method and circuit which can perform the field interpolation.

[0005]

According to the first and second aspects of the present invention,
In a field interpolation method used when converting an input video signal (for example, an interlace scanning video signal) to a video signal whose scanning line is doubled (for example, a progressive scanning video signal), interpolation is performed. The contour amount is detected from the input video signals of the scanning lines adjacent to the upper and lower sides of the scanning line, and when the contour amount is larger than the set value, the input video signal of the scanning line adjacent to the upper or lower side of the interpolation scanning line is interpolated. When the contour amount is smaller than the set value, a signal obtained by averaging the input video signals of the scanning lines adjacent to the upper side and the lower side of the interpolation scanning line is used as the video signal of the interpolation scanning line. I do.

According to a third aspect of the present invention, there is provided a circuit for implementing the method of the first or second aspect, wherein a one-line delay unit for delaying an input video signal by one line, and the one-line delay signal A contour amount detector for detecting a contour amount of the input video signal based on the input video signal, a comparator for comparing the detected contour amount with a set value, and an upper portion of the interpolation scanning line corresponding to the comparison output. Alternatively, an interpolation that switches between an input video signal of a scanning line adjacent to the lower side and a signal obtained by averaging the input video signals of the scanning lines adjacent to the upper side and the lower side of the interpolation scanning line, and outputs the signal as a video signal of the interpolation scanning line. And a point calculation unit.

When the contour component of the image is equal to or more than a predetermined value and the contour amount detected by the contour amount detecting section is larger than the set value, the input video signal of the scanning line adjacent to the upper or lower side of the interpolation scanning line is obtained by the comparison output of the comparing section. Is output as the video signal of the interpolation scanning line, so that interpolation without losing the contour can be performed. When the contour component of the image is equal to or less than a predetermined value and the contour amount detected by the contour amount detection unit is smaller than the set value, the comparison output of the comparison unit averages the input video signals of the scanning lines adjacent above and below the interpolation scanning line. Since the signal thus output is output as a video signal of the interpolation scanning line, it is possible to perform interpolation in which jaggedness is not noticeable in a smoothly changing portion of the image.

According to a fifth aspect of the present invention, in order to simplify the circuit configuration of the interpolation point calculating section,
An adder for adding the input video signal to the output signal of the one-line delay unit;
A multiplier for multiplying by a factor of / 2, and a switch for switching between the multiplied signal of the multiplier and the input video signal in accordance with the comparison output of the comparison unit and outputting the signal as an interpolated scanning line video signal.

According to the sixth and seventh aspects of the present invention, an input video signal (for example, a video signal for interlaced scanning) is converted into a video signal whose scanning line is doubled (for example, a video signal for progressive scanning). In the field interpolation method used in this case, the contour amount is detected from the input video signals of the scanning lines adjacent to the upper side and the lower side of the interpolation scanning line, and the upper or lower side of the interpolation scanning line is detected according to the contour amount. The mixing ratio between the input video signal of the adjacent scanning line and the signal obtained by averaging the input video signals of the scanning lines adjacent above and below the interpolation scanning line is switched, and the signal mixed at this mixing ratio is used as the interpolation scanning line. Characterized in that the video signal is

The present invention according to claims 8 and 9 is a circuit for implementing the method according to claims 6 and 7, wherein the one-line delay section for delaying the input video signal by one line, and the one-line delay signal A contour amount detector for detecting the contour amount of the input video signal based on the video signal; and a pair of a plurality of preset coefficients corresponding to the contour amount detected by the contour amount detector. A contour amount / coefficient conversion unit for outputting a coefficient, and an input video signal of a scanning line adjacent to an upper side or a lower side of the interpolation scanning line and an upper side of the interpolation scanning line according to the coefficient output from the contour amount / coefficient conversion unit And an interpolation point calculation unit for switching a mixing ratio between an input video signal of a scanning line adjacent to the lower side and a signal averaged, and outputting a signal mixed at the mixing ratio as a video signal of an interpolation scanning line. It is characterized by becoming.

According to the contour amount detected by the contour amount detecting section,
The input video signal of the scanning line adjacent to the upper or lower side of the interpolation scanning line, the mixing ratio of the signal obtained by averaging the input video signal of the scanning line adjacent to the upper and lower sides of the interpolation scanning line is switched, Since the signal mixed at this mixing ratio becomes the video signal of the interpolation scanning line, the larger the contour amount is, the more the input signal of the scanning line adjacent to the upper or lower side of the interpolation scanning line is included in the video signal of the interpolation scanning line. Signal), and the latter (a signal obtained by averaging the input video signals of the adjacent scanning lines above and below the interpolation scanning line) decreases. For this reason, it is possible to perform the interpolation without losing the contour at the contour portion of the image, and to perform the interpolation in which the jaggedness is not noticeable at the smoothly changing portion of the image.

