JP2009077029A - Signal converter and signal conversion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a signal converter capable of obtaining a smooth interpolation image while suppressing a circuit size and power consumption, and to provide a signal conversion method for the signal converter. <P>SOLUTION: A signal converter has: a line memory 2a for storing pixel data on a first scanning line; a line memory 2b for storing pixel data on a second scanning line of one horizontal synchronization period before; a means 4 for detecting the difference between lines for determining whether the differential value of the pixel data positioned in the same row on both the scanning lines is not less than a first threshold; means 5a, 5b for detecting difference within lines for determining whether the differential value of adjacent pixel data is not less than a second threshold for each of the first and second scanning lines; an interpolation processing determination means 6 for determining an interpolation method for each pixel, based on a result determined by the means 4 for detecting the difference between lines and the means 5a, 5b for detecting difference within lines; and an interpolation pixel data generation means 7 for reading the pixel data stored in the line memories 2a, 2b and for generating interpolation pixel data based on the interpolation method determined by the interpolation processing determination means 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a signal conversion device and a signal conversion method, and more particularly to a signal conversion device and a signal conversion method for converting a video signal of an interlace scanning signal system into a video signal of a progressive scanning signal system.

  Conventionally, as an image data scanning method, there are an interlaced scanning (interlaced scanning) method and a progressive scanning (sequential scanning) method.

  The interlaced scanning method is a scanning method in which image data scanning is alternately repeated for a field in which scanning is performed on odd lines and a field in which scanning is performed on even lines. On the other hand, the progressive scanning method is a scanning method in which image data is scanned in all scanning lines without skipping scanning lines. Therefore, in the interlace scanning method, since one frame display is performed every other line, flicker noise is likely to occur. However, the number of lines scanned in one field is ½ compared to the progressive scanning method. Therefore, since there is an advantage that the horizontal synchronization frequency can be kept low, this interlace scanning method has been often adopted in televisions and the like.

  However, in recent years, some high-resolution displays adopt a progressive scanning method instead of a flickering interlace scanning method. In order to display image information based on the NTSC (National Television System Committee) system, which is one of color television signal systems that are interlace signals, on such a display, conversion from an interlace scan signal to a progressive scan signal is performed. (Hereinafter abbreviated as “I / P conversion” where appropriate).

  Conventionally, as an example of a signal conversion method for performing such I / P conversion, pixel data for two fields composed of interlaced scanning signals is written in a field memory, and a correlation between two consecutive fields is used. There is a method of performing interpolation between odd lines and even lines (hereinafter referred to as “conventional method 1”).

  Specifically, for example, the odd-numbered field and even-numbered field pixel data are written in separate field memories, respectively expanded to twice the number of lines, and the pixel data of each line is added by ½. A method for generating even-line interpolation data is disclosed in Patent Document 1 below.

  As another example of a signal conversion method for performing I / P conversion, pixel data for two lines in the same field composed of interlaced scanning signals is written in a line memory, and the correlation between the two lines is used. Then, there is a method of generating interpolated pixel data from odd lines to even lines and interpolated pixel data from odd lines to odd lines.

  Specifically, for example, based on the pixel data of the first scanning line written in the line memory and the pixel data of the second scanning line before the one horizontal synchronization period, the interpolated pixel data between the two lines is converted to the pixel data of the first scanning line. A method (hereinafter referred to as “conventional method 2”) that is an average value of pixel data of the first scanning line and the second scanning line in the vertical direction, and a point symmetry that is centered on interpolated pixel data between two lines. A method of selecting a combination that minimizes the weighted difference value of the pixel data of the first scanning line and the second scanning line, and using the average value of the pixel data of the first scanning line and the second scanning line as interpolation pixel data (hereinafter, referred to as “interpolated pixel data”). "Conventional method 3"). The following Patent Document 2 discloses a signal conversion method based on the conventional method 3.

  FIG. 6 is a schematic diagram of a conversion method when image conversion is performed based on the conventional method 2 described above.

  As shown in FIG. 6, the interpolated pixel data 53x (x = a, b, c, d, e: the same applies hereinafter) is the average of the pixel data 51x of the first scanning line and the pixel data 52x of the second scanning line. Generated by value. For example, the interpolation pixel data 53a is calculated as (pixel data 51a + pixel data 52a) / 2.

  FIG. 7 is a schematic diagram of a conversion method when image conversion is performed based on the conventional method 3 described above.

  Specifically, on the upper and lower scanning lines sandwiching the interpolation pixel data 63c, a combination of pixel data having a point-symmetric positional relationship with respect to the interpolation pixel data 63 is selected (pixels 62a and 61e, 62b and 61d,.・ ・）, And calculate the difference between these. For convenience of explanation, the combination of pixel data for which a difference value is calculated is a group of five pixel data close to the interpolation pixel data.

  Next, a predetermined threshold value is added to the difference value calculated for each combination. This threshold has a weight in advance so that the value increases as the combination of pixel data farther from the pixel column of the interpolation pixel data becomes larger, and the value becomes smaller as the combination of pixel data closer to the pixel column of the interpolation pixel data. It is determined by the state. That is, in FIG. 7, the threshold value is set to be the largest in the combination of the pixel data 62a and 61e and the combination of the pixel data 62e and 61a, and conversely, the threshold value in the combination of the pixel data 62c and 61c is set to be the smallest. .

  In this way, a combination of pixel data indicating the minimum value is selected from the difference values to which the threshold value has been added, and the value of the interpolated pixel data 63c is determined based on the average value of the selected pixel data.

JP 2004-147285 A JP 2006-148827 A

  According to each of the conventional methods 1 to 3 described above, conversion from an interlaced scanning signal to a progressive scanning signal can be performed.

  However, in the case of the conventional method 1, a plurality of field memories are required, and there is a problem that the circuit scale and power consumption increase.

  In the case of the conventional method 2, the interpolation pixel data is simply calculated by calculating the average value of the pixel data of the first scanning line and the second scanning line in the vertical direction. There is a problem in that a smooth interpolated image cannot be obtained in an image having.

  Furthermore, in the case of the conventional method 3, there is a possibility of erroneous determination depending on the threshold value set in a state having weights in advance, which is obtained based on the interpolation pixel data obtained at this time. When the image is displayed on the screen by the progressive scanning signal, noise may be generated on the screen.

