JP2009038619A - Image processing device and method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing device and method, and program for more surely detecting a black belt. <P>SOLUTION: The image processing device detects a region 11-1 being the black belt by detecting a boundary between black lines which are continuously arranged downward from the upper edge of an input image and a line which is not a black line, and detects a region 11-2 being the black belt by detecting a boundary between lines which are continuously arranged downward from the edge of a prescribed area of a lower side of the input image and are not black lines, and the black line. In addition, the image processing device detects regions 12-1 and 12-2 being the black belt by detecting the positions of boundaries between the regions 12-1 and 12-2 and the central effective image of the input image and performing majority processing of the positions about respective lines of the image obtained by eliminating the region 11-1 and the region 11-2 from the input image. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image processing apparatus, method, and program, and more particularly, to an image processing apparatus, method, and program that can detect a black belt from an image more reliably.

  For example, a so-called black band may be added to the edge of an image such as a television broadcast program for adjusting the aspect ratio. The black belt is provided adjacent to the outside of the effective image that is the image of the content on the image, and is composed of black pixels having a low luminance value.

  Some conventional image processing apparatuses detect a black belt region on an image in order to perform predetermined processing on an image to be displayed. In the detection of the black band, the luminance value of the pixel on the image is compared with the threshold value, and an outer dark area in the image, that is, an area where the luminance value of the pixel is lower than the threshold value is detected. It was an area.

  In addition, some image processing apparatuses include a black band in an image when the maximum value and the minimum value of the luminance values of pixels in a specific region on the image satisfy a predetermined condition ( For example, see Patent Document 1). In this image processing apparatus, a part of the area in the area that is a black band on the image is a specific area for detecting the black band.

JP 2006-229781 A

  However, with the above-described technique, it is difficult to detect a black belt region on an image. For example, in a conventional image processing apparatus, the presence or absence of a black band may be determined based on a comparison result between the luminance value of one pixel and a threshold value, so that it is not dark due to noise or the like on the black band. When there is a pixel, that is, a pixel having a luminance value higher than the threshold value, the position of the pixel may be erroneously determined to be the position of the boundary between the black belt and the effective image.

  In addition, in the method of detecting a black belt using the luminance value of a pixel in a specific area on the image, when a dark image, that is, an image composed of pixels having a low luminance value is displayed in the specific area, Even though there was no black belt on the top, the black belt was sometimes detected.

  Furthermore, if the entire image is dark, it is difficult to determine whether the image processing apparatus has an image with a large black band area or an entire dark image. Depending on the case, a black belt may be detected or not detected from the image.

  The present invention has been made in view of such a situation, and makes it possible to more reliably detect a black belt from an image.

  An image processing apparatus according to an aspect of the present invention is a first black image that is located at each of first to fourth edges of an input image and is an area composed of black pixels having a pixel luminance value smaller than a predetermined threshold value. An image processing apparatus for detecting each of a band to a fourth black band, wherein a predetermined number or more of the black pixels are included in a line composed of pixels arranged in a first direction on the input image. A black line detecting means for detecting a black line, which is a line that is present, and the first detection area from the first end in a first detection region in the vicinity of the first end based on the detection result of the black line. The first black belt is detected by detecting a boundary between the black line continuously arranged in a second direction perpendicular to the direction and a line that is not a black line, and the first black band is detected. In the second detection region in the vicinity of the second end facing the end. Detecting a boundary between the black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection region facing the second end, First black band detecting means for detecting two black bands, and a third black band in the vicinity of the third end on the image obtained by removing the first black band and the second black band from the input image. Based on a detection region and a fourth detection region in the vicinity of the fourth end facing the third end, black pixel detection means for detecting the black pixel, and based on the detection result of the black pixel Then, for each line in the third detection region, pixels that are not the black pixels arranged continuously in the first direction from the end of the third detection region facing the third end; , Detecting a boundary with the black pixel, and for each line in the fourth detection region Boundary detection means for detecting a boundary between the black pixels continuously arranged in the first direction from the fourth end and pixels that are not the black pixels, and for each line in the third detection region The second black band is detected based on the detection result of the boundary of the second black line, and the fourth black band is detected based on the detection result of the boundary for each line in the fourth detection region. Black belt detecting means.