According to a tenth aspect of the present invention, in the eighth and 95th aspects, the signal obtained by delaying the interpolation point operation unit by a one-line delay unit in order to simplify the circuit configuration of the interpolation point operation unit. Adder for adding the input signal and the input video signal, a first multiplier for multiplying the addition signal of the first adder by a factor of と, and a contour amount / coefficient for the multiplication signal of the first multiplier. A variable coefficient second multiplier for multiplying one of the coefficients output from the conversion unit, and a variable coefficient type multiplier for multiplying the signal delayed by the one-line delay unit with the other coefficient output from the contour amount / coefficient conversion unit It comprises a third multiplier and a second adder for adding the multiplied signals of the second and third multipliers and outputting as a video signal of the interpolation scanning line.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a field interpolation method and circuit according to the present invention will be described below with reference to the drawings. FIG. 1 shows a first embodiment (mainly corresponding to the inventions of claims 1 to 3), and the same parts as those in FIGS. 4 and 5 are denoted by the same reference numerals. In FIG. 1, reference numeral 10 denotes an input terminal for inputting a digital video signal Vi for interlaced scanning, and reference numeral 12 denotes a one-line delay unit for delaying the input video signal Vi by one line and outputting the delayed signal. Reference numeral 30 denotes a contour amount detection unit that detects a contour amount R of the input video signal Vi based on the input video signal Vi and the video signal output from the one-line delay unit 12, and 32 sets the detected contour amount R in advance. Set value S as threshold
This is a comparison unit for comparing with. Numeral 34 denotes an interpolation point calculating unit for calculating a video signal of an interpolated scanning line by scanning line interpolation in the same field, 14 denotes a double-speed conversion unit which reads out data with a clock twice as fast as writing to the internal memory, and 16 denotes a double-speed conversion unit An output terminal for outputting a video signal Vp for progressive scanning.

The interpolation point calculator 34 calculates the input video signal V
i, and an adder 36 that adds the video signal output from the one-line delay unit 12, and a half of the added signal of the adder 36.
And a switch 40 for switching and outputting the video signal obtained by the multiplier 38 and the video signal output from the one-line delay unit 12. The switch 40 is switched by the comparison output of the comparator 32. The double speed conversion unit 14 includes, but is not limited to, for example, a video signal V input to the input terminal 10.
i and a second memory capable of storing the video signal of the interpolation scanning line from the switch 40.
A memory (for example, a line memory), and alternately reads out each line with a clock twice as fast as writing to the first and second memories. The signal Vp is output.

Next, the operation of FIG. 1 will be described. When the outline component of the image based on the video signal Vi input to the input terminal 10 is equal to or less than a predetermined amount and the outline amount R detected by the outline amount detection unit 30 is smaller than the set value S (R <S or R ≦ S), the solid line in FIG. As shown by, the switch 40 outputs the output signal of the multiplier 38 to the double speed conversion unit 14 by the comparison output of the comparison unit 32. For this reason, as in the case of the average value interpolation method shown in FIG. 7, the signal obtained by averaging the input video signals of the scanning lines adjacent to the upper and lower sides of the interpolation scanning line is used as the video signal of the interpolation scanning line. The data is output to the double speed conversion unit 14. Therefore, it is possible to perform interpolation in which the jaggedness is not noticeable in a smoothly changing portion of the image. The contour component of the image based on the video signal Vi input to the input terminal 10 is equal to or more than a predetermined amount, and the contour amount R detected by the contour amount detection unit 30 is larger than a set value S (R ≧ S or R>
At S), the switch 40 outputs the output signal of the one-line delay unit 12 to the double speed conversion unit 14 by the comparison output of the comparison unit 32, as indicated by the dotted line in the figure. Therefore, FIG.
As in the case of the zero-order interpolation method shown in the above, the input video signal of the scanning line adjacent above the interpolation scanning line is output to the double speed conversion unit 14 as the video signal of the interpolation scanning line. Therefore, it is possible to perform interpolation without losing the outline at the outline portion of the image.