  In view of the above problems, an object of the present invention is to provide a signal conversion device and a signal conversion method thereof that can obtain a smooth interpolation image while suppressing circuit scale and power consumption.

  In order to achieve the above object, a signal conversion apparatus according to the present invention is a signal conversion apparatus that generates interpolated pixel data from an interlaced scanning signal video signal by scanning line interpolation and converts it to a progressive scanning signal video signal. A first line memory for storing pixel data on the first scan line, a second line memory for storing pixel data on the second scan line before one horizontal synchronization period of the first scan line, and the first scan. An inter-line difference detecting means for determining whether or not a difference value of pixel data located in the same column on the line and on the second scanning line is equal to or greater than a first threshold, and in the first scanning line and in the second scanning line For each, based on the determination results of the in-line difference detection means for determining whether or not the difference value of the adjacent pixel data is greater than or equal to the second threshold, the inter-line difference detection means and the in-line difference detection means. And interpolating process determining means for determining an interpolating method for each pixel, and reading out pixel data stored in the first line memory and the second line memory, and based on the interpolating method determined by the interpolating process determining means Interpolated pixel data generating means for generating interpolated pixel data, and the interpolating process determining means determines the interline difference detecting means at the same column position as the target interpolated pixel on the interpolation line to be interpolated. If the result is equal to or greater than the first threshold value, the difference value of the pixel data of adjacent pixels adjacent to the pixel at the same column position either before or after based on the determination result of the in-line difference detection means is equal to or greater than the second threshold value. The scanning line indicating the scan line is searched from the first and second scanning lines, and when the scanning line is searched, the scanning line is specified as the first specific scanning line. Furthermore, on the second specific scanning line which is the other scanning line, a pixel in which the determination result of the in-line difference detection means shows the second threshold value or more from the same column position in the scanning direction is specified as the specific pixel. In the interpolation line, an interpolation method is determined so that a difference value of pixel data between an adjacent pixel and an adjacent pixel is equal to or greater than the second threshold at an intermediate position between the target interpolation pixel and a pixel at the same column position as the specific pixel. This is a first feature.

  According to the first characteristic configuration of the signal conversion device according to the present invention, pixel data on two consecutive scanning lines is stored, and adjacent pixels in the same scanning line and on both scanning lines located in the same column are stored. The interpolation method can be determined for each pixel on the interpolation line only by measuring the difference value of the pixel data between the pixels and comparing the magnitude relationship with a predetermined threshold value. Therefore, since interpolation data is calculated only by performing simple four arithmetic operations, complicated control is unnecessary and it can be realized with a simple circuit. Further, since it is not necessary to determine a plurality of weights as in the conventional method 3, there is no concern that noise is generated in the pixel data after interpolation depending on the setting of the weights, and at least the first scan line and the second scan It is sufficient that there is a line memory for storing each pixel data on the line, and the required number of memories is greatly reduced as compared with the conventional method 1 which requires a plurality of field memories for storing pixel data in field units. As a result, the circuit scale and power consumption can be reduced.

  Further, when the difference value of pixel data between pixels on both scanning lines located in the same column is equal to or greater than a predetermined first threshold, the pixel data is large on any one scanning line (first specific scanning line). When a change (change greater than or equal to the second threshold) is indicated, the value of the pixel data does not show a large change on the other scanning line (second specific scanning line) at the same column position as the change position. Suggests that. This means that if the scanning direction is the horizontal direction, the image data does not change in the vertical direction, but changes in the oblique direction with a certain angle. It will be.

  That is, even on the second specific scanning line, it is not the same column position as the position showing a large change on the first specific scanning line, but it is suggested that there is a pixel position showing a large change similarly to the first specific scanning line. Is done.

  Therefore, the in-line difference detection means searches for a location where the difference value is equal to or greater than the second threshold at the pixel position after the change position on the second specific scanning line, and specifies the specified on the interpolation line. The interpolation method is determined so that the difference value of the pixel data between the adjacent pixel and the pixel in the same column as that of the target pixel is equal to or greater than the second threshold value. Thereby, even when the image data changes in an oblique direction with a certain angle, the interpolation process can be smoothly performed without noise.

  Further, in the signal conversion device according to the present invention, in addition to the first feature configuration, the interpolation processing determination unit may be configured such that, from the target interpolation pixel to a pixel located before the intermediate position on the interpolation line. For the pixel, the value of the pixel data relating to the pixel at the same column position on the second specific scanning line is adopted, and the pixel positioned from the intermediate position to the same column position as the specific pixel is on the first specific scanning line. The second feature is that the interpolation processing is determined by adopting the pixel data values relating to the pixels at the same column position.

  According to the second characteristic configuration of the signal conversion device according to the present invention, it is possible to cause a change in the value of the pixel data equal to or greater than the second threshold at the intermediate position on the interpolation line, and to change the other pixels. As for the data, it is only necessary to adopt the value of pixel data on a specific scanning line related to the same column position, so that smooth image data can be realized by simple interpolation processing.

  Further, in the signal conversion device according to the present invention, in addition to the first or second feature configuration, the interpolation processing determination unit is arranged at the same column position as the target interpolation pixel on the interpolation line to be an interpolation method determination target. If the determination result of the inter-line difference detection means is less than the first threshold, the pixel data of the target interpolation pixel is the pixel on the first scanning line and the second scanning line at the same column position as the target interpolation pixel. A third feature is to perform an interpolation process that employs an average value of data.

  In the signal converter according to the present invention, in addition to any one of the first to third characteristic configurations, the first line memory is sequentially input with pixel data including interlaced scanning signals, A fourth feature is that the second line memory is configured such that when pixel data for one scanning line is stored in the first line memory, the pixel data is sequentially input from the first line memory. .

  Further, the signal conversion device according to the present invention, in addition to any one of the first to fourth feature configurations, a third line memory for storing the interpolation pixel data generated by the interpolation image data generation unit, Output means for alternately reading out and outputting the pixel data on the second scanning line from the second line memory and the interpolated pixel data from the third line memory for each scanning line. It is characterized by.