  The image processing apparatus determines whether or not the input image includes a predetermined number or more of the black lines based on the detection result of the black lines, and the predetermined number or more of the black lines are included. In the case where a black line is included, it is possible to further provide determination means that the input image does not include the first black band to the fourth black band.

  The second black belt detecting means determines the position of the third black belt in the input image that has the highest appearance frequency among the positions of the boundaries detected in each line in the third detection region. The position of the boundary is set, and the position with the highest appearance frequency among the positions of the boundary detected in each line in the fourth detection region is set as the position of the boundary of the fourth black belt in the input image. be able to.

  The image processing apparatus includes a detection result of the first black belt to the fourth black belt in the input image and the first black belt to the black in the input image of several frames immediately before the input image. A determination means for determining the final positions of the first black band to the fourth black band of the input image based on the detection result of the fourth black band may be further provided.

  An image processing method or program according to one aspect of the present invention is a first region that is located at each of the first to fourth ends of an input image, and is a region composed of black pixels whose pixel luminance value is smaller than a predetermined threshold value. An image processing method for detecting each of the black belt to the fourth black belt, wherein a predetermined number or more of black pixels are included in a line composed of pixels arranged in a first direction on the input image. A black line that is a detected line, and based on the detection result of the black line, the first direction from the first end in the first detection region in the vicinity of the first end The first black belt is detected by detecting a boundary between the black line continuously arranged in the vertical second direction and a line that is not a black line, and is opposed to the first end. In the second detection area in the vicinity of the second end, By detecting a boundary between the black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection region facing the second end, the second line And a third detection region in the vicinity of the third end on the image obtained by removing the first black strip and the second black strip from the input image, and the third end The black pixel is detected for the fourth detection area in the vicinity of the fourth end opposite to the first detection area, and for each line in the third detection area based on the detection result of the black pixel, Detecting a boundary between the non-black pixel and the black pixel continuously arranged in the first direction from the end of the third detection region facing the third end, and For each line in the four detection regions, the lines are continuously aligned in the first direction from the fourth end. Detecting the boundary between the black pixel and the pixel that is not the black pixel, and detecting the third black belt based on the detection result of the boundary for each line in the third detection region; Detecting a fourth black belt based on a detection result of a boundary for each line in the fourth detection region;

  According to one aspect of the present invention, a black belt can be detected from an image. In particular, according to one aspect of the present invention, a black belt can be detected from an image more reliably.

  Embodiments of the present invention will be described below. Correspondences between the constituent elements of the present invention and the embodiments described in the specification or the drawings are exemplified as follows. This description is intended to confirm that the embodiments supporting the present invention are described in the specification or the drawings. Therefore, even if there is an embodiment which is described in the specification or the drawings but is not described here as an embodiment corresponding to the constituent elements of the present invention, that is not the case. It does not mean that the form does not correspond to the constituent requirements. Conversely, even if an embodiment is described here as corresponding to a configuration requirement, that means that the embodiment does not correspond to a configuration requirement other than the configuration requirement. It's not something to do.