In the embodiment of FIG. 1, the interpolation point calculation unit is constituted by an adder, a multiplier and a switch. However, the present invention is not limited to this, and the interpolation is performed according to the comparison output of the comparison unit. Switching between an input video signal of a scanning line adjacent to the upper side of the scanning line and a signal obtained by averaging the input video signals of the scanning lines adjacent to the upper side and the lower side of the interpolation scanning line, and outputting as a video signal of the interpolation scanning line Should be fine.

FIG. 2 shows a second embodiment (mainly corresponding to the inventions of claims 4 to 6) of the present invention, and the same parts as those in FIG. In FIG. 2, 10 is an input terminal, 1
2 is a one-line delay unit, 14 is a double speed conversion unit, 16 is an output terminal, 30 is an outline amount detection unit, 42 is an outline amount / coefficient conversion unit,
Reference numeral 44 denotes an interpolation point calculation unit.

The contour amount / coefficient conversion unit 42 includes, for example, an LUT (lookup table) in which the level of the contour amount R and a plurality of pairs of coefficients j and 1-j are stored in correspondence with each other.
As shown in FIG. 7, depending on which of the nine levels 0 to 8 the level of the contour amount R detected by the contour amount detection unit 30 belongs to, a plurality of pairs of preset coefficients j and 1-j correspond to each other. Done 1
Output the coefficient of the pair. For example, when the level of the contour amount R is in the stage of 3, the coefficient is 5/8 (j = 5/8), 3/8
(1-j = 3/8) is output.

The interpolation point calculator 44 calculates the input video signal V
i, and a first adder 46 that adds the video signal output from the one-line delay unit 12, and multiplies the addition signal of the first adder 46 by a factor of し to generate a video signal Vi and a one-line delay signal. A first multiplier 48 for calculating an average value; and a second variable multiplier 50 for multiplying an output signal of the first multiplier 48 by a coefficient j from the contour amount / coefficient conversion unit 42 and outputting the result.
A third multiplier 52 of a variable coefficient type, which multiplies the video signal output from the one-line delay unit 12 by the coefficient 1-j from the contour amount / coefficient conversion unit 42, and outputs the result; A second adder 54 that adds the output signals of the third multiplier 52 and outputs the added signal as a video signal of the interpolation scanning line.

Next, the operation of FIG. 2 will be described. The level of the contour amount R detected by the contour amount detection unit 30 changes according to the contour component of the image based on the video signal Vi input to the input terminal 10, and the contour amount / coefficient conversion is performed according to the level change of the contour amount R. The coefficients j and 1-j output from the unit 42 to the first and second multipliers 50 and 52 change as shown in FIG. First,
When the coefficients j and 1-j to be multiplied by the second multipliers 50 and 52 change, the first multiplier 4 mixed by the second adder 54
8 and the output signal from the one-line delay unit 12 change. For this reason, as the contour amount R increases, the mixing ratio of the video signal of the upper scanning line in the video signal of the interpolation scanning line input to the double-speed converter 14 increases, and the mixing ratio of the video signal of the lower scanning line increases. Becomes smaller. For example, as shown in FIG.
0 (corresponding to the level 0 of the contour amount R), the mixture ratio of the upper and lower scanning lines is both な っ て, and operates in the same manner as the average value interpolation method of FIG. -J is 0, 1
In the case of (corresponding to level 8 of the contour amount R), the mixing ratio of the upper scanning line is 1 and the mixing ratio of the lower scanning line is 0, which works in the same manner as the zero-order interpolation method in FIG. When the coefficients j and 1-j are 1/2 and 1/2 (corresponding to the level 4 of the contour amount R), the mixing ratio of the upper scanning line is 3/4 and the mixing ratio of the lower scanning line is 1 /. It becomes 4. Therefore, it is possible to perform the interpolation without losing the contour in the contour portion of the image, and to perform the interpolation without noticeable jaggedness in the smoothly changing portion of the image.

In the embodiment shown in FIG. 2, the interpolation point calculation section is constituted by the first and second adders and the first, second and third multipliers. However, the present invention is not limited to this. The input video signal of the scanning line adjacent to the upper side of the interpolation scanning line and the input video signal of the scanning line adjacent to the upper and lower sides of the interpolation scanning line are averaged according to the coefficient output from the contour amount / coefficient conversion unit. Any signal may be used as long as it switches the mixing ratio with the signal and outputs a signal mixed at this mixing ratio as a video signal of the interpolation scanning line.