  The signal conversion method according to the present invention is a signal conversion method for generating interpolated pixel data from a video signal of an interlace scanning signal system by scanning line interpolation and converting it into a video signal of a progressive scanning signal system. A first step of storing pixel data on the line and pixel data on the second scan line before one horizontal synchronization period of the first scan line, and located in the same column on the first scan line and the second scan line A second step of determining whether or not a difference value of pixel data is greater than or equal to a first threshold; and whether or not the difference value of adjacent pixel data is greater than or equal to a second threshold for each of the first scan line and the second scan line A third step of determining whether or not, a fourth step of determining an interpolation method for each pixel based on the determination results of the inter-line difference detection means and the in-line difference detection means, and the stored And reading out pixel data on one scanning line as well as on the second scanning line, and generating interpolated pixel data based on the interpolation method determined in the fourth step, and the fourth step comprises: If the determination result of the second step is equal to or greater than the first threshold at the same column position as the target interpolation pixel on the interpolation line that is the interpolation method determination target, the same column position based on the determination result of the third step When one of the scanning lines in which the difference value of the pixel data of the pixel adjacent to the pixel in the pixel and the pixel data adjacent to the pixel in the front and rear is greater than or equal to the second threshold is searched from within the first and second scanning lines In this case, the scanning line is specified as the first specific scanning line, and on the second specific scanning line which is the other scanning line, the third step is performed from the same column position toward the scanning direction. A pixel whose determination result is greater than or equal to the second threshold value is identified as a specific pixel, and an adjacent pixel is located on the interpolation line between the target interpolation pixel and a pixel at the same column position as the specific pixel. The interpolation method is determined such that the difference value of the pixel data between and becomes equal to or greater than the second threshold value.

  According to the configuration of the present invention, a smooth interpolation image can be obtained with a simple configuration while suppressing the circuit scale and power consumption.

[First Embodiment]
In the following, a first embodiment of a signal conversion apparatus according to the present invention (hereinafter referred to as “the present apparatus” as appropriate) and a signal conversion method (hereinafter referred to as “the present method” as appropriate) are shown in FIGS. This will be described with reference to each figure.

  FIG. 1 is a block diagram showing a schematic configuration of the apparatus of the present invention. As shown in FIG. 1, the inventive device 1 is configured such that when an interlace scanning signal si is input, a progressive signal sp is output after performing a predetermined calculation. The apparatus 1 of the present invention includes line memories 2a, 2b, 3, inter-line difference detection means 4, in-line difference detection means 5a, 5b, interpolation processing determination means 6, interpolation pixel data generation means 7, and output means 8. It is prepared for.

  The line memories 2a and 2b store pixel data of two continuous lines in one field composed of an interlace scanning signal si given from the outside of the device 1 of the present invention. Specifically, the line memory 2a stores pixel data of a certain scanning line (hereinafter referred to as “first scanning line”) composed of the interlace scanning signal si, and the line memory 2b has already been stored in the line memory 2a. The stored pixel data of the scanning line one horizontal synchronization period before the first scanning line (hereinafter referred to as “second scanning line”) is given from the line memory 2a and stored.

  The inter-line difference detecting means 4 determines whether or not a difference value between pixel data located in the same column on the first scanning line and the second scanning line is equal to or greater than a predetermined threshold (hereinafter referred to as “first threshold”). The determination result is output to the interpolation process determining means 6.

  Further, the in-line difference detection means 5a, 5b has a predetermined threshold value (hereinafter referred to as “second threshold value”) in which the difference value between adjacent pixel data adjacent to either one of the first scanning line and the second scanning line. ”) Or not, and the determination result is output to the interpolation process determining means 6. In the following embodiment, the difference value of the pixel data from the adjacent pixel one pixel before is compared with the second threshold value, and the result is output. Alternatively, the difference value may be calculated and compared with the second threshold value.

  The interpolation processing determining means 6 determines an interpolation processing method based on the determination results given from the inter-line difference detecting means 4 and the in-line difference detecting means 5a and 5b, and the determined interpolation processing method is used as interpolation pixel data. Output to the generating means 7.

  The interpolated pixel data generating means 7 reads out the pixel data on the first scanning line from the line memory 2a and the pixel data on the second scanning line from the line memory 2b, and uses these pixel data to interpolate the processing method determination means 6 Interpolation pixel data is generated based on the interpolation processing method given by (1), and the generated interpolation pixel data is stored in the line memory 3.

  The output unit 8 reads out and outputs pixel data on the second scanning line from the line memory 2b, and then reads out and outputs the interpolated pixel data from the line memory 3. Hereinafter, similarly, pixel data for one scanning line stored in the line memory 2b and pixel data for one scanning line stored in the line memory 3 are alternately read and output. As a result, the progressive scanning signal sp is generated from the output means 8.

  The inter-line difference detecting means 4, the in-line difference detecting means 5a and 5b, the interpolation process determining means 6, and the interpolated pixel data generating means 7 are hardware configured so that the above arithmetic processing can be realized by an analog circuit, a digital circuit or the like. Hardware means, or software means configured to be able to implement the arithmetic processing on predetermined hardware means.

  Hereinafter, the signal conversion method of the device 1 of the present invention will be specifically described using numerical examples (both are expressed in decimal numbers). 2 and 3 are pixel data configuration diagrams for explaining a signal conversion method by the apparatus of the present invention.

  As shown in FIG. 2A, it is assumed that the first scanning line 11 composed of the pixels 11a, 11b,... Is input to the device 1 of the present invention as an interlace scanning signal si. As described above, the second scanning line 12 corresponds to a scanning line before one horizontal synchronization period with respect to the first scanning line 11, and is stored in the line memory 2a before the first scanning line 11 is input. Data of each pixel (12a, 12b,...) Constituting the second scanning line 12 is stored. Hereinafter, the pixels constituting the first scanning line 11 are collectively referred to as “pixels 11x”, and the pixels constituting the second scanning line 12 are collectively referred to as “pixels 12x”.

  As described above, when the data of all the pixels 11x are stored in the line memory 2a, the data of the pixels 12x already stored in the line memory 2a are stored in the line memory 2b.

  The inter-line difference detecting means 4 includes two pixels (for example, pixels) having the same column position in each data of the pixel 11x stored in the line memory 2a and each data of the pixel 12x stored in the line memory 2b. 11a and 12a, 11b and 12b, etc.) are calculated, it is determined whether or not the difference value is greater than or equal to the first threshold value, and the determination result is provided to the interpolation process determining means. It should be noted that the numbers written in the frame indicating each pixel in the drawing indicate the value of the pixel data.

