KR100437100B1 - Method and circuit for converting interlaced scanning signal to progressive scanning signal - Google Patents

Abstract

An interlaced / sequential scan conversion circuit and method for determining the value of an interpolated pixel using pixel values of peripheral pixels in a selected image field are disclosed. The interlaced / sequential scan conversion circuit and method of the present invention comprises a first one-dimensional pixel line and a second one-dimensional pixel line respectively positioned above and below the line with the pixel S (i, j) to be interpolated in the selected image field. The first direction correlation P (k) and the second direction correlation Q (k) are calculated from the extracted pixels. Interpolation direction is determined by comparing the sizes of P (k) and Q (k), and the pixel value of the pixel to be interpolated is obtained by using the pixel values of the peripheral pixels corresponding to the determined interpolation direction, and the obtained pixel value Is generated as a pixel value of the interpolated pixel. The progressive scan image signal generated by the interlaced / sequential scan conversion method and the conversion circuit of the present invention increases accuracy in grasping the direction of the interpolated pixels, even when the interpolated pixels are not perpendicular or 45 °. Has an image that approximates the image for the original target object. In particular, according to the interlaced / sequential scan conversion method and conversion circuit of the present invention, it is easy to obtain a high quality still image desired by a user after storing a certain amount of an analog TV signal into a capture card.

Description

TECHNICAL AND CIRCUIT FOR CONVERTING INTERLACED SCANNING SIGNAL TO PROGRESSIVE SCANNING SIGNAL}

The present invention relates to a method and circuit for converting an interlaced video signal into a progressive scan video signal. In particular, an interlaced / sequential scan conversion for determining an interpolated pixel value using pixel values of peripheral pixels in a selected image field It relates to a circuit and a method.

In general, a method of scanning a video signal in a television monitor or the like includes an interlaced scanning method for scanning while skipping line by line and a progressive scanning method for scanning every line. As is well known, NTSC color television systems employ interlaced scanning to mitigate the requirements of the transmission band. The interlaced scanning method scans half of one frame (herein referred to as "field") during a time corresponding to 1/2 of a frame period. That is, according to the interlaced scanning method shown in FIG. 1, the image signal is scanned only in odd-numbered pixel lines in the odd image field and only in even-numbered pixel lines in the even image field. However, the image of the image signal by the interlaced scanning method has the disadvantage that it becomes visually unnatural due to the edge flicker, shimmering, the jagged shape. In order to solve this disadvantage, it is proposed to convert an interlaced video signal into a progressive scan video signal. In order to convert the interlaced video signal into a progressive scan video signal, the pixel values of pixels existing in the non-scanned line in the interlaced video signal must be interpolated. Currently, various interpolation methods have been proposed as interpolation methods for determining pixel values of interpolated pixels. One of such interpolation methods is an ELA interpolation method using an edge based line average (ELA) algorithm. The ELA interpolation method is a method of interpolating by finding the direction of the interpolated pixel. The ELA interpolation method is a pixel value difference between pixels in a diagonal direction and a pixel value difference between pixels in a vertical direction based on a pixel to be interpolated, and is an average value of pixel values of two pixels having a minimum value difference. The pixel value of the interpolated pixel is determined.

However, the interpolation by the ELA interpolation method has a problem in that the accuracy of grasping the directionality is low when the interpolation pixel is not perpendicular or 45 °. Therefore, in the existing interlaced / sequential scan conversion circuit and method, there is a problem that the image of the target object by the progressive scan video signal converted from the interlaced video signal is significantly different from the image of the original target object.

Accordingly, it is an object of the present invention to improve the accuracy of grasping the orientation of the interpolated pixels so that the image approaching the image of the original object is displayed even when the interpolation of the pixels is not perpendicular or 45 °. An interlaced / sequential scan conversion circuit and method are provided.

In order to more fully understand the drawings used in the detailed description of the invention, a brief description of each drawing is provided.

1 is a view for explaining an interlaced scanning method.

2 is a flowchart illustrating a method for interlaced / sequential scan conversion according to an embodiment of the present invention.

