JPH0937214A - Progressive scanning conversion method and progressive scanning converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a progressive scanning conversion method and a progressive scanning converter by which effective scanning line interpolation is applied even to an oblique edge and a slant line. SOLUTION: In the case of converting a video signal of interlace scanning into a video signal of progressive scanning, an original pixel selection circuit 101 selects an object of sets of original pixels from which an absolute value of a difference of the pixels among sets of original pixels in point symmetrical relation around an interpolation pixel, corrects the difference absolute values based on edge information of the original pixels, detects sets of the original pixels minimizing the corrected difference absolute value and a filter circuit 108 generates the interpolation pixel based on the set of the original pixels.

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 method and a progressive scan conversion device for converting an interlaced scan video signal into a progressive scan video signal.

[0002]

2. Description of the Related Art Conventionally, as a progressive scan conversion apparatus in a progressive scan conversion technique for converting a 2: 1 interlaced scan (interlaced scan) video signal into a 1: 1 progressive scan video signal, an IDTV (improved definiti)
There is a motion adaptive scanning line interpolation circuit used in an on television reception circuit. For details of the motion adaptive scanning line interpolation circuit, see References, Television Society, Television Image Information Engineering Handbook, P. 8
99-P. 900 (1990). Among them, as the line scanning line interpolating circuit, a double writing line scanning line interpolating circuit that directly uses the adjacent scanning lines and an average line scanning line interpolating circuit that uses the average of the adjacent scanning lines have been proposed. Further, Japanese Laid-Open Patent Publication No. 6-153169 discloses a line scanning line interpolation circuit for averaging pixel values in a diagonal direction having a high correlation for the purpose of preventing resolution deterioration of a diagonal edge.

The operation of the conventional progressive scan conversion apparatus will be described below with reference to the drawings.

FIG. 6 is a view showing an image displayed on the display. Reference characters a to t are original pixels on an original line displaying an interlaced scanning video signal, and p0 to p9 are interpolation pixels on an interpolation line created to obtain a progressive scanning video signal. Here, the pixel value of the original pixel (corresponding to the brightness value on the display) is a = b = c = d = e = 100,
f = g = h = i = j = 0, k = 1 = m = 100, n = o
= P = q = r = s = t = 0. The image shown in FIG. 6 is f
It is an oblique edge having an inclination of −n (hereinafter, abbreviated as f−n edge), and the upper left direction is white and the lower right direction is black from the f−n edge. In such a case,
Consider the pixel value when interpolation is performed by the circuit of the method.

First, in the case of the double writing line scanning line interpolation circuit, since the adjacent scanning lines are used as they are, the pixel value of the interpolation pixel is p0 = p1 = p2 = p3 = p4 = 100, p5.
= P6 = p7 = p8 = p9 = 0 and an interpolation line is created. Next, in the case of the average line scanning line interpolation circuit, since the average of adjacent scanning lines is used, the pixel value of the interpolation pixel is p
0 = p1 = p2 = 100, p3 = p4 = 50, p5 = p
6 = p7 = p8 = p9 = 0. Further, in the case of a line scanning line interpolation circuit that averages pixel values in a diagonal direction with high correlation, the correlation is evaluated based on the difference value between the original pixels in the vertical direction and the diagonal direction centered on the interpolated pixel. The direction in which the difference value is smallest is the direction with high correlation, and the average value of the original pixels in that direction is the pixel value of the interpolation pixel. The directions to be evaluated at that time are five directions to the left and right with the vertical direction as the center. Therefore, p0 = p1 = 100, p2 selects either the cm direction or the dl direction, p2 = 100, p3 selects the em direction, and p3 =
100, p4 selects the f-n direction, p4 = 0, p5 = p
6 = 0.

[0006]

However, in the progressive scan conversion apparatus using the line scanning line interpolation circuit according to the conventional three methods as described above, at the edge portion of the image,
There is a problem that the following image quality deterioration occurs.

In the case of the double writing line scanning line interpolation circuit, p3 = p4 = 100 at the fn edge as shown in FIG.
That is, since it becomes white, it is jagged. As a result, line flicker that occurred during interlaced display is not reduced at all.

In the case of the average line scanning line interpolation circuit, p3 =
p4 = 50, that is, gray. As a result, although the line flicker is slightly reduced, the resolution in the diagonal direction is deteriorated and the fn edge is blurred.

On the other hand, in the case of a line scanning line interpolating circuit for averaging pixel values in a diagonal direction with high correlation, p3 =
100, p4 = 0, and the f-n edge is completely interpolated. However, in the case of the diagonal line A like the image shown in FIG. 7, p0, p1, p2, p3, p5, p6, p7, p
The pixel values of the interpolated pixels of 8 and p9 are 100, but p4 is br direction, cq direction, dp direction, dp direction, and f.
The difference value of the original pixel, that is, the evaluation result of the correlation is the same in both the −n direction and the hl direction, and the direction cannot be specified. Even in such a case, even if the algorithm is such that the intermediate direction is selected, the pixel value of p3 becomes 100 by selecting the dp direction. Similarly for p5,
c-s direction, d-r direction, eq direction, g-o direction, i
The evaluation results of the correlation in the −m direction are equal, and p4 = 10
It becomes 0. As a result, the diagonal line A is cut and is not interpolated at all.

In the case of the diagonal line A in FIG. 7, p4 = p5 = 50 in the average line scanning line interpolating circuit, which causes blurring but does not cause cutting. As described above, the line scanning line interpolation circuit that averages pixel values in the diagonal direction with high correlation is
Interpolation is very effectively performed on the diagonal edge portion of a graphic having a relatively large area, but it may not be possible to interpolate effectively on thin diagonal lines.

The present invention solves the above problems and provides a progressive scan conversion method and a progressive scan conversion device capable of performing effective scan line interpolation even for a diagonal edge or a diagonal line generated by a surface. The purpose is to

[0012]

In order to achieve the above object, the progressive scan conversion apparatus of the present invention, when converting an interlaced scan video signal into a progressive scan video signal, the interlaced scan one field video. In a progressive scan conversion device that creates an interpolation pixel for the conversion based on an original pixel obtained by sampling a signal in a grid pattern, an original that selects a set of original pixels having a point symmetry relationship with the interpolation pixel being created as a center. Pixel selection means, correlation value calculation means for calculating the correlation value of the pixel values of the set of original pixels selected by the original pixel selection means, and edge information for detecting edge information in each original pixel of the set of original pixels Detection means, correlation value correction means for correcting the correlation value calculated by the correlation value calculation means using the edge information detected by the edge information detection means, and the phase Of the corrected correlation values obtained from the value correction means, a tilt detection means for detecting the tilt direction of the set of original pixels having the highest correlation, and a filter means for creating an interpolated pixel for the conversion, Based on a predetermined number of original pixels in the tilt direction detected by the tilt detection means,
The filter means is configured to create an interpolated pixel for the conversion.