  For example, the difference value between the data of the pixels 11a and 12a is “2”. Here, if the first threshold value is set to 50, the difference value between the data of the pixels 11a and 12a is less than the first threshold value. In this case, the fact that the difference value between the data of the pixels 11a and 12a is less than the first threshold value is output to the interpolation process determining means 6. Similarly, the fact that the difference value between the data of the pixels 11b and 12b is also less than the first threshold value is output to the interpolation process determining means 6.

  On the other hand, when the difference value between the data of the pixels 11c and 12c is calculated, it is “100”, which is equal to or greater than the first threshold value. In this case, the fact that the difference value between the data of the pixels 11c and 12c is greater than or equal to the first threshold value is output to the interpolation process determining means 6. Similarly, the fact that the difference value between the data of the pixels 11d and 12d is also equal to or greater than the first threshold is output to the interpolation process determining means 6.

  As described above, the inter-line difference detection unit 4 sequentially determines whether or not the difference value between the data of the two pixels in the same row position relationship on the first scanning line and the second scanning line is equal to or larger than the first threshold value in the scanning order. The result is given to the interpolation process determining means 6.

  The in-line difference detection means 5a sequentially selects data related to two adjacent pixels from the pixels 11x stored in the line memory 2a in the scanning order (for example, data of the pixels 11a and 11b), and the difference value is selected. While calculating, it is determined whether the said difference value is more than the said 2nd threshold value. Similarly, the in-line difference detection means 5b sequentially selects data relating to two adjacent pixels from the pixel 12x stored in the line memory 2b in the scanning order (for example, data of the pixel data 12a and 12b), and the difference therebetween. A value is calculated, and it is determined whether the difference value is equal to or greater than the second threshold value.

  For example, when the difference value between the pixel data 11a and 11b is calculated, it is “0”. Here, if the second threshold value is set to 50, the difference value between the data of the pixels 11a and 11b is less than the second threshold value. In this case, the in-line difference detection unit 5a outputs to the interpolation processing determination unit 6 that the difference value between the data of the pixels 11a and 11b is less than the second threshold value. Similarly, for each combination of the pixels 11b and 11c and 11c and 11d, the fact that the difference value of each data is less than the second threshold value is output to the interpolation process determining means 6.

  On the other hand, when the difference value between the data of the pixels 11d and 11e is calculated, it is “100”, which is equal to or greater than the second threshold value. In this case, the fact that the difference value between the data of the pixels 11d and 11e is greater than or equal to the second threshold value is output to the interpolation process determining means 6. The in-line difference detection unit 5b outputs the determination result for the data related to two adjacent pixels constituting the pixel 12x to the interpolation processing determination unit 6 in the same manner.

  The interpolation processing determination means 6 determines an interpolation processing method by the following method based on the determination results sent from the inter-line difference detection means 4 and the in-line difference detection means 5a and 5b.

  The interpolation process determination means 6 sequentially determines an interpolation process method in the same direction as the scanning direction for each interpolation pixel on the interpolation line 13 constituting the interpolation pixel group, and outputs it to the interpolation pixel data generation means 7. Then, the interpolation pixel data generation means 7 reads each data of the pixel 11x and each data of the pixel 12x from the line memories 2a and 2b, and performs an operation based on the interpolation processing method determined by the interpolation processing determination means 6. Thus, data of one interpolation pixel on the interpolation line 13 is determined. The interpolation pixel data generation means 7 sequentially calculates interpolation pixel data in the same direction as the scanning direction for each interpolation pixel on the interpolation line by the same procedure. The data values of all the interpolation pixels on the interpolation line 13 calculated in this way are stored in the line memory 3.

  The interpolation process determination means 6 first confirms the determination result of the inter-line difference detection means 4 associated with the same column as the target interpolation pixel that is the interpolation process method determination target (step # 1). If the determination result of the inter-line difference detection unit 4 is less than the first threshold (“Yes” in step # 1), the same as the target interpolation pixel on the first scanning line 11 and the second scanning line 12 It is determined that the interpolation process is performed by calculating the average value of the data of the pixels located in the column (step # 2).

  For example, when the target interpolation pixel is 13a (see FIG. 2B), the difference value between the data of the pixels 11a and 12a is “2”, which is less than the first threshold value. The data value of the interpolation pixel 13a is determined as “1”. By the same method, the data of the interpolation pixel 13b is also determined as “1”.

  On the other hand, when the determination result of the inter-line difference detection unit 4 is equal to or greater than the first threshold value (“No” in Step # 1), the determination result of the inter-line difference detection unit 4 is the pixel data indicating that the determination result is less than the first threshold value. The pixel position where the combination exists is sequentially searched in the same direction as the scanning direction (step # 3).

  For example, when the target interpolation pixel is 13c (see FIG. 2C), the difference value between the data of the pixels 11c and 12c is “100”, which is equal to or greater than the first threshold value. At this time, when the magnitude relationship between the first threshold value and the data difference value of the pixels 11d and 12d in the same column pixel position of the target interpolation pixel 13d one pixel after the pixel located on the right side in the drawing is seen, the difference value is also “100”. And is greater than or equal to the first threshold. Further, when the magnitude relationship between the data difference value of the pixels 11e and 12e in the same column pixel position of the target interpolation pixel 13e after one pixel and the first threshold value is seen, the difference value is “0” and a value less than the first threshold value is obtained. Show. Accordingly, by confirming the determination results of the in-line difference detection means 5a and 5b, the pixel position where the combination of pixel data whose determination result of the inter-line difference detection means 4 is less than the first threshold exists is the pixels 11e and 12e. It can be seen that the interpolation pixel in the same column as the pixel position is 13e.

  In such a case, if the interpolation process similar to the method according to step # 2 is performed on the interpolation pixel 13c and the interpolation pixel 13d that is one pixel before the interpolation pixel 13e, noise may be generated at that location. is there. That is, by the above process, an interpolation pixel that does not perform the interpolation process using the method according to step # 2 and needs to go through further steps to determine the interpolation method (hereinafter referred to as “target interpolation pixel” as appropriate) Specified (step # 4). In the case of the above example, the interpolation pixels 13c and 13d are specified as target interpolation pixels. For these target interpolation pixels, the interpolation method is determined after the following steps (# 5 to # 9).