  An image processing apparatus according to an aspect of the present invention is a first black image that is located at each of first to fourth edges of an input image and is an area composed of black pixels having a pixel luminance value smaller than a predetermined threshold value. An image processing apparatus (for example, the image processing apparatus 41 in FIG. 2) for detecting each of the band to the fourth black band (for example, the area 11-1 to the area 12-2 in FIG. 1), Black line detection means for detecting a black line that is a line including a predetermined number or more of the black pixels among lines composed of pixels arranged in the first direction (for example, the black line detection unit in FIG. 2). 61) and the first direction from the first end in a first detection region (for example, region 91 in FIG. 4) in the vicinity of the first end based on the detection result of the black line. The black lines continuously arranged in a second direction perpendicular to the The first black belt is detected by detecting a boundary with a line that is not a line, and a second detection region (for example, FIG. 4) in the vicinity of the second end facing the first end. In the area 92), a boundary between the black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection area facing the second end is detected. Thus, the first black band detecting means (for example, the vertical black band coordinate detecting unit 62 in FIG. 2) for detecting the second black band, and the first black band and the second black band from the input image. The third detection region (for example, the region 121 in FIG. 5) in the vicinity of the third end on the image from which the black belt is removed and the first detection region in the vicinity of the fourth end opposite to the third end. Black pixel detection for detecting the black pixels in four detection areas (for example, the area 122 in FIG. 5) The third detection facing the third end for each line in the third detection region based on the stage (for example, the black pixel detection unit 63 in FIG. 2) and the detection result of the black pixel A boundary between the non-black pixel and the black pixel continuously arranged in the first direction from the end of the region is detected, and the fourth line is detected for each line in the fourth detection region. Boundary detection means (for example, the horizontal black belt coordinate detection unit 64 in FIG. 2) that detects a boundary between the black pixels continuously arranged in the first direction from the edge of the pixel and a pixel that is not the black pixel; , Based on the detection result of the boundary for each line in the third detection area, based on the detection result of the boundary for each line in the fourth detection area, and detecting the third black belt, Second black belt detecting means for detecting the fourth black belt (for example, FIG. 2 majority processing section 65).

  The image processing apparatus determines whether or not the input image includes a predetermined number or more of the black lines based on the detection result of the black lines, and the predetermined number or more of the black lines are included. When a black line is included, a determination unit (for example, a black screen determination unit 53 in FIG. 2) that does not include the first black band to the fourth black band is included in the input image. Further, it can be provided.

  The second black belt detecting means determines the position of the third black belt in the input image that has the highest appearance frequency among the positions of the boundaries detected in each line in the third detection region. The position of the boundary is set, and the position with the highest appearance frequency among the positions of the boundary detected in each line in the fourth detection region is set as the position of the boundary of the fourth black belt in the input image. (For example, step S17 in FIG. 3).

  The image processing apparatus includes a detection result of the first black belt to the fourth black belt in the input image and the first black belt to the black in the input image of several frames immediately before the input image. Based on the detection result of the fourth black belt, a determination means for determining the final positions of the first black belt to the fourth black belt of the input image (for example, determination of the black belt coordinates in FIG. 2). A portion 54) can be further provided.

  An image processing method or program according to one aspect of the present invention is a first region that is located at each of the first to fourth ends of an input image, and is a region composed of black pixels whose pixel luminance value is smaller than a predetermined threshold value. Image processing method or program for detecting each of the black belt to the fourth black belt (for example, the area 11-1 to the area 12-2 in FIG. 1), and arranged in a first direction on the input image. Among the lines made up of pixels, a black line that is a line including a predetermined number or more of the black pixels is detected (for example, a black line detection process described with reference to FIG. 6), and the black lines Based on the detection result, in the first detection region in the vicinity of the first end, the black lines continuously arranged from the first end in a second direction perpendicular to the first direction. And the boundary between lines that are not black lines Thus, the first black belt is detected, and the second second region facing the second end in the second detection region in the vicinity of the second end facing the first end. The second black belt is detected by detecting a boundary between a black line and a line that is not continuously arranged in the second direction from the end of the detection region (for example, FIG. The detection process of the upper black belt coordinates described with reference to the detection process of the lower black belt coordinates described with reference to FIG. 8), the first black belt and the second black belt from the input image. For the third detection region in the vicinity of the third end on the removed image and the fourth detection region in the vicinity of the fourth end opposite to the third end, the black pixel is set as a target. (For example, a black pixel detection process described with reference to FIG. 9), and based on the detection result of the black pixel, For each line in the third detection region, pixels that are not the black pixels arranged continuously in the first direction from the end of the third detection region facing the third end; Detecting a boundary with a black pixel, and for each line in the fourth detection region, the black pixels arranged continuously in the first direction from the fourth end and not the black pixels A boundary with a pixel is detected (for example, a left candidate coordinate detection process described with reference to FIG. 10 and a right candidate coordinate detection process described with reference to FIG. 11), and the boundary within the third detection region is detected. The third black band is detected based on the detection result of the boundary for each line, and the fourth black band is detected based on the detection result of the boundary for each line in the fourth detection region. (For example, step S17 of FIG. 3) is included.