[0013]

According to the structure of the present invention, when an interlaced scanning video signal is converted into a progressive scanning video signal, a candidate of a set of original pixels for which a correlation value of pixel values is obtained is centered on an interpolation pixel. Select from a set of original pixels in a symmetric relationship,
In each set of original pixels, the correlation value of pixel values is calculated, and based on the edge information of each original pixel of each set of original pixels,
The correlation value is corrected, and the interpolated pixel is created based on the set of original pixels having the highest correlation with the corrected correlation value.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A progressive scan conversion method and a progressive scan conversion apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

First, the progressive scan conversion method of this embodiment will be described. FIG. 4 shows a two-dimensional image centered on the interpolated pixels displayed on the display. Based on FIG. 4,
The definition of the vertical direction and the diagonal direction centering on the interpolation pixel will be described. For a two-dimensional image as shown in FIG. 4, the edge information has a two-dimensional spread in the horizontal and vertical directions. However, the two-dimensional edge information can be decomposed into the one-dimensional edge information in the horizontal direction and the one-dimensional edge information in the vertical direction. Therefore, the one-dimensional edge information will be described for simplification of description. FIG.
Shows the type of one-dimensional edge information, and based on FIG.
The definition of edge information will be described. In addition, a procedure for creating interpolated pixels in the progressive scan conversion method of the present embodiment will be described based on the two-dimensional image displayed on the display shown in FIG.

In FIG. 4, it is assumed that the interpolation pixel for obtaining the progressive scan conversion signal is p, and the original pixels obtained by sampling the interlaced scanning video signal in a grid pattern are a to n. Interpolation pixel p
On the other hand, the original pixels d and k existing in the vertical direction have an inclination of 0, and the original pixel e existing in a direction inclined by one pixel to the right,
The direction of j is defined as the inclination +1. Similarly, the original pixels f, i
Is +2, the original pixels g and h are +3, the original pixels c and l are −1, the original pixels b and m are −2, and the original pixels a and n are Define as -3.

In FIG. 5, a and b are interlaced scanning video signals, which are a dot clock fs (MHz) in the horizontal direction and a line clock fh (kHz) in the vertical direction. It is the pixel value (corresponding to the luminance value on the display) of the original pixel sampled in a uniform manner. The original pixel a corresponds to the pixel one dot clock before the original pixel b in the horizontal direction, and the pixel one line before in the vertical direction. The edge information Edge (b) in the original pixel b is defined as the difference value between the pixel value of the original pixel b and the pixel value of the original pixel b. Further, when the pixel value of the original pixel b is larger than the pixel value of the original pixel a, that is, when the edge information Edge (b) is positive, the edge 1 is set, and the pixel value of the original pixel b is set to the pixel value of the original pixel a. When it is smaller, that is, when the edge information Edge (b) is negative, it is edge 2, and when there is no difference between the pixel value of the original pixel b and the pixel value of the original pixel a, that is, the edge information Edge (b) is 0. The case is defined as edge 3. Edge 1 and edge 2
In, the larger the absolute value of the edge information Edge (b), the larger the inclination of the edge, and the smaller the absolute value, the smaller the inclination of the edge. That is, a large edge inclination means that the image has a steep edge, and a small edge inclination means that the image has a gentle edge.

In FIG. 6, a to t are original pixels obtained by sampling the interlaced scanning video signal in a grid pattern, p0 to p.
Reference numeral 9 is an interpolation pixel on an interpolation line created to obtain a video signal of progressive scanning. Here, the pixel value of the original pixel (corresponding to the brightness value on the display) is a = b = c = d =
e = 100, f = g = h = i = j = 0, k = l = m = 1
00 and n = o = p = q = r = s = t = 0. The image shown in FIG. 6 has an oblique edge (hereinafter, referred to as f
It is abbreviated as -n edge), and the upper left direction is white and the lower right direction is black from the fn edge.

Interpolation pixels p0 to p9 are sequentially created for such an image, and the creation procedure is performed in the following steps.

In step 1, a total of 7 directions from inclinations -3 to +3 are set as inclination candidates. In step 2, the absolute difference values of the pairs of original pixels that exist in the directions of the seven inclination candidates identified in step 1 and have a point symmetry centered on the interpolated pixel are obtained. In step 3, edge information is obtained for the original pixel for which the absolute difference value is obtained. The edge information obtains a difference value from the original pixel one clock before in the horizontal direction and a difference value from the original pixel one line before in the vertical direction. In step 4, the difference absolute value obtained in step 2 is corrected based on the edge information obtained in step 3. Similarly to the case where the absolute difference value is obtained, the edge information in the horizontal direction and the vertical direction of the set of original pixels that exist in the direction of the seven inclination candidates identified in step 1 and have a point-symmetrical relationship with the interpolation pixel as the center. The absolute value of the difference is calculated. In the original pixel in the direction in which the diagonal edge exists, not only the pixel values of the original pixel are similar, but also the edge information is similar. Regarding the similarity of edge information, when the presence / absence of an edge is considered, the similarity, that is, the correlation, should be higher when the edge is present.
Further, if the directionality of edges is similar, the correlation should be even higher. For this reason, when there is an edge and the directionality is similar, when the edge information of the original pixel for which the absolute value of the edge information difference is obtained is one edge 1 or two edges in FIG. The difference absolute value of the edge information is corrected by subtracting a certain value α, and when there is no edge, that is, in the case of edge 3 in FIG. 5, the difference absolute value of the edge information is not corrected. The absolute difference value of the edge information obtained as described above is added to the absolute difference value obtained in step 2. Step 5
In step 1, the set of original pixels having the smallest difference absolute value corrected in step 4 is evaluated as the set of original pixels having the highest correlation. If the smallest set cannot be specified as one, the set of original pixels having a slope of 0 is adopted. In step 6, the pixel values of the set of original pixels having the highest correlation found in step 5 are averaged to obtain the pixel value of the interpolated pixel.

The pixel values of the interpolated pixels p0 to p9 are obtained according to the procedure of steps 1 to 6 as described above.

First, regarding the procedure for creating the interpolation pixel p3,
This will be described in detail with reference to FIG. First, tilt-3
A total of 7 directions up to +3 are set as inclination candidates. The above-described set of seven original pixel candidates of the inclination are the inclination a-3 and the inclination −a.
2 b and p, slope -1 c and o, and slope 0 d and n
And e and m of inclination +1 and f and l of inclination +2 and inclination +
3 g and k. When the absolute difference value is calculated for each of the set of seven original pixels of inclination candidates, inclinations −3 to 0 and inclination +
In the range of 2 to +3, the value is 100, and only the slope +1 is 0. Original pixel a
.. g, k to q, the original pixel a to
For e, k to m, and p to q, the difference value is 0 in both the horizontal and vertical directions, and for the original pixels f and n, the difference value is -100 and the original pixel g and in both the horizontal and vertical directions. Regarding o, 0 in the horizontal direction and −100 in the vertical direction. The absolute difference values of the edge information in the set of seven original pixel candidates of inclination are 0 in both the horizontal and vertical directions for inclinations -3 to -2 and +1 and 0 in the horizontal direction for inclinations -1 to 0 and +3. Yes, but 100 in the vertical direction, tilt +
For 2, the value is 100 in both the horizontal and vertical directions.
When each of these edge information difference absolute values is added to the difference absolute value of each set of seven original pixels of inclination candidates,
The slopes -3 to -2 remain unchanged at 100, the slopes -1 to 0, +
3, the edge information difference value in the vertical direction is added to 200,
The slope +1 remains unchanged at 0, the slope +2 becomes 300 by adding the edge information difference values in the horizontal and vertical directions, the slopes 0 and +2 become 200, and the slope +1 becomes 0. From the above, it is the set of the original pixel e and the original pixel m having the inclination +1 that is the smallest among the absolute difference values corrected by the edge information. Therefore, the pixel value of the interpolation pixel p3 is 100, which is the average value of the pixel values of the original pixel e and the original pixel m.