In the above embodiment, when the contour amount R is large (for example, when the set value S is larger than the set value S), the video signal of the scanning line adjacent above the interpolation scanning line is used as the video signal of the interpolation scanning line. The present invention is not limited to this, and can also be used when the video signal of the scanning line adjacent to the lower side of the interpolation scanning line is used as the video signal of the interpolation scanning line.

In the above-described embodiment, the field interpolation method and the circuit used for converting the input interlaced scanning video signal into the progressive scanning video signal have been described. However, the present invention is not limited to this. Instead, the present invention can also be applied to a field interpolation method and circuit used when converting an input video signal into a video signal whose scanning line is doubled.

[0024]

According to the first and second aspects of the present invention, an input video signal (for example, a video signal for interlaced scanning) is converted into a video signal (video signal for progressive scanning) whose scanning line is doubled. In the field interpolation method used at the time of performing, the contour amount is detected from the input video signals of the scanning lines adjacent to the upper side and the lower side of the interpolation scanning line, and when the contour amount is larger than the set value, the upper side of the interpolation scanning line or The input video signal of the scanning line adjacent to the lower side is used as the video signal of the interpolation scanning line,
When the contour amount is smaller than the set value, a signal obtained by averaging the input video signals of the scanning lines adjacent to the upper and lower sides of the interpolation scanning line is used as the video signal of the interpolation scanning line, so that the contour is not lost at the contour portion of the image. The interpolation can be performed, and the interpolation that smoothly changes at a smoothly changing portion of the image can be performed. For this reason, the outline of the image is not blurred, and the jaggedness is not noticeable in the smoothly changing portion of the image, so that a high-quality image can be expressed.

According to the third and fourth aspects of the present invention, when an input video signal (for example, a video signal for interlaced scanning) is converted into a video signal (video signal for progressive scanning) whose scanning line is doubled. , A one-line delay unit that delays an input video signal by one line, and a contour amount detection unit that detects a contour amount of the input video signal based on the one-line delay signal and the input video signal A comparison unit for comparing the detected contour amount with a set value, and an input video signal of a scanning line adjacent to an upper side or a lower side of the interpolation scanning line and an upper and lower side of the interpolation scanning line in accordance with the comparison output. And an interpolation point calculating unit for switching between an input video signal of an adjacent scanning line and a signal obtained by averaging the input video signal and outputting the signal as an interpolated scanning line video signal. Part with contour It is possible to the interpolation is not lost, smoothly changes in a smooth change portion of the image can be the interpolation can be expressed a high-quality image.

According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the interpolation point calculating section includes an adder for adding the input video signal and the output signal of the one-line delay section, and an adder for the adder. A multiplier for multiplying the signal by a factor of 1/2, and a switcher for switching the multiplied signal of the multiplier and the input video signal in accordance with the comparison output of the comparison unit and outputting as a video signal of an interpolation scanning line. Therefore, the circuit configuration of the interpolation point calculation unit can be simplified.

According to the present invention, when an input video signal (for example, a video signal for interlaced scanning) is converted into a video signal whose scanning line is doubled (a video signal for progressive scanning). In the field interpolation method used in the above, the contour amount is detected from the input video signal of the scanning line adjacent to the upper side and the lower side of the interpolation scanning line, and according to this contour amount, the contour amount is detected above or below the interpolation scanning line. Switching the mixing ratio between the input video signal of the adjacent scanning line and the signal obtained by averaging the input video signals of the adjacent scanning lines above and below the interpolation scanning line,
Since the signal mixed at this mixing ratio is used as the video signal of the interpolation scanning line, interpolation can be performed without losing the outline at the outline of the image, and interpolation that smoothly changes at the smoothly changing portion of the image can be performed. can do. For this reason, the outline of the image is not blurred, and the jaggedness is not noticeable in the smoothly changing portion of the image, so that a high-quality image can be expressed.

According to the eighth and ninth aspects of the present invention, when an input video signal (for example, a video signal for interlaced scanning) is converted into a video signal (video signal for progressive scanning) whose scanning line is doubled. , A one-line delay unit that delays an input video signal by one line, and a contour amount detection unit that detects a contour amount of the input video signal based on the one-line delay signal and the input video signal Unit, a contour amount / coefficient conversion unit that outputs a corresponding pair of coefficients from a plurality of pairs of coefficients according to the level of the detected contour amount, and an interpolation scanning line of the interpolation scan line according to the output coefficients. Switching the mixing ratio between the input video signal of the scanning line adjacent to the upper side or the lower side and the signal obtained by averaging the input video signal of the scanning line adjacent to the upper side and the lower side of the interpolation scanning line, and a signal mixed at this mixing ratio Interpolation run Since there is provided an interpolation point calculation unit for outputting as a line video signal, it is possible to perform interpolation without losing the contour at the contour portion of the image and to smooth the image, as in the invention of claim 6 or 7. It is possible to perform interpolation that changes smoothly at a portion where the change occurs, and to express a high-quality image.