  First, among the target interpolation pixels, an interpolation pixel in which the interpolation processing method related to the previous interpolation pixel is already determined in step # 2 is selected (step # 5). In the example of FIG. 2, since it has already been decided to adopt the method according to step # 2 as the interpolation data calculation method for the previous interpolation pixel 13b, in step # 5, the interpolation pixel 13b is one pixel after. The interpolation pixel 13c is first selected.

  Next, by confirming the determination results of the in-line difference detection means 5a and 5b, the pixel one pixel before the pixel data on both scanning lines at the same column position as the interpolation pixel selected in step # 4 A scanning line in which the amount of change from the data is equal to or greater than the second threshold (hereinafter referred to as “first specific scanning line” as appropriate) is searched (step # 6).

  The difference value between the pixel data of the pixel 11c in the same column position as the interpolated pixel 13c on the first scanning line 11 and the pixel 11b one pixel before the pixel 11c is 2, which is less than the second threshold value. On the other hand, the difference value of the pixel data of the pixel 12c in the same column position as the target interpolation pixel 13c on the second scanning line 12 and the pixel 12b one pixel before the pixel 12c is 100, which is greater than or equal to the second threshold value. That is, by checking the determination result of the in-line difference detection means 5a, 5b, the difference value between the pixel position pixel data and the pixel data one pixel before the interpolation pixel 13c is equal to or larger than the second threshold value. It turns out that it is the 2nd scanning line 12 (refer FIG.2 (d)). That is, it can be seen that the first specific scanning line is the second scanning line 12.

  Next, as the interpolation data of the interpolation pixel selected in step # 5, the same column as the interpolation pixel on the scanning line not selected in step # 6 (hereinafter referred to as “second specific scanning line” as appropriate). It is decided to perform the interpolation process by adopting the pixel data related to the position (step # 7).

  According to FIG. 2D, the interpolation pixel data generation means 7 causes the data of the interpolation pixel 13c to be the scanning line (second specific scanning line) not selected in step # 6, that is, the first scanning line 11 concerned. It is determined to be “0”, which is the same as the pixel data of the pixel 11c at the same column position as the interpolation pixel 13c (see FIG. 3A).

  Next, the result of the in-line difference detection means (5a or 5b) that compares the difference between the adjacent pixel data for the second specific scanning line and the second threshold value is used as the pixel at the same column position as the interpolation pixel. Are sequentially confirmed in the same direction as the scanning direction, and a pixel whose difference value of the data of the previous pixel is equal to or more than the second threshold is specified (hereinafter referred to as “specific pixel” as appropriate), and the pixel on the interpolation line An interpolation pixel in the same column as the specific pixel is specified (step # 8).

  According to FIG. 3A, in the second specific scanning line, that is, the first scanning line 11, when searching from the pixel at the same column position as the interpolation pixel 13c (that is, the pixel 11c) in the same direction as the scanning direction, the pixel 11e It can be seen that the difference value of the data of the previous pixel 11d is equal to or greater than the second threshold value. That is, the pixel 11e is specified as the specific pixel. Therefore, the interpolation pixel 13e is specified as a pixel in the same column as the specific pixel 11e on the interpolation line (see FIG. 3B).

  By the above step # 5 to step # 8, the change position where the difference value with the adjacent pixel data is greater than or equal to the second threshold value in each of the first scanning line 11 and the second scanning line 12 is specified.

  Next, the data in the pixels in the same column on the first specific scanning line selected in step # 6 is adopted as the interpolation data of the interpolation pixel one pixel before the interpolation pixel specified in step # 8 on the interpolation line. Thus, it is determined to perform the interpolation process (step # 9).

  According to FIG. 3B, the data of the interpolation pixel 13d that is one pixel before the interpolation pixel 13e specified in step # 8 by the interpolation pixel data generation means 7 is selected in step # 6. The line data, that is, “100”, which is the same as the pixel data of the pixel 12d in the same column as the interpolation pixel 13d on the second scanning line 12, is determined (see FIG. 3C).

  Since the interpolation pixel 13e becomes “Yes” in step # 1 as described above, the average of the data of the pixels 11e and 12e on both scanning lines in the same column as the interpolation pixel 13e is determined in accordance with step # 2. The value is adopted and determined to be “100” (see FIG. 3D).

  A method for calculating pixel data of the interpolated pixels on the interpolated line is determined according to steps # 1 to # 9. Then, as described above, the interpolation pixel data generation means 7 calculates the interpolation data of each interpolation pixel on the interpolation line based on the interpolation method determined in this way, and stores it in the line memory 3. Then, the output means 8 alternately reads and outputs the pixel data on the second scanning line 12 from the line memory 2b and the interpolation pixel data on the interpolation line 13 from the line memory 3 for each scanning line. As a result, the progressive scanning signal sp is output.

  In step # 1, it is determined that the determination result of the inter-line difference detection means 4 is equal to or greater than the first threshold (“No” in step # 1). This suggests that the pixel data does not show a great change on the other scanning line in the same column as the change position where the pixel data shows a big change on any one of the scanning lines. This means that if the scanning direction is the horizontal direction, the image data does not change in the vertical direction, but changes in the oblique direction with a certain angle. It will be.

  Therefore, if the change position where the pixel data changes greatly in each of the first scanning line 11 and the second scanning line 12 can be specified, it can be understood that the entire image data changes greatly along the line connecting the change positions. Is possible. That is, on the interpolation line 13 that interpolates between the first scanning line 11 and the second scanning line 12, an image having an oblique angle can be obtained if it can be greatly changed at a position that intersects the line connecting the change positions. Even for data, the edge (contour line) of the image data after interpolation can be clarified, and the occurrence of noise is suppressed.

  Here, when viewed in a direction orthogonal to the scanning direction, the interpolation line 13 constitutes an intermediate position between the first scanning line 11 and the second scanning line 12. Therefore, the position on the interpolation line 13 that intersects the line connecting the change positions where the pixel data changes greatly in each of the first scan line 11 and the second scan line 12 corresponds to the intermediate position of the change positions. Therefore, on the interpolation line 13, a change equal to or greater than the second threshold value is shown between two adjacent pixels at an intermediate position between the change position column of the first scan line 11 and the change position column of the second scan line 12. By performing the interpolation process, the edge of the image data after the interpolation can be clarified.