Thereafter, interpolation pixels p4 and p5 are also created by the same procedure. Regarding the interpolated pixel p4, the set of seven original pixels of the inclination candidates is b and r of inclination-3 and c of inclination-2.
q, d and p of inclination -1, e and o of inclination 0, and inclination +
F and n of 1 and g and m of +2 and h and l of +3
And When the absolute difference value is calculated for each of the seven sets of original pixels of the inclination candidate, 100 is obtained for the inclinations -3 to 0 and +2 to +3, and 0 is obtained only for the inclination +1. Correction is performed using the absolute value of the edge information difference. However, when the interpolation pixel p4 is created, the original pixel f and the original pixel n are obtained for the inclination +1.
Since the edge information of is the edge 2 in FIG. 4 in both the horizontal and vertical directions, a certain value α is subtracted from the difference absolute value of the edge information for each of the horizontal and vertical edge information. Here, α = 5 for simplification of description, but α may be any number as long as it is a positive number. For this reason, the absolute value of the edge information difference with respect to the inclination +1 becomes −10 because 5 is subtracted from each of the edge information in the horizontal direction and the edge information in the vertical direction. Also, the slopes -3 to -1, +3 are 100, and the slopes 0 and +2 are 200. From the above, the set of the original pixel f and the original pixel n having the inclination +1 is adopted, and the pixel value of the interpolation pixel p4 is the original pixel f.
And 0, which is the average value of the pixel values of the original pixel n. Regarding the interpolated pixel p5, the absolute value of the difference between the original pixels corrected by the edge information is 100 for the slopes -3 to -1, +3, 200 for the slopes 0 and +2, and -5 for the slope +1 and the slope +
The set of the original pixel g and the original pixel o of 1 is adopted, and the interpolation pixel p5
The pixel value of is 0, which is the average value of the pixel values of the original pixel g and the original pixel o. The other interpolation pixels p0 to p2 and p6 to p9 are created in the same procedure, and the pixel values of the interpolation pixels p0 to p2 are 100, and the pixel values of the interpolation pixels p6 to p9 are 0.

The fn edge is completely interpolated as described above. As in the image shown in FIG. 7, interpolation pixels p0 to p9 in the case of diagonal line A are obtained.

First, the procedure for creating interpolation pixels for the interpolation pixels p3 to p6 will be described. For the interpolation pixel p3,
The absolute values of differences between original pixels are -3 to -2, +1 is 0, -1 to 0 and +2 to +3 are 100. On the other hand, when the correction is performed based on the edge information, the original pixel a has no edge with respect to the inclination -3, but the original pixel q is vertically oriented as shown in FIG.
100 is added because the edge 1 of
The original pixel b has no edge for the inclination -2, but the original pixel p has the edge 1 in both the vertical direction and the horizontal direction, so 200 is added to the original pixel p and 200 for the inclination -1. Has no edges, but since the original pixel o has an edge 2 in the vertical direction, 100 is added to 200, and for an inclination of 0, the original pixel d has no edges, but the original pixel n has a vertical direction. Since there is an edge 2 in the horizontal direction, 200 is added to add 300, and for an inclination of +1 there is no edge in both the original pixel e and the original pixel m, so there is no change, 0, inclination +2
, The original pixel f has edges 2 in both the vertical and horizontal directions, and the original pixel l has no edges, so 200 is added to 300, and for the inclination +3, the original pixel g is only in the vertical direction. Since the edge 2 exists and the original pixel k has no edge, 100 is added to be 200. From the above, the set of the original pixel e and the original pixel m having the inclination +1 is adopted, and the pixel value of the interpolation pixel p3 becomes 100, which is the average value of the pixel values of the original pixel e and the original pixel m.

Regarding the interpolated pixel p4, the absolute value of the difference between the original pixels is 0 for slopes -3 to -1, +1 and +3, and 0 for slope +.
2 becomes 100. On the other hand, when the correction is performed using the edge information, the slope-3 is 0, the slope-2 is unchanged.
, The original pixel c has no edges, but the original pixel q has an edge 1 in the vertical direction, so 100 is added and 1 is added.
The original pixel d has no edge with respect to 00 and the inclination of -1, but since the original pixel p has the edge 1 in both the vertical direction and the horizontal direction, 200 is added to the original pixel p and 200 with respect to the inclination of 0. The pixel e has no edge, but the original pixel o has edge 2 in the vertical direction, so 100 is added to 200,
For the inclination +1, the original pixel f has the edge 2 in the vertical direction and the horizontal direction, and the original pixel n also has the edge 2 in the vertical direction and the horizontal direction. For +2, the original pixel g has an edge 2 only in the vertical direction, and the original pixel m has no edge.
0 is added to give 200, and for inclination +3, the original pixel h has an edge 1 in both the vertical and horizontal directions, and since the original pixel l has no edges, 200 is added to give 200.
Becomes From the above, the original pixel f and the original pixel n having a slope of +1
Is adopted, and the pixel value of the interpolation pixel p4 becomes 0 which is the average value of the pixel values of the original pixel f and the original pixel n.

For the interpolated pixel p5, the absolute value of the difference between the original pixels after the correction based on the edge information is 0 for the slopes -3 and -2, 100 for the slope -1, 500 for the slope 0, and -500 for the slope +1.
5, the slope +2 is 500, and the slope +3 is 100, and the combination of the original pixel g and the original pixel o having the inclination +1 is adopted, and the pixel value of the interpolation pixel p5 is the average of the pixel values of the original pixel g and the original pixel o. The value is 0.

For the interpolated pixel p6, the absolute value of the difference between the original pixels after the correction based on the edge information is 0 for inclinations -3 and -2, 300 for inclination -1, 300 for inclination 0, and -for inclination +1.
10, the gradient +2 is 300, the gradient +3 is 300, and a pair of the original pixel h and the original pixel p having the inclination +1 is adopted, and the pixel value of the interpolation pixel p6 is the average of the pixel values of the original pixel h and the original pixel p. The value is 100.

The other interpolation pixels p0 to p2 and p7 to p9 are created in the same procedure, and the interpolation pixels p0 to p2, p
The pixel value of 7 to p9 is 100.

The diagonal line A is completely interpolated as described above. Further, as in the image shown in FIG. 8, interpolation pixels p0 to p9 in the case of a diagonal line B, which is steeper than the diagonal line A, are obtained.

First, the procedure for creating interpolation pixels for the interpolation pixels p3 to p6 will be described. For the interpolation pixel p3,
The absolute value of the difference between original pixels is 0 for slopes -3 to -1, +2, 100 for slopes 0 to +1 and +3. When the correction based on the edge information is applied to this, the original pixel a
Has no edge, but 100 is added to the original pixel q because the edge 1 of FIG.
For 0, since both the original pixel b and the original pixel p have no edges, 0 is unchanged, and for the inclination -1, the original pixel c has no edges, but the original pixel o has an edge 1 in the horizontal direction. Therefore, 100 is added to 100, and the original pixel d has no edge when the inclination is 0, but since the original pixel n has the edge 2 in the vertical direction, 100 is added to 200 and the inclination is +1.
, The original pixel e has no edge, but the original pixel m has edge 2 in both the vertical direction and the horizontal direction.
Is added to 300, and with respect to the inclination +2, the original pixel f and the original pixel l have no edges, and therefore 0 does not change, and the inclination +3
On the other hand, since the original pixel g has the edge 2 in both the vertical direction and the horizontal direction, and the original pixel k has no edge, 200 is added to become 300. In this case, slope -2 and slope +2
Since the absolute value of the difference between both is 0 and cannot be specified, the set of the original pixel b and the original pixel p having the inclination −2, the inclination +
Both the original pixel f and the original pixel 1 which are 2 are adopted.
The pixel value of the interpolation pixel p3 is an average value of the pixel values of a total of 4 pixels of the original pixel b, the original pixel p, the original pixel f, and the original pixel l 10
It becomes 0.