According to a tenth aspect of the present invention, in the invention of the eighth or ninth aspect, a first adder for adding the signal delayed by the one-line delay unit and the input video signal to the interpolation point calculation unit, The first multiplication of the addition signal of the first adder by a factor of 1/2
A multiplier, a second variable multiplier that multiplies the multiplied signal of the first multiplier by one of the coefficients output from the contour amount / coefficient conversion unit, and a contour amount to a signal delayed by the one-line delay unit A variable-variable third multiplier that multiplies the other coefficient output from the coefficient conversion unit, and a second adder that adds the multiplication signals of the second and third multipliers and outputs the result as a video signal of an interpolation scanning line. , The circuit configuration of the interpolation point calculation unit can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a circuit for implementing a field interpolation method according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of a circuit for performing a field interpolation method according to the present invention.

FIG. 3 is an explanatory diagram illustrating an operation of a contour amount / coefficient conversion unit in FIG. 2;

FIG. 4 is a block diagram of a circuit for performing a zero-order interpolation method of a conventional example.

FIG. 5 is a block diagram of a circuit that implements an average value interpolation method in a conventional example.

FIG. 6 is an explanatory diagram for explaining the operation of FIG. 4;

FIG. 7 is an explanatory diagram for explaining the operation of FIG. 5;

[Explanation of symbols]

Reference Signs List 10: input terminal, 12: one-line delay unit, 14: double speed conversion unit, 16: output terminal, 30: contour amount detection unit
32 ... comparator, 34, 44 ... interpolation point calculator, 3
6, 46, 54 ... adder, 38, 48, 50, 52 ...
Multiplier, 40: Switcher, 42: Contour amount / coefficient conversion unit, j, 1-j: A pair of coefficients output from the contour amount / coefficient conversion unit 42, R: Contour amount, S: Set value, Vi:
Digital video signal for interlaced scanning, Vp ...
Digital video signal for progressive scanning.

Claims (10)