  Embodiments to which the present invention is applied will be described below with reference to the drawings.

  First, with reference to FIG. 1, the area | region used as the black belt on an image is demonstrated.

  For example, if an image that is input to the image processing apparatus and is a target for detection of a black belt is referred to as an input image, an effective image that is a content image is displayed in the center area of the input image as shown in FIG. Is done. A black region where no content image is displayed is provided in the region surrounding the effective image, that is, at the end of the input image.

  In FIG. 1, a rectangular area 11-1 is provided at the upper end in the drawing of the input image, and a rectangular area 11-2 is provided at the lower end of the input image. In addition, rectangular regions 12-1 and 12-2 are also provided at the left end and the right end of the input image, respectively. The pixels in these areas 11-1 to 12-2 are black pixels whose luminance value is smaller than a predetermined threshold value except for pixels on which noise is placed, and are composed of these black pixels. The area is called the black belt.

  In particular, in the following, in the figure of the input image, the region 11-1 and the region 11-2 positioned at the upper and lower ends are referred to as vertical black bands, and the region 12-1 and the region positioned at the left and right ends of the input image 12-2 will be referred to as a horizontal black belt. Further, a black pixel whose luminance value is smaller (lower) than a threshold value is called a black pixel.

  Further, hereinafter, the region 11-1 and the region 11-2 are simply referred to as the region 11 when it is not necessary to distinguish between them, and the region 12-1 and the region 12-2 are simply referred to as the region 12 when there is no need to distinguish between them. Called.

  By the way, when an input image is input, the image processing apparatus detects a vertical black band and a horizontal black band from the input image, and information indicating the position of the vertical black band and information indicating the position of the horizontal black band detected as a result. Is output.

  For example, in the figure, the direction from left to right is the x direction, and the direction from top to bottom is the y direction. In the figure of the input image, assuming that the upper left vertex is the origin (reference), a straight line parallel to the x direction is the x axis, and a straight line parallel to the y direction is the y axis, the image processing apparatus is perpendicular to the xy coordinate system. Information indicating the y coordinate of the position of the boundary between the black band and the effective image and the x coordinate of the position of the boundary between the horizontal black band and the effective image are output as information indicating the position of the black band.

  Therefore, the coordinate Yu that is the y coordinate of the lower boundary of the region 11-1, the coordinate Yd that is the y coordinate of the upper boundary of the region 11-2, and the coordinate Xl that is the x coordinate of the right boundary of the region 12-1. , And information indicating the coordinate Xr which is the x coordinate of the left boundary of the region 12-2 is output. In the following, the coordinates Yu, coordinates Yd, coordinates Xl, and coordinates Xr are referred to as upper black belt coordinates Yu, lower black belt coordinates Yd, left black belt coordinates Xl, and right black belt coordinates Xr, respectively.

  An image processing apparatus that detects a black band from an input image and outputs information indicating the position of the black band is configured as shown in FIG. 2, for example. That is, FIG. 2 is a block diagram showing a configuration example of an embodiment of an image processing apparatus to which the present invention is applied.

  The image processing apparatus 41 includes a vertical black band detection unit 51, a horizontal black band detection unit 52, a black screen determination unit 53, and a black band coordinate determination unit 54. The input image input to the image processing device 41 is supplied to the vertical black band detection unit 51 and the horizontal black band detection unit 52.

  The vertical black band detection unit 51 detects a vertical black band from the input image that has been input. The vertical black band detection unit 51 includes a black line detection unit 61 and a vertical black band coordinate detection unit 62.