For the interpolated pixel p4, the absolute value of the difference between the original pixels is -3 to 0, +2 is 0, and +1 and +3 are 1.
00. When the correction is performed based on the edge information, the original pixel b has no edge for the slope -3,
Since the original pixel r has the edge 1 in the vertical direction, 100 is added to obtain 100, and the original pixel c has no edge for the inclination -2, but the original pixel q has the edge 1 in the vertical direction. 100 is added to 100, the original pixel d and the original pixel p for the slope −1 have no edges because there is no edge, and for the slope 0, the original pixel e has no edges. Since the pixel o has an edge 1 in the horizontal direction, 10
When 0 is added to 100 and the inclination is +1, the original pixel f
Has no edge, but since the original pixel n has an edge 2 in the vertical direction, 100 is added to 200, and for an inclination +2, the original pixel g has an edge 2 in both the vertical direction and the horizontal direction. Similarly, the pixel m has an edge 2 in both the vertical direction and the horizontal direction, so that 10 is subtracted and the slope is +10.
3, the original pixel h has an edge 2 in the vertical direction,
Since the original pixel l has no edge, 100 is added and 20
It becomes 0. From the above, the set of the original pixel g and the original pixel m having the inclination +2 is adopted, and the pixel value of the interpolation pixel p4 is the original pixel g.
And 0, which is the average value of the pixel values of the original pixel m.

Regarding the interpolated pixel p5, the absolute value of the difference between the original pixels after correction by the edge information is 0 for slope-3, 100 for slope-2, 100 for slope-1, 100 for slope 0, and 0 for slope +.
1 is 400, inclination +2 is −5, inclination +3 is 400, and a set of original pixel h and original pixel n with inclination +2 is adopted, and the pixel value of interpolation pixel p5 is the pixel of original pixel h and original pixel n. The average value is 0.

For the interpolated pixel p6, the absolute value of the difference between the original pixels after correction by the edge information is 0 for slope-3, 0 for slope-2, 100 for slope-1, 300 for slope 0, and 300 for slope +.
1 is 200, inclination +2 is −5, inclination +3 is 200, and a set of original pixel i and original pixel o with inclination +2 is adopted, and the pixel value of interpolation pixel p6 is the pixel of original pixel i and original pixel o. The average value is 100.

The other interpolation pixels p0 to p2 and p7 to p9 are created by the same procedure, and the interpolation pixels p0 to p2, p
The pixel value of 7 to p9 is 100.

The diagonal line B is completely interpolated as described above. By the above method, effective scanning line interpolation can be performed even for an oblique edge or an oblique line generated by a surface.

In the above embodiment, when the pixel value of the interpolation pixel is obtained, the pixel values of the original pixels closest to the interpolation pixel existing in the interpolation direction determined to have the highest correlation are averaged. By increasing the number of original pixels existing in the interpolation direction, the pixel value of the interpolation pixel can be obtained with higher accuracy. That is, the pixel values of a total of four original pixels of the two original pixels on the upper two lines and the two original pixels on the lower two lines existing in the interpolation direction are multiplied by predetermined coefficients, respectively, and added to obtain the interpolated pixel. It is sufficient to obtain the pixel value of.

Further, although the correlation is evaluated based on the difference value of the pixel values of the original pixels, it is also possible to increase the number of pixels of the original pixels.
It can be implemented similarly.

Next, the progressive scan conversion apparatus of this embodiment will be described. Before explaining this progressive scan conversion device,
First, the tilt direction used later is defined according to FIG.

FIG. 3 is a two-dimensional view of the interlaced scanning video signal in the field centering on the interpolation signal for obtaining the progressive scanning video signal. In FIG. 3, it is assumed that the interpolation signal is p and the interlaced scanning video signal is the original signals a to n. The original signals d and k existing in the vertical direction with respect to the interpolation signal p have a slope of 0, the original signals e and j existing in the direction inclined by one pixel to the right have a slope of +1, and the original signals f and i have The direction is +2, the directions of the original signals g and h are +3, the directions of the original signals c and l are −1, the directions of the original signals b and m are −2, and the directions of the original signals a and n are − Defined as 3.

FIG. 1 is a block diagram showing the main part of the progressive scan conversion apparatus of this embodiment for realizing the progressive scan conversion method.
FIG. 2 shows an intra-field interpolation circuit 1 as a first embodiment.
14 is a block diagram for explaining details of the operation of FIG.
In addition, the intra-field interpolation circuit 114 according to the second embodiment is
3 is a block diagram for explaining details of the operation of FIG.

In FIG. 1, the input signal is a video signal of 2: 1 interlaced scanning at a sampling frequency fs (M
Is a digital video signal (original signal) sampled at a sampling frequency of 2 × f.
It is a video signal of s (MHz) 1: 1 progressive scanning.

An input signal is a 1H memory (1H corresponds to one line of an interlaced scanning video signal) 110, 11
Delayed by 1, 112, (y-1) line, y line,
Original signals on four lines (y + 1) line and (y + 2) line are simultaneously obtained. The original signal on each line is stored in a RAM (Random Access Memory) 107. At the same time, the original signal selection circuit 101 selects an original signal that is a slope candidate from the original signals of the y line and the (y + 1) line. The correlation value calculation circuit 102 calculates the correlation value between the original signals of the selected slope candidates. At the same time,
In the edge information detection circuit 103, the y line and (y +
1) Detect horizontal and vertical edge information of each original signal of a line. The correlation value correction circuit 104 corrects the correlation value calculated by the correlation value calculation circuit 102 based on the detected edge information. The corrected correlation value is input to the inclination detection circuit 105, the inclination direction having the highest correlation is detected and output as the interpolation direction. The detected interpolation direction is input to the address calculation circuit 106.

The address calculation circuit 106 stores the original signal necessary for calculating the interpolation signal in the RAM 10.
The address of 7 is calculated. The original signals necessary to calculate the interpolated signal are (y-1) line, y line, (y +
1) line and (y + 2) line, which are the four original signals in the interpolation direction detected by the inclination detection circuit 105 centering on the calculated interpolation signal. Address calculation circuit 106
Thus, the four original signals retrieved from the RAM 107 are weighted and added to a predetermined coefficient of the filter coefficient memory 109 by the filter circuit 108 as a filter means and input to the time axis conversion circuit 113 as an interpolation signal. . In the time-axis conversion circuit 113, the original signal and the interpolated signal are each time-double compressed in the time axis and alternately output for each line to obtain a progressively scanned video signal.

Next, the operation of the intra-field interpolation circuit 114 as the first embodiment will be described in detail with reference to FIG.

In FIG. 2, the input signal delayed by the 1H memory 111 is the original signal on the y line, and is a 1D delay device (1D corresponds to one pixel in interlaced scanning) 201.
The original signals a to g are obtained by delaying at .about.206. The original signals a to g correspond to a to g on the original line y shown in FIG.
The input signal delayed by the 1H memory 112 is (y + 1)
The original signal on the line is delayed by the 1D delay units 208 to 213 to obtain original signals h to n. The original signals h to n correspond to h to n on the original line (y + 1) shown in FIG. The subtractors 221 to 227 cause the slopes -3 to + shown in FIG.
The difference value for the set of 3 original signals is obtained. The calculated difference value is converted into an absolute value by the absolute value circuit 228, and is input to the correlation value correction circuits 229 to 235 as a correlation value indicating the correlation.