  When the interpolation process is performed according to the above method, if a change greater than or equal to a predetermined threshold (second threshold) occurs in one scanning line and another scanning line before the one horizontal synchronization period, the interpolation line In the above, it is possible to perform the interpolation processing so that two adjacent pixels at a middle position between the change positions have a change equal to or greater than the second threshold value.

  That is, referring to FIG. 2A, on the first scanning line 11, a change greater than or equal to the second threshold occurs between the pixels 11d and 11e, and on the second scanning line 12, the pixel 12b and A change greater than or equal to the second threshold value occurs between 12c. Then, referring to FIG. 3D, on the interpolation line 13 after the interpolation process, a change greater than or equal to the second threshold value occurs between the interpolation pixels 13c and 13d. Therefore, even with an image having an edge in an oblique direction, such an interpolation process can generate an interpolated image without erroneously determining the change point in the oblique direction.

  Then, the pixel data difference between the pixels in the same column and another scan line before one horizontal synchronization period, and the pixel data difference between adjacent pixels in each scan line are calculated, and based on the calculation result. Therefore, the interpolation data is calculated simply by performing the simple four arithmetic operations based on the pixel data on one of the scanning lines sandwiching the interpolation line, or on the pixel data on both scanning lines sandwiching the interpolation line. Such control is not necessary and can be realized with a simple circuit. Furthermore, since it is not necessary to define a plurality of weights as in the conventional method 3, there is no concern that noise is generated in the pixel data after interpolation depending on the setting of the weights.

  Furthermore, according to the device 1 of the present invention, it is sufficient that there is at least a line memory for storing each pixel data on the first scanning line and the second scanning line, and a plurality of field memories for storing the pixel data in a field unit are necessary. As compared with the conventional method 1, the number of necessary memories can be greatly reduced, and thereby the circuit scale and power consumption can be reduced.

[Second Embodiment]
Hereinafter, a second embodiment (hereinafter referred to as “this embodiment” as appropriate) of the device of the present invention and the method of the present invention will be described with reference to FIGS. Since the configuration of the device of the present invention is the same as that of the first embodiment, the description thereof is omitted.

  In the example (FIGS. 2 and 3) in the first embodiment, on the interpolation line 13, the interpolation pixel selected in step # 4 and the interpolation pixel one pixel before the interpolation pixel specified in step # 7. Were in an adjacent relationship. However, in some cases, these interpolated pixels may not be adjacent. An example of the interpolation method in such a case will be described below with reference to FIGS.

  4 and 5 are pixel data configuration diagrams for explaining another example of the signal conversion method by the device of the present invention. In FIG. 4, in order to avoid confusion, the reference numerals different from those in FIGS.

  Referring to FIG. 4A, the interpolation processing methods for the interpolation pixels 23a and 23b are all performed on the first scanning line 21 and the second scanning line 22 by the above steps # 1 and # 2. It is determined by calculating the average value. Since the interpolation processing method for the interpolation pixel 23c is “No” in Step # 1, the method according to Step 2 (average value calculation) is not adopted, and the process proceeds to Steps after Step # 3.

  At this time, in step # 3, the pixel positions where the combination of pixel data indicating that the determination result of the inter-line difference detection means 4 is less than the first threshold are pixels 21g and 22g, and the interpolation pixels in the same column as the pixels are It turns out that it is 23g (refer FIG.4 (b)). Therefore, four pixels of the interpolation pixels 23c to 23f are specified by the step # 4 as the interpolation pixels that proceed to the steps after the step # 5.

  Next, in step # 5, the interpolation pixel 23c is selected from the four interpolation pixels as the interpolation pixel for which the interpolation processing method related to the previous interpolation pixel is already determined in step # 2.

  Next, in step # 6, among the pixel data on both scanning lines in the same column as the interpolation pixel 23c, the scanning line whose amount of change from the previous pixel data is equal to or more than the second threshold, that is, the first identification. It is confirmed that the scanning line is the second scanning line 22. Then, in step # 7, as the interpolation data of the interpolation pixel 23c, the scanning line (second specific scanning line) not selected in step # 6, that is, the pixel of the pixel 21c in the same column position on the first scanning line 21 is selected. By adopting the data value, it is determined to perform the interpolation process (see FIG. 4C).

  Next, in step # 8, on the first scanning line 21, the pixels in the same column as the interpolation pixel 23d (that is, the pixel 21d) are sequentially confirmed in the same direction as the scanning direction, and the difference in the data of the pixel one pixel before is determined. The pixel 21g is specified as a pixel position whose value is equal to or greater than the second threshold (specific pixel), and the interpolation pixel 23g in the same column as the specific pixel 21g on the interpolation line 23 is specified.

  Next, in step # 9, the first specific scanning line selected in step # 6, that is, the second scanning line 22 is selected as the interpolation data of the interpolation pixel 23f one pixel before the interpolation pixel 23g specified in step # 8. It is determined that the interpolation process is performed by adopting the pixel data value of the pixel 22f in the upper same column (see FIG. 4D).

  At this time, the interpolation processing method for the interpolation pixels 23d and 23e cannot be determined through the steps # 1 to # 8 (see FIG. 4D).

  As described above, when the interpolation pixel (23c) selected in step # 4 and the interpolation pixel (23f) that is one pixel before the interpolation pixel specified in step # 8 are not adjacent to each other, they exist between them. For the interpolation pixels to be interpolated, interpolation processing can be further performed by the following method.

  As an example, after step # 9, in step # 10, when the number of interpolation pixels for which the interpolation processing method has not yet been determined is an even number, the intermediate position of the interpolation pixel is used as a boundary and the intermediate position is preceded. For the interpolated pixel located at, the same processing as in step # 7 is performed, and for the interpolated pixel located after the intermediate position, the same processing as in step # 9 is performed.

  Specifically, since the undetermined interpolation pixels are 23d and 23e and an even number (two), as shown in FIG. 5A, the intermediate position of these interpolation pixels (the boundary between the interpolation pixels 23d and 23e). For the interpolated pixel 23d positioned before (on the left side in the drawing), the pixel data value of the pixel 21d in the same column on the first scanning line 21 is adopted, and after the intermediate position (on the right side in the drawing). For the interpolation pixel 23e located at, the pixel data value of the pixel 22e in the same column on the second scanning line 22 is adopted.