3 is a diagram for explaining first and second directional correlations of interpolation pixels.

4 to 6 are diagrams for describing a method of determining a peripheral pixel having a minimum pixel value difference.

7 is a block diagram schematically illustrating an interlaced / sequential scan conversion circuit according to an embodiment of the present invention.

One aspect of the present invention for achieving the above technical problem relates to an interlaced / sequential scan conversion method for converting an interlaced video image signal to a progressive scan video signal. The interlaced / sequential scan conversion method of the present invention comprises the steps of: (A) receiving the interlaced video signal; (B) selecting a predetermined image field from the received interlaced video signal; (C) extracting from the selected image field a first one-dimensional pixel line and a second one-dimensional pixel line respectively positioned above and below the line with the pixel S (i, j) to be interpolated; (D) S (ik, jm) and S (ik, j-m + n) (where m is an integer and k and n are natural numbers) from the first one-dimensional pixel line, and the second one-dimensional pixel The first directional correlation P (k) for the pixel S (i, j) to be interpolated by obtaining the values of S (i + k, j-m + n) and S (i + k, jm) from the line, respectively And calculating a second direction correlation Q (k), wherein P (k) is Σ _m | S (ik, jm) -S (i + k, j-m + n) | k) is calculated as:? _m | S (ik, j-m + n) -S (i + k, jm) | (E) determining the interpolation direction by comparing the magnitudes of the first direction correlation P (k) and the second direction correlation Q (k); And (F) obtaining pixel values of pixels to be interpolated using pixel values of peripheral pixels corresponding to the interpolation direction determined in step (E), and sequentially obtaining the obtained pixel values as pixel values of the interpolated pixels. Generating a scanning video signal. K is a natural number different from n / 2.

One aspect of the present invention for achieving the above technical problem relates to an interlaced / sequential scan conversion circuit for converting an interlaced video signal to a progressive scan video signal. An interlaced / sequential scan conversion circuit of the present invention comprises: receiving means for receiving the interlaced video signal; Field selection means for selecting a predetermined image field from the received interlaced video signal; In the selected image field, S (ik, jm) and S (ik, j-m + n), where m is an integer, from a first one-dimensional pixel line respectively positioned above and below the line with the pixel to be interpolated. Peripheral pixels extracting means for extracting values of S (i + k, j-m + n) and S (i + k, jm) from the second one-dimensional pixel line; A first direction correlation P (k) and a second direction correlation Q (k) are calculated for the pixel S (i, j) to be interpolated, and the first direction correlation P (k) and the second direction are calculated. As directional determination means for determining interpolation direction by comparing the magnitude of correlation Q (k), P (k) is Σ _m | S (ik, jm) -S (i + k, j-m + n) Wherein the Q (k) is? _M | S (ik, j-m + n) -S (i + k, jm) | Interpolation means for determining a pixel value of a pixel to be interpolated using the pixel value of a peripheral pixel corresponding to the determined interpolation direction, and determining the obtained pixel value as a pixel value of the pixel to be interpolated; And generating means for generating a sequential scan image signal with the pixel values of the interpolated pixels determined by the interpolation means. K is a natural number different from n / 2.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. For each figure, like reference numerals denote like elements.

2 is a flowchart illustrating a method for interlaced / sequential scan conversion according to an embodiment of the present invention. 2, the interlaced / sequential scan conversion method of the present invention is described. First, an interlaced video signal (ITIMG) generated by interlaced scanning is received (S210). A radix image field or even image field in which only half of one frame is scanned is selected from the received interlaced video signal ITIMG (S220). In the odd image field, pixels on odd lines have pixel values, and pixels on even lines do not have pixel values. In the even image field, pixels on even lines have pixel values, but pixels on odd lines do not have pixel values.