On the other hand, the edge information in the horizontal direction of the original signal on the y line is calculated as a difference value with the adjacent original signal by using the subtractors 236 to 242. Further, the horizontal edge information of the original signal on the (y + 1) line is also subtracted from the subtracters 243 to 243.
249 is used to calculate the difference value. The absolute value circuit 2 is based on the horizontal edge information of the original signal on the y line and the horizontal edge information of the original signal on the (y + 1) line.
The correlation value calculated in 28 is used as the correlation value correction circuits 229-2.
Correct with 35.

Correlation value correction processing in the correlation value correction circuits 229 to 235 is similar to the case of calculating the difference value with respect to the set of original signals having the slopes -3 to +3, and the slopes -3 to +3.
The difference value of the edge information in the horizontal direction corresponding to each set of the original signals is calculated. The calculated difference value of the horizontal edge information is converted into an absolute value, and the correlation value is corrected based on this difference absolute value. The correction of the correlation value only adds the absolute difference value of the horizontal edge information to the correlation value, but when the absolute difference value of the horizontal edge information is small,
The correction method is slightly different. The fact that the difference absolute value of the edge information is small means that the same edge exists. However, even if the difference absolute value of the same edge information is small, the meaning of the correlation is slightly different depending on the presence or absence of the edge. If the difference absolute values of the edge information are the same, and one has no edge and the other has an edge, the edge slope, that is, the directionality of the edge is searched between the adjacent original signals. In the case of, the correlation should be higher. Therefore, when the absolute difference value of the edge information is small and there is an edge, a certain value α is subtracted from the correlation value to which the absolute difference value of the edge information is added. Any configuration may be used as long as the circuit configuration conforms to the processing content. Even if this correlation value correction circuit is configured by a look-up table memory, the same effect can be obtained.

As described above, the correlation value correction circuits 229 to 235.
The correlation value corrected in (1) is input to the correlation value correction circuits 250 to 256 which correct the edge information in the vertical direction.

Further, the edge information in the vertical direction of the original signal on the y line is calculated as a difference value with the original signal on the (y-1) line located immediately above the original signal on the y line by using the subtracters 257 to 263. . Further, the edge information of the original signal on the (y + 1) line in the vertical direction is subtracted from the subtracter 264.
~ 270 is used to calculate the difference value. Correlation values corrected by the horizontal edge information based on the vertical edge information of the original signal on the y line and the vertical edge information of the original signal on the (y + 1) line are corrected by the correlation value correction circuits 250 to 256. To do.

Correlation value correction processing contents in the correlation value correction circuits 250 to 256 are similar to the correlation value correction processing contents based on the horizontal edge information.

In the evaluation circuit 271, the correlation value Dr _-3 corrected by the horizontal edge information and the vertical edge information is used.
The minimum value of ~ Dr ₃ is evaluated. When the correlation value Dr _-3 is evaluated as the minimum value, the interpolation direction is the slope − shown in FIG.
3, and -3 is output as the interpolation direction P. Similarly, in the case of the correlation value Dr ₋₂ , the interpolation direction P = −2, in the case of the correlation value Dr ₋₁ , the interpolation direction P = −1, and in the case of the correlation value Dr ₀ , the interpolation direction P = 0, In the case of the correlation value Dr ₁ , the interpolation direction P = 1, in the case of the correlation value Dr ₂ , the interpolation direction P = 2, and in the case of the correlation value Dr ₃ , the interpolation direction P = 3.

The address calculation circuit 272 receives the interpolation direction P and calculates the addresses of the RAMs 273 to 276.
The RAM 273 has an original signal on the (y-1) line, a RAM
274 is the original signal on the y line, and RAM275 is (y
Original signal on line +1), (y + 2) in RAM276
The original signals on the line are stored, and the addresses of the four original signals existing in the interpolation direction P are calculated. The four original signals retrieved from the RAMs 273 to 276 by the address calculation circuit 272 are respectively multiplied by the multipliers 277 to 28.
When it is 0, the predetermined coefficient of the filter coefficient memory 281 is multiplied and added by the adder 282 to obtain an interpolation signal.

A concrete operation will be described by using the process of obtaining p3 of the image shown in FIG. Original signals a to g for obtaining p3 are a to g in FIG. 6, and original signals h to n are k to q in FIG.
Matches Slope-3 a and n, slope-2 b and m, slope-1 c and l, slope 0 d and k, slope +1 e and j,
Subtractors 221 to 227 calculate difference values of pairs of original signals of f and i of slope +2 and g and h of slope +3, respectively, and make absolute values by an absolute value circuit 228. The absolute difference value output from the absolute value circuit 228, that is, the correlation value, is 100 for the slopes −3 to 0 and +2 to +3, and 0 for the slope +1 only.

On the other hand, horizontal edge information of the original signals a to g on the y line is calculated by the subtractors 236 to 242,
The original signals a to e and g are 0, and only the original signal f is -100.
Horizontal edge information of the original signals h to n on the (y + 1) line is calculated by the subtracters 243 to 249, and the original signals l to
n, h to j are 0, and only the original signal k is -100.

In the correlation value correction circuits 229 to 235,
The absolute difference value of the edge information in the horizontal direction of the original signal corresponding to the slopes -3 to +3 is calculated. At the slopes -3 to -1, +1, +3, the absolute difference value of the edge information is 0, and the slope 0,
It becomes 100 at +2. The absolute difference value of the horizontal edge information obtained here is added to the correlation value output from the absolute value circuit 228. Inclination -3 to -1, +1, +3
, There is no edge in the horizontal direction in the original signal on the y line and the original signal on the (y + 1) line, so there is no change in the value of the correlation value, but when the slope is 0 or +2, the original signal of either line is Since the signal has edges in the horizontal direction, the absolute difference values of the edge information in the horizontal direction are added, and the slopes 0 and +2 are both 200.

The vertical edge information of the original signals a to g on the y line is calculated by the subtracters 257 to 263, and the original signals a to e become 0 and the original signals f to g become -100. (Y +
1) Vertical edge information of original signals h to n on a line is calculated by subtractors 264 to 270, and original signals m to n,
h to j are 0, and original signals k to l are -100.

In the correlation value correction circuits 250 to 256,
The absolute difference value of the edge information in the vertical direction of the original signal corresponding to the slopes -3 to +3 is obtained. The slopes -3 to -2 and +1 are 0, and the slopes -1 to 0 and +2 to +3 are 100. When the absolute difference value of the edge information in the vertical direction obtained here is added to the correlation values corrected by the correlation value correction circuits 229 to 235, the slopes -3 to -2 are 100, the slopes -1, +3 are 200, and the slopes are -3. 0 and +2 are 300, and inclination +1 is 0.

In the evaluation circuit 271, the correlation value correction circuit 25
Corrected correlation value Dr in 0 to 256 _- When the evaluation of ₃ minimum of ～Dr _3, the correlation value Dr ₁ = 0 slope +1 is evaluated,
1 is output as the interpolation direction P.

In the address calculation circuit 272, the interpolation direction P
= 1, the addresses of four original signals in the direction of inclination +1 with p3 as the center are calculated. The four original signals called from the RAMs 273 to 276 by the address calculation circuit 272 are respectively multipliers 277 to 28.
When it is 0, the predetermined coefficient of the filter coefficient memory 281 is multiplied and added by the adder 282 to obtain an interpolation signal.