[Claims] In a field interpolation method used when converting an input video signal into a video signal whose scanning line is doubled, input of a scanning line adjacent to an upper side and a lower side of an interpolation scanning line. The contour amount is detected from the video signal, and when the contour amount is larger than the set value, the input video signal of the scanning line adjacent above or below the interpolation scanning line is used as the video signal of the interpolation scanning line, and the contour amount is smaller than the set value. A field interpolation method characterized in that a signal obtained by averaging input video signals of scanning lines adjacent to the upper and lower sides of the interpolation scanning line is sometimes used as the video signal of the interpolation scanning line. 2. A field interpolation method used when converting an input interlaced scanning video signal into a progressive scanning video signal, the input of scanning lines adjacent to the upper and lower sides of the interpolated scanning line. The contour amount is detected from the video signal, and when the contour amount is larger than the set value, the input video signal of the scanning line adjacent above or below the interpolation scanning line is used as the video signal of the interpolation scanning line, and the contour amount is smaller than the set value. A field interpolation method characterized in that a signal obtained by averaging input video signals of scanning lines adjacent to the upper and lower sides of the interpolation scanning line is sometimes used as the video signal of the interpolation scanning line. 3. A one-line delay unit for delaying the input video signal by one line in a field interpolation circuit used when converting an input video signal into a video signal whose scanning line is doubled. A contour amount detection unit for detecting a contour amount of the input video signal based on the signal delayed by the one-line delay unit and the input video signal, and a contour value detected by the contour amount detection unit as a set value. A comparison unit to be compared, and an input video signal of a scanning line adjacent to the upper side or lower side of the interpolation scanning line and an input image signal of a scanning line adjacent to the upper side and lower side of the interpolation scanning line according to the comparison output of the comparison unit A field interpolation circuit for switching between a signal obtained by averaging the signal and outputting the signal as a video signal of an interpolation scanning line. 4. A one-line delay section for delaying the input video signal by one line in a field interpolation circuit used when converting an input interlaced scanning video signal into a progressive scanning video signal. A contour amount detection unit for detecting a contour amount of the input video signal based on the signal delayed by the one-line delay unit and the input video signal, and a contour value detected by the contour amount detection unit as a set value. A comparison unit to be compared, and an input video signal of a scanning line adjacent to the upper side or lower side of the interpolation scanning line and an input image signal of a scanning line adjacent to the upper side and lower side of the interpolation scanning line according to the comparison output of the comparison unit A field interpolation circuit for switching between a signal obtained by averaging the signal and outputting the signal as a video signal of an interpolation scanning line. 5. An interpolation point calculating section, comprising: an adder for adding an input video signal and an output signal of a one-line delay section; a multiplier for multiplying the added signal of the adder by a factor of 、; 5. The field interpolation circuit according to claim 3, further comprising a switch for switching between the multiplied signal of the multiplier and the input video signal in accordance with the comparison output of the comparing section, and outputting the signal as a video signal of the interpolation scanning line. 6. A field interpolation method used when converting an input video signal into a video signal whose scanning line is doubled, wherein input signals of scanning lines adjacent to the upper and lower sides of the interpolation scanning line are input. A contour amount is detected from a video signal, and an input video signal of a scanning line adjacent to an upper side or a lower side of an interpolation scanning line and an input image signal of a scanning line adjacent to an upper side and a lower side of the interpolation scanning line are detected in accordance with the contour amount. A field interpolation method characterized by switching a mixing ratio with a signal obtained by averaging a signal, and forming a signal mixed at the mixing ratio as a video signal of an interpolation scanning line. 7. A field interpolation method used when converting an input interlaced scanning video signal into a progressive scanning video signal, wherein an input of a scanning line adjacent to an upper side and a lower side of an interpolation scanning line is input. A contour amount is detected from a video signal, and an input video signal of a scanning line adjacent to an upper side or a lower side of an interpolation scanning line and an input image signal of a scanning line adjacent to an upper side and a lower side of the interpolation scanning line are detected in accordance with the contour amount. A field interpolation method characterized by switching a mixing ratio with a signal obtained by averaging a signal, and forming a signal mixed at the mixing ratio as a video signal of an interpolation scanning line. 8. A one-line delay unit for delaying the input video signal by one line in a field interpolation circuit used when converting an input video signal into a video signal whose scanning line is doubled. A contour amount detecting unit for detecting a contour amount of the input video signal based on the signal delayed by the one-line delay unit and the input video signal, and a contour amount detected by the contour amount detecting unit; A contour amount / coefficient conversion unit that outputs a pair of coefficients corresponding to a plurality of preset pairs of coefficients, and an upper or lower side of the interpolation scanning line according to the coefficient output by the contour amount / coefficient conversion unit. The mixing ratio between the input video signal of the adjacent scanning line and the signal obtained by averaging the input video signals of the scanning lines adjacent above and below the interpolation scanning line is switched, and the signal mixed at this mixing ratio is used as the interpolation scanning line. Interpolation output as a video signal Field interpolation circuit, characterized by comprising; and a calculation unit. 9. A one-line delay unit for delaying the input video signal by one line in a field interpolation circuit used when converting an input interlaced scanning video signal into a progressive scanning video signal. A contour amount detecting unit for detecting a contour amount of the input video signal based on the signal delayed by the one-line delay unit and the input video signal, and a contour amount detected by the contour amount detecting unit; A contour amount / coefficient conversion unit that outputs a pair of coefficients corresponding to a plurality of preset pairs of coefficients, and an upper or lower side of the interpolation scanning line according to the coefficient output by the contour amount / coefficient conversion unit. The mixing ratio between the input video signal of the adjacent scanning line and the signal obtained by averaging the input video signals of the scanning lines adjacent above and below the interpolation scanning line is switched, and the signal mixed at this mixing ratio is used as the interpolation scanning line. Video signal Field interpolation circuit, characterized by comprising; and a interpolation point calculation unit among which to output. 10. A first adder for adding a signal delayed by a one-line delay unit and an input video signal, said interpolation point calculating unit;
A first multiplier for multiplying the addition signal of the first adder by 係数 coefficient, and a coefficient variable type for multiplying the multiplication signal of the first multiplier by one coefficient output from the contour amount / coefficient conversion unit A third multiplier of a variable coefficient type for multiplying the signal delayed by the one-line delay unit with the other coefficient output from the contour amount / coefficient conversion unit; 10. The field interpolation circuit according to claim 8, further comprising a second adder for adding the multiplication signals of the multipliers and outputting as a video signal of the interpolation scanning line.