Subsequently, in the selected imagefield, steps for interpolating the unscanned pixels are described. First, a pixel to be interpolated (hereinafter referred to as 'interpolation pixel') is determined, and pixel values of pixels (hereinafter referred to as 'main change pixel') located around the interpolation pixel are extracted (S230). If the selected image field is the even image field, the interpolation pixel S (i, j) is selected in the odd pixel lines. In the even-numbered pixel line, predetermined pixels (for example, S (i-1, j-1), S (i-1, j), S (i-1, j + 1), S (i + 1, j-1), S (i + 1, j), S (i + 1, j + 1, etc.) are extracted to the peripheral pixels. Further, pixel values of the peripheral pixels (eg, V (i-1, j-1), V (i-1, j), V (i-1, j + 1), V (i + 1, j-1), V (i + 1, j), V (i + 1, j + 1, etc.) are also extracted (S230). In the present specification, for convenience of description, pixels of a frame or image field are represented by S (i, j) or the like, and pixel values of each pixel are represented by V (i, j). Therefore, V (i, j) represents the pixel value of the pixel S (i, j).

Subsequently, the first direction correlation P (k) and the second direction correlation Q (k) of the interpolation pixel are obtained using the extracted pixel values of the peripheral pixels (S242). The first directional correlation P (k) and the second directional correlation Q (k) express numerically the advancing direction of the image of the interpolation pixel, and are generally represented by the following equations (1) and (2). Same as

P (k) = ∑ _m ｜ S (ik, jm) -S (i + k, j-m + n) | --- Equation (1),

Q (k) = ∑ _m | S (ik, j-m + n) -S (i + k, jm) | --- Equation (2).

Accordingly, the first directional correlation P (k) and the second directional correlation Q (k) represent correlations in directions that are symmetric with each other. Here, k represents the difference between the line where the interpolation pixel is disposed and the line where the selected peripheral pixel exists. That is, when k is 1, it indicates that the neighboring pixel exists directly above or below the interpolation pixel. M is an integer of 0 ≦ m ≦ k, wherein P (k) and Q (k) are sigma for m. Therefore, P (k) and Q (k) are implemented as the sum of a plurality of pixel difference values. N is an element that determines the direction of two peripheral pixels to be compared. By setting n differently, it is possible to compare two pixel values at various angles. Preferably, said n is 1 and it is an integer of 0 <= m <= k.

FIG. 3 is a diagram for explaining the first direction correlation P (k) and the second direction correlation Q (k), where k is 1. FIG. As shown in FIG. 3, the first direction correlation P (1) and the second direction correlation Q (1) of the interpolation pixel S (i, j) are represented by Equation (3) and Equation ( Same as 4).

P (1) = | S (i-1, j) -S (i + 1, j + 1) | + | S (i-1, j-1) -S (i + 1, j) |- -(3)

Q (1) = | S (i-1, j + 1) -S (i + 1, j) | + | S (i-1, j) -S (i + 1, j-1) |- -(4)

Referring back to FIG. 2, in the interlaced / sequential scan conversion method of the present invention, the magnitudes of the first direction correlation P (k) and the second direction correlation Q (k) are subsequently compared (S245). ). That is, in step S245, the interpolation direction of the interpolation pixel may be determined. That is, in step S245, the interpolation direction that preliminarily shows the change direction of the pixel value of the interpolation pixel by comparing the first direction correlation P (k) with the second direction correlation Q (k). Can be identified. For example, the interpolation direction in the case of P (1)> Q (1) includes peripheral pixels forming Q (1), that is, pixels S (i-1, j + 1) and pixels S (i + 1). , j) or the direction in which the pixel S (i-1, j) and the pixel S (i + 1, j-1) are connected. Similarly, the interpolation direction in the case of P (1) < Q (1) includes peripheral pixels forming P (1), that is, pixels S (i-1, j-1) and pixels S (i + 1, j ) Or the direction of connecting the pixel S (i-1, j) and the pixel S (i + 1, j + 1). When P (1) = Q (1), the interpolation direction is both the direction connecting P (1) and the peripheral pixels forming Q (1).