As the coefficient of the coefficient memory 281, for example,
If 0 is used for the multiplier 277, 0.5 is used for the multiplier 278, 0.5 is used for the multiplier 279, and 0 is used for the multiplier 280, the original signals existing on the upper and lower two lines in the interpolation direction P are used. The average value is interpolated, and the multiplier 277 has -0.212.
, 0.637 in the multiplier 278 and 0.
When 637 is used and -0.212 is used for the multiplier 280, cubic convolution interpolation is performed in the interpolation direction P. Whichever interpolation coefficient is used, the interpolation signal p3 = 100
Becomes

Similarly, p4 is obtained. Similar to the above, the correlation value of the set of original signals having the slopes of -3 to +3 is obtained. When the difference absolute value of the edge information in the horizontal direction is obtained, all are 0. However, in the slopes -3 to 0 and +2 to +3, there is no edge in the original pixel on the y line and the original pixel on the (y + 1) line, but at the slope +1 both on the y line and on the (y + 1) line, There are similar edges. Therefore, a certain value α1 is subtracted only for the correlation value having the slope of +1. Here, the description will be continued assuming that α1 = 5. Therefore, the correlation value corrected by the edge information in the horizontal direction has a slope of -3 to 0 and +2 to +3 of 10
0 and inclination +1 are -5. Then, subtracters 257-2
The edge information in the vertical direction is obtained at 63, and the absolute value of the difference between the vertical edge information with respect to each inclination is obtained. The inclinations -3 to -1, +1, +3 are 0, and the inclinations 0, +2 are 100.
Becomes When this absolute difference value is added to the correlation value corrected by the edge information in the horizontal direction, the slopes are -3 to -1, +3.
Is 100, the gradient is 0, +2 is 200, and the gradient +1 is -5. The original signal on the y line, (y +
1) Since the original signals on the line have edges and are similar to each other, a certain value α2 is subtracted from the correlation value. Here, as in the case of the correlation value correction based on the horizontal edge information, the description will be continued with α2 = 5. Therefore, the correlation value is −10 only when the slope is +1. When evaluating the minimum value of the correlation values Dr _-3 ~Dr ₃ obtained as described above, the correlation value Dr
₁ becomes the minimum, and the evaluation circuit 271 outputs 1 as the interpolation direction P. The obtained correlation value is used as the edge information of the original signal on the y line in the horizontal and vertical directions (y +
1) Correlation value Dr _-3 when corrected by the absolute value of the difference between the original and horizontal edge information of the original signal on the line
˜Dr ₃ is slope −3 to −1, +3 is 100, slope +1
Becomes −10, and the slope becomes 0 and +2 becomes 200. Therefore, the correlation value Dr ₁ becomes the minimum, and the evaluation circuit 271 outputs 1 as the interpolation direction P. As a result, p4 = 0 from the original signal existing in the direction of inclination +1 with p4 as the center.

Next, the operation of the intra-field interpolation circuit 114 as the second embodiment will be described in detail with reference to FIG.

In the second embodiment, the calculation of the absolute value of the difference between the input signal and the original signal with respect to the interpolation direction and the calculation of the edge information in the vertical direction are the same as those in the first embodiment shown in FIG.

In FIG. 3, the input signal delayed by the 1H memory 111 is the original signal on the y line, and is a 1D delay device (1D corresponds to one pixel in interlaced scanning) 301.
Delayed by ~ 306 to obtain the original signals ag. The original signals a to g correspond to a to g on the original line y shown in FIG.
The input signal delayed by the 1H memory 112 is (y + 1)
The original signal on the line is delayed by the 1D delay devices 307 to 312 to obtain original signals h to n. The original signals h to n correspond to h to n on the original line (y + 1) shown in FIG. By the subtractors 319 to 325, the slopes -3 to + shown in FIG.
The difference value for the set of 3 original signals is obtained. The calculated difference value is converted into an absolute value by the absolute value circuit 326, and is input to the correlation value correction circuits 327 to 333 as the correlation value indicating the correlation.

On the other hand, the edge information in the vertical direction of the original signal on the y line is calculated as a difference value with the adjacent original signal on the (y-1) line located immediately above by using the subtractors 335 to 341. Further, the edge information in the vertical direction of the original signal on the (y + 1) line is also obtained by using the subtracters 342 to 348.
Calculate the difference value. As described above, the correlation value calculated by the absolute value circuit 326 based on the vertical edge information of the original signal on the y line and the vertical edge information of the original signal on the (y + 1) line is used as the correlation value correction circuits 327 to 333. Correct with.

The correction processing contents of the correlation values in the correlation value correction circuits 327 to 333 are the same as the correction means in the vertical edge information of the first embodiment for the slopes -3 to -1 and +1 to +3. .

Correlation value correction circuits 327-329, 331-
Correlation value corrected in 333, that is, slope −3 to −
The correlation values of 1, +1 to +3 are input to the evaluation circuit 349, but the correlation value correction circuit 330 uses the vertical edge information of the set of original pixels with a slope of 0 for the correlation value of a slope of 0. And make corrections.

In the interpolation of diagonal edges, a sufficient interpolation signal can be obtained only with edge information in the vertical direction. However, as shown by the vertical line in FIG. 9, in an image with only horizontal edges, correction of the correlation value based on edge information in the vertical direction alone cannot specify a desired interpolation direction, and an incorrect interpolation direction is selected. Therefore, there is a possibility that the image quality will be significantly deteriorated. When the correction of the correlation value based only on the vertical edge information is applied to the image as shown in FIG. 9, the correlation value after the correction based on the vertical edge information is not included in the interpolated pixel p3 except for the slopes −1 and +1. It becomes 0, and the tilt direction cannot be specified. Inclination -3 to -2, +2
When the interpolation pixel p3 is created by using +3, p3 = 1
00, which is significantly different from the desired value of 0. Also, the slope is -3 to -2, 0. Even when the average value of the original pixels belonging to +2 to +3 is used as the pixel value of the interpolation pixel p3, p3 =
The value is 80, which is also significantly different from the desired value.

Therefore, in the present embodiment, the correlation value correction circuit 330 is determined by the vertical edge information of the set of original pixels having the inclination of 0.
The correlation value corrected by the correlation value correction circuit 33
Correct with 4. The details of the processing will be described below.

In the correlation value correction circuits 327 to 333, when a vertical edge exists and the vertical edge information has high correlation, a certain value α is set to the correlation value calculated by the absolute value circuit 326. A correction process for subtraction is performed. In the correlation value correction circuit 334, when there is no vertical edge in each original pixel of the set of original pixels with a slope of 0 and the vertical edge information has high correlation, the correlation value corrected by the correlation value correction circuit 330 Is subtracted by a certain value β. In the case of limiting to a set of original pixels having a slope of 0, if the vertical edge does not exist and the correlation of the vertical edge information is high, the interpolated pixel is
It is likely that it exists inside an image. For that reason, a certain value β is subtracted only for the correlation value at the slope 0.

In the evaluation circuit 349, the correlation value correction circuit 32
Correlation value has been corrected by the vertical edge information in 7~329 Dr _-3 ~Dr _-1, the correlation value correction circuit correlation value has been corrected by the vertical edge information in 331~333 Dr ₁ ~Dr _3, the correlation value correction circuit 330 and the correlation value correction circuit 334 evaluate the minimum value of Dr ₀ corrected by the vertical edge information,
The optimum interpolation direction P is output.