  Even in the case of the above method, as in the first embodiment, these scans occur when a change of a predetermined threshold value or more occurs in one scan line and another scan line before one horizontal synchronization period. On the interpolation line sandwiched between the lines, the interpolation process can be performed so as to have a change equal to or greater than the second threshold value at an intermediate position between the change positions. That is, taking the case of FIGS. 4 and 5 as an example, the change in the first scanning line 21 is not less than the second threshold value between the pixels 21f and 21g, and the second scanning line 22 has the second threshold. It is between the pixels 22b and 22c that the change more than a threshold value has arisen. When the method according to the present embodiment is used under such a state, a change greater than or equal to the second threshold value occurs between the pixels 23d and 23e on the interpolation line 23, and is intermediate between the respective change positions. Interpolation processing can be performed so as to have a change greater than or equal to the second threshold at the position. As a result, even for an image having an edge in an oblique direction, the edge of the image data after interpolation can be clarified with a simple circuit configuration without erroneously determining the change point in the oblique direction. Can be suppressed.

  On the other hand, when the number of interpolation pixels for which the interpolation processing method has not yet been determined is an odd number, if interpolation processing is to be executed based on the above method, it will be shifted from the intermediate position by one pixel on either side. In this case, the same interpolation may be performed by shifting by one pixel to the side where the difference value of the first scanning line 21 and the second scanning line 22 is changed more than the threshold value.

  For example, in the case of the configuration example shown in FIG. 5B, the difference value between the pixels 22 b and 22 c on the second scanning line 22 rather than the difference value between the pixels 21 g and 21 h on the first scanning line 21. Is bigger. Therefore, in this case, interpolation can be performed so that a change equal to or greater than the threshold value occurs on the interpolation line 23 from the interpolation pixel 23d to the interpolation pixel 23e. That is, for the interpolation pixel 23d, the value of the pixel data at the same column position on the first scanning line 21 is adopted, and for the interpolation pixel 23e and 23f, the value of the pixel data in the same column on the second scanning line 22 is adopted. Adopted (see FIG. 5C). Even when interpolation processing is performed in this way, even if the image has an edge in the diagonal direction, the edge of the image data after interpolation is clarified by a simple circuit configuration without misjudging the change point in the diagonal direction. Can be.

  In the above case, if the difference values of the first scanning line 21 and the second scanning line 22 where the change of the second threshold value or more is the same, any of the predetermined values from the intermediate position is determined. Alternatively, the interpolation process may be performed so as to cause a change of the second threshold value or more by shifting by one pixel in one direction.

[Another embodiment]
Hereinafter, another embodiment will be described.

  <1> In the above-described embodiment, the first specific scanning line is searched in Step # 6. However, in some cases, the first specific scanning line may not be detected as a result of the search. Specifically, the difference between the pixel data on the first scan line and the pixel data on the second scan line in a certain pixel column as a result of the gentle change in the pixel data values on the first and second scan lines. Corresponds to the case where the value is equal to or greater than the first threshold.

  In such a case, for example, as in step # 2, the interpolation processing may be determined by calculating the average value of the data of the pixels located in the same column as the target interpolation pixel. This is because, as described above, the fact that the first specific scanning line was not detected in step # 6 is assumed that the pixel data values are gently changing on both scanning lines. This is because even if the average value of the data of the pixels in the position is calculated and the interpolation process is performed, no visual noise is generated at that location.

  Further, in the above case, the method is not limited to the method of calculating the average value as in step # 2, and other interpolation processing methods generally used conventionally may be used.

  <2> In step # 2, the interpolation process is performed by calculating the average value of the data of the pixels located in the same column as the target interpolation pixel. However, other interpolation processes conventionally used in general are used. You may use the method. However, in view of the fact that an image with less noise can be generated by simple processing, it is preferable to adopt the method described in Step # 2 in which interpolation processing is performed by calculating an average value.

<3> In each of the above-described embodiments, a value serving as a determination criterion of the inter-line difference detection unit 4 is “
Although the “first threshold value” and the value serving as the determination criterion for the in-line difference detection means 5a and 5b are described as the “second threshold value”, these values may be different values or the same value.

  <4> In each of the above-described embodiments, the in-line difference detection means 5a and 5b sequentially apply the difference value of the pixel data and the second threshold value for all adjacent two pixels on the first scanning line 11 and the second scanning line 12, respectively. The comparison result is output to the interpolation processing determination means 6, but the determination result of the interline difference detection means 4 is not less than the first threshold value (“No” in step # 1). Only in this case, the in-line difference detection means 5a, 5b may be configured to execute only the determination of the difference value at the location necessary for executing steps # 3 to # 8.

  <5> When the change pattern of the value of the image data is generated in the same direction as the scanning direction, the determination result of the inter-search line difference detecting means 4 is still obtained even when the last column on the scanning line is searched in step # 3. It is conceivable that a pixel position where there is a combination of pixel data that indicates less than the first threshold cannot be detected. In such a case, after recognizing that the change pattern of the value of the image data is generated in the same direction as the scanning direction, the two pixels corresponding to the same pixel column on both scanning lines sandwiching the interpolation line are used. Processing for calculating the average value of the data values (processing similar to step # 2) may be performed. When such an interpolation process is performed, the interpolation process can be performed on the interpolation line so that the pixel data value changes in parallel to the interpolation line. However, an image with a clear change position of the pixel data can be obtained without appearing as large noise.