The pixel difference between two pixels in the symmetric direction corresponding to the interpolation direction determined in step S245 is compared with the pixel value difference between two pixels in the vertical direction, and two pixels having a minimum pixel value difference are extracted ( S250). In reference numeral S250 of FIG. 2, the case where k is 1 is shown as a representative example. Each case is specifically described as follows.

First, the case where P (1)> Q (1) is described. Two peripheral pixels in the symmetry direction corresponding to the interpolation direction in the case of P (1)> Q (1) are pixels S (i-1, j + 1) and pixels S (i + 1, j-1). Therefore, in the case of P (1)> Q (1), two pixels S (i-1, j) and S (i + 1,2) in the vertical direction with respect to the interpolation pixel S (i, j). the pixel value difference C (0) of the j) and two pixels S (i-1, j + 1) and S (i + 1, j-1) in the symmetry direction corresponding to the interpolation direction. By comparing the value difference C (-1), two peripheral pixels having the minimum pixel value difference are extracted (S250a) (see Fig. 4). Here, C (t) may be obtained by Equation (5), and represents a pixel value difference between two pixels in a symmetrical or vertical direction.

C (t) = | S (i-1, j-t) -S (i + 1, j + t) | --- (5)

If C (0)? C (-1), the two peripheral pixels having the smallest pixel value difference are pixels S (i-1, j) and pixels S (i + 1, j). If C (0)> C (-1), the two peripheral pixels having the smallest pixel value difference are pixels S (i-1, j + 1) and pixels S (i + 1, j-1).

Next, the case where P (1) = Q (1) is described. Two peripheral pixels in the symmetry direction corresponding to the interpolation direction when P (1) = Q (1) are a pair of pixel S (i-1, j + 1) and pixel S (i + 1, j-1). And a pair of pixels S (i-1, j-1) and pixels S (i + 1, j + 1). Therefore, when P (1) = Q (1), pixel value differences C (0), C (of pixel two in the vertical direction and two symmetry directions with respect to the interpolation pixel S (i, j). -1), C (1) is compared, and two peripheral pixels having a minimum pixel value difference are extracted (S250b) (see Fig. 5).

In addition, two peripheral pixels in the symmetry direction corresponding to the interpolation direction in the case of P (1) < Q (1) are pixels S (i-1, j-1) and pixels S (i + 1, j + 1). to be. Therefore, when P (1) < Q (1), two peripheral pixels having a minimum pixel value difference are extracted by comparing C (0) and C (1) (S250c) (see Fig. 6).

Subsequently, in step S250, the weighted average value of the pixel values of the peripheral pixels that are weighted with respect to the pixel values of the two peripheral pixels to be extracted is obtained, and the pixel values of the interpolated pixels are determined by the obtained weighted average values (S257). ). For example, if the comparison result in step S250a is C (0) ≤C (-1), the pixel value V (i, j) of the interpolated pixel S (i, j) is expressed by Equation (6). Same as

V (i, j) = | V (i-1, j) -V (i + 1, j) | / 2 --- (6)

If C (0)> C (1), the interpolated pixel value (V (i, j)) is equal to equation (7). That is, the weight is given to two pixels which influence the directionality, and the pixel value V (i, j) to be interpolated is determined.

V (i, j) = (| 3 * S (i-1, j + 1) + S (i + 1, j + 1) + S (i + 1, j) + 3 * S (i + 1, j-1) ｜) / 8 --- (7)

In addition, the pixel values of the interpolated pixels are determined in the same manner with respect to the comparison results of steps S250b and S250c.

Subsequently, pixels having pixel values interpolated by the interpolation method are combined with pixels having pixel values by the original interlaced scan, thereby generating a progressive scan image signal PRIMG (S260).

According to the interlaced / sequential scan conversion method of the present invention, the directionality with respect to the interpolated pixels can be extracted in an arbitrary direction. In addition, according to the interlaced / sequential scan conversion method of the present invention, while considering many pixel values of the interpolated pixels, the pixel values of the interpolated pixels are weighted with respect to peripheral pixels corresponding to the interpolation direction, and thus interpolated more accurately. The pixel value of the pixel to be extracted can be extracted.