The address calculation circuit 350 receives the interpolation direction P and calculates the addresses of the RAMs 351 to 354.
The RAM 351 has an original signal on the (y-1) line, a RAM
352 is the original signal on the y line, and RAM 353 is (y
The original signal on the (+1) line, (y + 2) in the RAM 354.
The original signals on the line are stored, and the addresses of the four original signals existing in the interpolation direction P are calculated. The four original signals retrieved from the RAMs 351 to 354 by the address calculation circuit 350 are respectively multiplied by multipliers 355 to 35.
In step 8, the predetermined coefficient in the filter coefficient memory 359 is multiplied, and the result is added in the adder 360 to obtain an interpolation signal.

A concrete operation of the intra-field interpolating circuit of the second embodiment will be described by using the process of obtaining p3 of the image shown in FIG. Original signal a to obtain p3
g corresponds to a to g in FIG. 6, and the original signals h to n correspond to k to q in FIG. Slope-3 a and n, slope-2 b and m, slope-
Subtractors 319 to 325 calculate the difference values of the original signal pairs of c and l of 1, d and k of 0, e and j of +1, f and i of +2, and g and h of +3, respectively. , Absolute value circuit 3
It is converted into an absolute value at 26. The absolute difference value output from the absolute value circuit 326, that is, the correlation value, is 100 when the slope is -3 to 0 and +2 to +3, and is 0 only when the slope is +1.

On the other hand, vertical edge information of the original signals a to g on the y line is calculated by the subtracters 335 to 341,
The original signals a to e are 0, and the original signals f to g are -100.
Vertical edge information of the original signals h to n on the (y + 1) line is calculated by the subtracters 342 to 348, and the original signals h to n are calculated.
j and m to n are 0, and the original signals k to l are -100.

In the correlation value correction circuits 327 to 333,
The absolute difference value of the edge information in the vertical direction of the original signal corresponding to the slopes -3 to +3 is obtained. At slopes -3 to -2, +1, the absolute difference value of the edge information is 0, slopes -1 to 0, +2
It becomes 100 in the range of +3. When the absolute difference value of the vertical edge information obtained here is added to the correlation value output from the absolute value circuit 326, the slopes -3 to -2 are 100,
The slopes −1 to 0, +2 to +3 are 200, and the slope +1 is 0. The correlation value correction circuit 334 pays attention to the vertical direction edge information of the original signal at the inclination of 0, especially the presence or absence of an edge. In the interpolated signal p3 of FIG. 6, since the original signal located immediately above has no edges and the original signal located immediately below has edges, the correlation value is not corrected.

In the evaluation circuit 349, the correlation value correction circuit 32
Correlation value is corrected by _{7~329 Dr - 3 ~Dr -1, Dr} 0 corrected by the correlation value correction circuit 334, the correlation value correction circuit 331
When the minimum value of Dr ₁ to Dr ₃ corrected by ˜333 is evaluated, the correlation value Dr ₁ = 0 of the slope +1 is evaluated, and the interpolation direction P
Is output as 1.

In the address calculation circuit 350, the interpolation direction P
= 1, the addresses of four original signals in the direction of inclination +1 with p3 as the center are calculated. The four original signals read out from the RAMs 351 to 354 by the address calculation circuit 350 are respectively multiplied by multipliers 355 to 35.
In step 8, the predetermined coefficient in the filter coefficient memory 359 is multiplied, and the result is added in the adder 360 to obtain an interpolation signal. The obtained interpolation signal p3 is 3 even in the mean value interpolation.
Even with the next convolutional interpolation, the value is 100.

Similarly, p4 is obtained. Similarly to the above, the correlation value of a pair of original signals having a slope of -3 to +3 is calculated, and the edge information in the vertical direction of the original signal on the y line and the vertical direction of the original signal on the (y + 1) line are calculated with respect to the calculated correlation value. If the absolute value of the difference from the edge information of
It is 100 for -1, +3, 200 for slopes 0 and 2, and 0 for slope +1. For the slope +1, the original signal on the y line and the original signal on the (y + 1) line have edges and are similar to each other.
Subtract 1 (= 5). As a result, if the slope is +1 then -5
Becomes In the correlation value correction circuit 334, y when the slope is 0
There is no vertical edge of the original signal on the line,
Since there is a vertical edge of the original signal on the (y + 1) line, the correlation value is not corrected. Therefore, the correlation values Dr _{-3 to} Dr _-1 , Dr ₃ are 100, and Dr ₀ and Dr ₂ are 20.
0 and Dr ₁ become -5, the correlation value Dr ₁ becomes the minimum, and the evaluation circuit 349 outputs 1 as the interpolation direction P. As a result, p4 = 0 from the original signal existing in the direction of inclination +1 with p4 as the center.

Next, the effect of the correlation value correction circuit 334 will be specifically described by using the process of obtaining p3 of the image shown in FIG. The original signals a to g for obtaining p3 correspond to a to g in FIG. 9, and the original signals h to n correspond to k to q in FIG. Slope-3 a and n, slope-2 b and m, slope-1 c and l, slope 0 d and k, slope +1 e and j, slope +2
F and i, and gradient +3 g and h respectively, the difference value of the pair of original signals is calculated by the subtractors 319 to 325, and the absolute value circuit 326 is calculated.
To absolute value. The absolute difference value output from the absolute value circuit 326, that is, the correlation value, has a slope of −3 to −2, 0, +2.
It is 0 for +3 and 100 for a slope of -1 and +1.

Since neither the original signal on the y line nor the original signal on the (y + 1) line has an edge in the vertical direction,
The absolute value of the vertical edge information difference for the slopes -3 to +3 is 0, and the correlation value correction circuits 327 to 333 do not correct the correlation value. However, the correlation value correction circuit 3
In 34, the original signal on the y line for a slope of 0,
Since there is no edge in the original signal on the (y + 1) line, a certain value β is subtracted. Here, the description will be continued with β = 3. Therefore, the correlation value for the slope 0 is -3. Therefore, the correlation values Dr _{-3 to} Dr _-2 , Dr _{2 to} Dr ₃ are 0, D
r ₋₁ and Dr ₁ are 100, Dr ₀ is −3, and the correlation value Dr _{0 is}
Is minimized, and the evaluation circuit 349 outputs 1 as the interpolation direction P. As a result, the slope around p3 is +1
The average value interpolation or the cubic convolution interpolation is performed using the original signal existing in the direction of, and 0 is obtained as the interpolation signal p4.

As described above, the interpolation signals are sequentially obtained in both the first and second embodiments.

As a result of the above operation, in both the first and second embodiments, the slanted edges and slanted lines generated by the surface,
Furthermore, effective scanning line interpolation can be performed on vertical lines.

Furthermore, although the correlation is evaluated from the difference value of the original signals, it is possible to increase the number of original signals in the same manner.

Even if the correlation value correction circuit is constituted by a look-up table memory, the same effect can be obtained.

[0086]

As described above, according to the present invention, when a video signal of interlaced scanning is converted into a video signal of progressive scanning, a candidate of a set of original pixels for obtaining a difference absolute value of pixel values is interpolated. Selected from a set of original pixels having a point symmetry centered on the pixel, of which, the difference absolute value of the pixel values is calculated, and the calculated difference absolute value is based on the edge information of the original pixel, It is possible to correct and create the interpolated pixel based on the set of original pixels for which the corrected absolute difference value is minimized.

Therefore, effective scanning line interpolation can be performed even for a diagonal edge or a diagonal line generated by a surface.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a progressive scan conversion apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of an intra-field interpolation circuit according to the first embodiment of the present invention.

FIG. 3 is a block diagram of an intra-field interpolation circuit according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram that defines a vertical direction and an oblique direction according to the embodiment of this invention.