The block diagram which shows schematic structure of the signal converter which concerns on this invention Pixel data configuration diagram (1) for explaining an example of a signal conversion method by the signal conversion apparatus according to the present invention Pixel data block diagram (2) for demonstrating the example of the signal conversion method by the signal converter concerning this invention Pixel data configuration diagram (1) for explaining another example of the signal conversion method by the apparatus of the present invention Pixel data configuration diagram (2) for explaining another example of the signal conversion method by the apparatus of the present invention Schematic diagram showing the conventional interpolation method Schematic diagram showing another conventional interpolation method

Explanation of symbols

1: Signal converters 2a, 2b, 3: Line memory 4: Inter-line difference detecting means 5a, 5b: In-line difference detecting means 6: Interpolation process determining means 7: Interpolated pixel data generating means 8: Output means 11: First scanning line 11a, 11b,...: Each pixel on the first scanning line 11x: Generic name of pixels on the first scanning line 12: Second scanning line 12a, 12b,...: On the second scanning line Each pixel 12x: Generic name of pixels on the second scanning line 13: Interpolation lines 13a, 13b, ...: Each interpolation pixel on the interpolation line 21: First scanning lines 21a, 21b, ...: On the first scanning line Each pixel 21x: generic name of pixels on the first scanning line 22: second scanning line 22a, 22b,...: Each pixel on the second scanning line 22x: generic name of pixels on the second scanning line 23: interpolation line 23a, 23b , :: Interpolation pixels on the interpolation line 51: First scanning lines 51a, 61b, ...: Each pixel on the first scanning line 52: Second scanning lines 52a, 62b, ...: Each on the second scanning line Pixel 53: Interpolation line 53a, 63b,...: Each interpolation pixel on the interpolation line 61: First scanning line 61a, 61b,...: Each pixel on the first scanning line 62: Second scanning line 62a, 62b , ...: Each pixel on the second scanning line 63: Interpolation lines 63a, 63b, ...: Each interpolation pixel on the interpolation line si: Interlace scanning signal sp: Progressive scanning signal

Claims (6)

A signal conversion device that generates interpolated pixel data from a video signal of an interlaced scanning signal system by scanning line interpolation and converts it into a video signal of a progressive scanning signal system,
A first line memory for storing pixel data on the first scan line;
A second line memory for storing pixel data on the second scanning line before one horizontal synchronization period of the first scanning line;
An inter-line difference detecting means for determining whether or not a difference value between pixel data located in the same column on the first scanning line and the second scanning line is equal to or greater than a first threshold;
In-line difference detection means for determining whether the difference value of adjacent pixel data is equal to or greater than a second threshold for each of the first scan line and the second scan line;
Interpolation processing determining means for determining an interpolation method for each pixel based on determination results of the inter-line difference detecting means and the in-line difference detecting means;
Interpolated pixel data generating means for reading out pixel data stored in the first line memory and the second line memory and generating interpolated pixel data based on the interpolation method determined by the interpolation processing determining means. ,
The interpolation processing determination means is
Based on the determination result of the in-line difference detection means if the determination result of the inter-line difference detection means is equal to or greater than the first threshold at the same column position as the target interpolation pixel on the interpolation line to be determined as the interpolation method. The scanning line in which the difference value of the pixel data of the adjacent pixel adjacent to the pixel at the same column position and any one before and after is searched from the first and second scanning lines and searched. In this case, the scanning line is identified as the first specific scanning line, and the determination result of the in-line difference detection means from the same column position toward the scanning direction on the second specific scanning line which is the other scanning line. A pixel that indicates the second threshold value or more as a specific pixel,
On the interpolation line, an interpolation method is determined so that a difference value of pixel data between an adjacent pixel and an adjacent pixel is equal to or greater than the second threshold value at an intermediate position between the target interpolation pixel and a pixel at the same column position as the specific pixel. A signal converter characterized by that. The interpolation processing determination means is
On the interpolation line, for the pixels located before the intermediate position from the target interpolation pixel, the value of the pixel data relating to the pixel at the same column position on the second specific scanning line is adopted, and the intermediate position To the pixel located in the same column position as the specific pixel is determined to perform the interpolation process by adopting the value of the pixel data relating to the pixel at the same column position on the first specific scanning line. The signal conversion apparatus according to claim 1. The interpolation processing determination means is
If the determination result of the inter-line difference detection means is less than the first threshold at the same column position as the target interpolation pixel on the interpolation line to be determined as the interpolation method, the target interpolation is used as pixel data of the target interpolation pixel. 3. The signal conversion apparatus according to claim 1, wherein an interpolation process is performed to employ an average value of pixel data on the first scanning line and the second scanning line at the same column position as the pixel. 4. The first line memory sequentially receives pixel data composed of interlaced scanning signals,
The second line memory is configured such that when pixel data for one scanning line is stored in the first line memory, the pixel data is sequentially input from the first line memory. The signal converter as described in any one of 1-3. A third line memory for storing the interpolated pixel data generated by the interpolated image data generating means;
Output means for alternately reading out and outputting pixel data on the second scanning line from the second line memory and the interpolated pixel data from the third line memory for each scanning line. The signal converter as described in any one of Claims 1-4. A signal conversion method for generating interpolated pixel data from a video signal of an interlaced scanning signal system by scanning line interpolation and converting it into a video signal of a progressive scanning signal system,
A first step of storing pixel data on the first scan line and pixel data on the second scan line before one horizontal synchronization period of the first scan line;
A second step of determining whether or not a difference value between pixel data located in the same column on the first scanning line and the second scanning line is equal to or greater than a first threshold;
A third step of determining whether a difference value of adjacent pixel data is equal to or greater than a second threshold for each of the first scanning line and the second scanning line;
A fourth step of determining an interpolation method for each pixel based on the determination results of the inter-line difference detection means and the in-line difference detection means;
A fifth step of reading out the stored pixel data on the first scanning line and the second scanning line and generating interpolation pixel data based on the interpolation method determined by the fourth step;
The fourth step includes
If the determination result of the second step is equal to or greater than the first threshold at the same column position as the target interpolation pixel on the interpolation line that is the interpolation method determination target, the same column position based on the determination result of the third step When one of the scanning lines in which the difference value of the pixel data of the pixel adjacent to the pixel in the pixel and the pixel data adjacent to the pixel in the front and rear is greater than or equal to the second threshold is searched from within the first and second scanning lines , The scanning line is identified as the first specific scanning line, and the determination result of the third step from the same column position toward the scanning direction on the second specific scanning line which is the other scanning line is the second specific scanning line. Identify a pixel that shows a threshold value or higher as a specific pixel,
On the interpolation line, an interpolation method is determined so that a difference value of pixel data between an adjacent pixel and an adjacent pixel is equal to or greater than the second threshold value at an intermediate position between the target interpolation pixel and a pixel at the same column position as the specific pixel. A signal conversion method characterized by the above.

Images