Therefore, according to the interlaced / sequential scan conversion method of the present invention, the accuracy of grasping the direction of the interpolated pixels is increased, and even when the interpolated pixel is not perpendicular or 45 °, the image of the original target object is An image that is close to may be displayed.

As described above, the interlaced / sequential scan conversion method of the present invention may be implemented by the interlaced / sequential scan conversion circuit shown in FIG. 7. Referring to FIG. 7, the interlaced / sequential scan conversion circuit of the present invention includes an image signal receiver 710, a field selector 720, a peripheral pixel extractor 730, directional determination means 740, interpolation means 750, and an image. And a signal generator 760.

The image signal receiver 710 receives an interlaced scanning image signal (ITIMG) scanned in an interlaced scanning manner. The field selector 720 selects an odd image field or an even image field from the received interlaced video signal ITIMG. The peripheral pixel extractor 730 extracts a peripheral pixel of a pixel to be interpolated from the selected odd image field or even image field.

The direction determining means 740 determines the interpolation direction of the pixels to be interpolated using the extracted peripheral pixels. The direction determining means 740 specifically includes a first correlation calculator 741, a second correlation calculator 743, and a directional comparator 745. The first correlation calculator 741 calculates the aforementioned first direction correlation P (k) using the extracted peripheral pixels. The second correlation calculator 743 calculates the aforementioned second direction correlation Q (k). The directional comparator 745 compares the first direction correlation P (k) and the second direction correlation Q (k) to extract interpolation directions of the interpolated pixels.

The interpolation means 750 obtains a weighted average value of peripheral pixels by weighting pixel values of peripheral pixels corresponding to the interpolation direction extracted by the directional determination means 740, and interpolates the obtained weighted average value. Interpolate the pixels. Specifically, the interpolation means 750 includes a pixel difference value extractor 751, a minimum difference value determiner 753, a weighted average value extractor 755, and an interpolation pixel value determiner 757. The pixel difference value extractor 751 obtains the pixel difference value C (t) of the peripheral pixels in the vertical direction and the peripheral pixels in the symmetry direction corresponding to the interpolation direction with respect to the pixels to be interpolated. The minimum difference value determiner 753 compares pixel difference values of the peripheral pixels, for example, C (0) and C (1), and searches for peripheral pixels having a minimum pixel difference value. The weighted average value extractor 755 weights a pixel value of a neighboring pixel having the minimum pixel difference value retrieved by the minimum difference value determiner 753, and weights the weighted average value of the pixel values of the interpolated pixels. Obtain The interpolation pixel value determiner 757 determines the pixel value of the pixel to be interpolated by the weighted average value.

The image signal generator 760 combines the pixels of the pixel line selected by the field selector 720 and the pixels of the line interpolated by the interpolation means 750 to generate a progressive scan image signal PRIMG. . For example, when the even image field is selected, pixels arranged in even lines are determined as original pixel values selected by the field selector 720, and pixels arranged in odd lines are interpolated. The pixel value interpolated by 750 is determined.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

According to the interlaced / sequential scan conversion method and the conversion circuit of the present invention as described above, according to the interlaced / sequential scan conversion method of the present invention, the directionality with respect to the interpolated pixels can be extracted in an arbitrary direction. In addition, according to the interlaced / sequential scan conversion method and the conversion circuit of the present invention, while considering many pixel values of interpolated pixels, the pixel values of the interpolated pixels are weighted with respect to peripheral pixels corresponding to the interpolation direction, The pixel value of the pixel to be interpolated more accurately can be extracted. Accordingly, when the progressive scan image signal generated by the interlaced / sequential scan conversion method and the conversion circuit of the present invention increases accuracy in grasping the direction of the interpolated pixel, and the direction of the interpolated pixel is not vertical or 45 ° Even, it has an image that approximates the image for the original target object.

In particular, according to the interlaced / sequential scan conversion method and the conversion circuit of the present invention as described above, it is easy to obtain a high-quality still image desired by the user after storing a certain amount of the analog TV signal to the capture card.