FIG. 5 is an explanatory diagram for defining edge information according to the embodiment.

FIG. 6 is an explanatory diagram of a procedure for creating an interpolated pixel for an oblique edge according to the embodiment.

FIG. 7 is an explanatory diagram of a procedure for creating an interpolation pixel for a diagonal line according to the same embodiment.

FIG. 8 is an explanatory diagram of an interpolation pixel creation procedure for another diagonal line according to the embodiment.

FIG. 9 is an explanatory diagram of a procedure for creating an interpolation pixel for a vertical line in the embodiment.

[Description of Reference Signs] 101 original pixel selection circuit 102 correlation value calculation circuit 103 edge information detection circuit 104 correlation value correction circuit 105 slope detection circuit 106 address calculation circuit 107 RAM 108 filter circuit 109 filter coefficient memory 110 to 112 1H memory 113 time axis Conversion circuit 114 In-field interpolation circuit 201-220 1D delay device 221-227, 236-249, 257-270 Subtractor 228 Absolute value circuit 229-235, 250-256 Correlation value correction circuit 271 Evaluation circuit 272 Address calculation circuit 273- 276 RAM 277 to 280 Multiplier 281 Filter coefficient memory 282 Adder 283 Filter circuit 301 to 318 1D delay device 319 to 325, 335 to 348 Subtractor 326 Absolute value circuit 327 to 334 Correlation value correction times 349 evaluation circuit 350 the address calculation circuit 351 to 354 RAM three hundred fifty-five to three hundred fifty-eight multiplier 359 filter coefficient memory 360 Adder 361 filter circuit

Claims (19)

[Claims] 1. When converting a video signal of interlaced scanning into a video signal of progressive scanning, an interpolated pixel for the conversion is determined based on an original pixel obtained by sampling the video signal of one field of the interlaced scanning in a grid pattern. In the progressive scanning conversion method to be created, after selecting a set of original pixels having a point symmetry relationship centered on the interpolation pixel and calculating a correlation value of pixel values of the selected set of original pixels, The correlation value is corrected based on the correlation of the edge information in each original pixel forming a set, and the set of original pixels for creating the interpolation pixel is selected based on the corrected correlation value. Progressive scan conversion method. 2. The progressive scan conversion method according to claim 1, wherein the correlation value of the pixel values of the set of original pixels sandwiching the interpolation pixel is the absolute difference value of the pixel values of the set of original pixels. 3. The progressive scan conversion method according to claim 1, wherein the edge information of the original pixel is a difference value between the pixel and an adjacent pixel in the vertical direction. 4. The progressive scan conversion method according to claim 1, wherein the edge information of the original pixel is a difference value between pixels adjacent in the horizontal direction. 5. The progressive scan conversion method according to claim 1, wherein the correlation of the edge information is calculated by a difference absolute value of the edge information. 6. When it is not possible to specify only one interpolation direction for a set of original pixels having the highest correlation according to the correlation value of pixel values, the original pixels existing in some candidate interpolation directions are used. The progressive scan conversion method according to claim 1, wherein the interpolation pixel is created. 7. The progressive scan conversion method according to claim 1, wherein the pixel value of the interpolation pixel to be created is an average value of pixel values of a set of original pixels having a minimum difference absolute value of pixel values. 8. The progressive scan conversion method according to claim 1, wherein the interpolation pixel is created based on original pixels in an interpolation direction on a plurality of upper and lower lines sandwiching the interpolation pixel. 9. When converting a video signal of interlaced scanning into a video signal of progressive scanning, an interpolated pixel for the conversion is calculated based on an original pixel obtained by sampling the video signal of one field of the interlaced scanning in a grid pattern. In a progressive scan conversion device to be created, an original pixel selection means for selecting a set of original pixels having a point symmetry relationship with the interpolation pixel to be created, and a pixel value of the original pixel set selected by the original pixel selection means. Correlation value calculation means for calculating the correlation value of the original pixel, edge information detection means for detecting edge information in each original pixel of the set of original pixels, and edge information detected by the edge information detection means Correlation value correction means for correcting the correlation value calculated by the value calculation means, and the original pixel with the highest correlation among the corrected correlation values obtained from the correlation value correction means An inclination detection unit that detects an inclination direction of a set and a filter unit that creates an interpolation pixel for the conversion are provided, and based on a predetermined number of original pixels in the inclination direction detected by the inclination detection unit, A progressive scan conversion device configured to generate interpolation pixels for the conversion by a filter means. 10. The progressive scan conversion apparatus according to claim 9, wherein the correlation value correction means is constituted by a look-up table memory. 11. The inclination detecting means evaluates the correlation with respect to the set of original pixels based on the absolute difference value of the pixel values of the set of original pixels sandwiching the interpolation pixel, and the absolute difference value is minimized. 10. The progressive scan conversion apparatus according to claim 9, wherein the set of original pixels is configured to be evaluated as a set of original pixels having the highest correlation. 12. The filter means according to claim 9, wherein the average value of the pixel values of the set of original pixels having the smallest absolute difference between pixel values is used as the pixel value of the interpolation pixel. Progressive scan conversion device. 13. The progressive scan conversion apparatus according to claim 9, wherein the filter means is configured to create an interpolation pixel based on original pixels in an interpolation direction on a plurality of upper and lower lines sandwiching the interpolation pixel. 14. When converting a video signal of interlaced scanning into a video signal of progressive scanning, an interpolation pixel for the conversion is determined based on an original pixel obtained by sampling the video signal of one field of the interlaced scanning in a grid pattern. In a progressive scan conversion device to be created, an original pixel selection means for selecting a set of original pixels having a point symmetry relationship with the interpolation pixel to be created, and a pixel value of the original pixel set selected by the original pixel selection means. Correlation value calculating means for calculating the correlation value of,
The correlation value calculating means using the vertical edge information detecting means for detecting vertical edge information in each original pixel of the set of original pixels and the vertical edge information detected by the vertical edge information detecting means. And a vertical direction detected by the vertical direction edge information detecting means in each original pixel of a set of original pixels located above and below the interpolated pixel. Second correlation value correction means for correcting the correlation value of the set of the original pixels obtained by the first correlation value correction means, the first correlation value correction means, and the second edge information Of the corrected correlation values obtained from the correlation value correction means, a tilt detection means for detecting the tilt direction of the set of original pixels having the highest correlation, and a filter means for creating an interpolated pixel for the conversion are provided. , The inclination Based on a predetermined number of original pixels in the selected interpolation direction detection means, by the filter means, interlacing device configured to create an interpolation pixel for the conversion. 15. The first correlation value correcting means is constituted by a look-up table memory.
The progressive scan conversion device described. 16. The second correlation value correcting means is constituted by a look-up table memory.
The progressive scan conversion device described. 17. The inclination detecting means evaluates the correlation with respect to the set of original pixels based on the absolute difference value of the pixel values of the set of original pixels sandwiching the interpolation pixel, and the absolute difference value is minimized. 15. The progressive scan conversion apparatus according to claim 14, wherein the set of original pixels is configured to be evaluated as a set of original pixels having the highest correlation. 18. The filter means according to claim 14, wherein an average value of pixel values of a set of original pixels having a minimum absolute difference between pixel values is used as a pixel value of an interpolated pixel. Progressive scan conversion device. 19. The filter means is configured to create an interpolation pixel based on original pixels in an interpolation direction on a plurality of upper and lower lines sandwiching the interpolation pixel.
The progressive scan conversion device described.