Claims (8)

In the interlaced / sequential scan conversion method of converting an interlaced video signal into a progressive scan video signal, (A) receiving the interlaced video signal; (B) selecting a predetermined image field from the received interlaced video signal; (C) extracting from the selected image field a first one-dimensional pixel line and a second one-dimensional pixel line respectively positioned above and below the line with the pixel S (i, j) to be interpolated; (D) S (ik, jm) and S (ik, j-m + n) (where m is an integer and k and n are natural numbers) from the first one-dimensional pixel line, and the second one-dimensional pixel The first directional correlation P (k) for the pixel S (i, j) to be interpolated by obtaining the values of S (i + k, j-m + n) and S (i + k, jm) from the line, respectively And calculating a second direction correlation Q (k), wherein P (k) is Σ _m | S (ik, jm) -S (i + k, j-m + n) | k) is calculated as:? _m | S (ik, j-m + n) -S (i + k, jm) | (E) determining the interpolation direction by comparing the magnitudes of the first direction correlation P (k) and the second direction correlation Q (k); And (F) The pixel value of the pixel to be interpolated is obtained by using the pixel values of the peripheral pixels corresponding to the interpolation direction determined in the step (E), and the progressively scanning is performed by using the obtained pixel value as the pixel value of the interpolated pixel. Generating a video signal, K is a natural number different from n / 2. The pixel value of the pixel to be interpolated in the step (F) is Interlaced / sequential scan conversion method, characterized in that the weighted average value of the peripheral pixels weighted to the pixel value of the peripheral pixels corresponding to the interpolation direction. The method of claim 1 or 2, wherein the interpolation direction On the basis of the pixel to be interpolated, a minimum difference value between a pixel value difference between two pixels symmetrically in the diagonal direction of the side having the smaller value among P (k) and Q (k) and a pixel value difference between two pixel values in the vertical direction is determined. Interlaced / sequential scan conversion method characterized in that the branch is determined in the direction of two pixels. delete In an interlaced / sequential scan conversion circuit for converting an interlaced video signal into a progressive scan video signal, Receiving means for receiving the interlaced video signal; Field selection means for selecting a predetermined image field from the received interlaced video signal; In the selected image field, S (ik, jm) and S (ik, j-m + n), where m is an integer, from a first one-dimensional pixel line respectively positioned above and below the line with the pixel to be interpolated. Peripheral pixels extracting means for extracting values of S (i + k, j-m + n) and S (i + k, jm) from the second one-dimensional pixel line; A first direction correlation P (k) and a second direction correlation Q (k) are calculated for the pixel S (i, j) to be interpolated, and the first direction correlation P (k) and the second direction are calculated. As directional determination means for determining interpolation direction by comparing the magnitude of correlation Q (k), P (k) is Σ _m | S (ik, jm) -S (i + k, j-m + n) Wherein the Q (k) is? _M | S (ik, j-m + n) -S (i + k, jm) | Interpolation means for determining a pixel value of a pixel to be interpolated using the pixel value of a peripheral pixel corresponding to the determined interpolation direction, and determining the obtained pixel value as a pixel value of the pixel to be interpolated; And Generating means for generating a sequential scanning video signal as a pixel value of the interpolated pixel determined by the interpolation means, K is a natural number different from n / 2. 6. The pixel value of a pixel to be interpolated in said interpolation means is An interlaced / sequential scan conversion circuit, characterized in that the weighted average value of the neighboring pixels to be weighted with respect to the pixel value of the peripheral pixels corresponding to the interpolation direction. 7. The method of claim 5 or 6, wherein the interpolation direction On the basis of the pixel to be interpolated, a minimum difference value between a pixel value difference between two pixels symmetrically in the diagonal direction of the side having the smaller value among P (k) and Q (k) and a pixel value difference between two pixel values in the vertical direction is determined. The interlaced / sequential scan conversion circuit is characterized in that the branch is determined in the direction of two pixels. delete