  The black line detection unit 61 detects a black line that is a line including a predetermined number or more of black pixels from the input image. Here, the line of the input image refers to a column of pixels arranged in the x direction in FIG. The black line detection unit 61 supplies the black line detection result to the vertical black belt coordinate detection unit 62 and the black screen determination unit 53.

  The vertical black belt coordinate detection unit 62 detects the upper black belt coordinate Yu and the lower black belt coordinate Yd on the basis of the detection result of the black line supplied from the black line detection unit 61, and detects those coordinates. Specifically, information indicating these coordinates is supplied to the horizontal black band detection unit 52 and the black band coordinate determination unit 54.

  The horizontal black belt detection unit 52 detects a horizontal black belt from the input image. The horizontal black belt detection unit 52 includes a black pixel detection unit 63, a horizontal black belt coordinate detection unit 64, and a majority processing unit 65. The black pixel detection unit 63 removes the vertical black band from the input image using the upper black band coordinate Yu and the lower black band coordinate Yd supplied from the vertical black band coordinate detection unit 62. Then, the black pixel detection unit 63 detects a black pixel from a predetermined detection region of the input image from which the vertical black band is removed, for example, a region near the left and right ends of the input image in FIG. The result is supplied to the horizontal black belt coordinate detection unit 64.

  Based on the detection result of the black pixel supplied from the black pixel detection unit 63, the horizontal black band coordinate detection unit 64 performs the effective image, the horizontal black band, and the The coordinates indicating the position of the boundary are obtained, and these coordinates are set as the left candidate coordinates which are candidates for the left black belt coordinate Xl. Further, the horizontal black belt coordinate detection unit 64, based on the detection result of the black pixel supplied from the black pixel detection unit 63, for each line in the detection area on the right side of the input image in FIG. The coordinates indicating the position of the boundary with the band are obtained, and those coordinates are set as the right candidate coordinates which are candidates for the right black band coordinate Xr. Then, the horizontal black belt coordinate detection unit 64 supplies the left candidate coordinates and right candidate coordinates for each obtained line, more specifically, information indicating these coordinates to the majority processing unit 65.

  The majority decision processing unit 65 determines the left black belt coordinate Xl and the right black belt coordinate Xr based on the left candidate coordinate and the right candidate coordinate supplied from the horizontal black belt coordinate detection unit 64, and uses these coordinates as the black belt coordinate. It supplies to the determination part 54.

  The black screen determination unit 53 determines whether or not the entire input image is a dark image. That is, the black screen determination unit 53 determines whether or not there are more than a predetermined number of black lines on the input image based on the detection result of the black lines supplied from the black line detection unit 61, and the determination result is The indicated signal is supplied to the black belt coordinate determination unit 54. The black belt coordinate determination unit 54 includes the upper black belt coordinate Yu and the lower black belt coordinate Yd from the vertical black belt coordinate detection unit 62, the left black belt coordinate Xl and the right black belt coordinate Xr from the majority decision processing unit 65, and the black Based on the signal from the screen determination unit 53, the final position of the black belt is determined. That is, the black band coordinate determining unit 54 determines the final upper black band coordinate Yu, lower black band coordinate Yd, left black band coordinate Xl, and right black band coordinate Xr, and determines these coordinates as the position of the black band. Is output as black belt coordinates.

  The black belt coordinates output from the black belt coordinate determination unit 54 are used for processing of displaying an input image from which the black belt region has been removed and generating an interpolation frame of the input image in the subsequent stage.

  Such an image processing apparatus 41 is supplied with a moving image such as a program broadcast on television as an input image. When the input image is supplied, the image processing device 41 starts a black belt coordinate determination process that is a process of detecting a black belt from the input image and outputting the black belt coordinates. Hereinafter, the black belt coordinate determination processing by the image processing device 41 will be described with reference to the flowchart of FIG.

  In step S <b> 11, the black line detection unit 61 performs black line detection processing for detecting a black line from the input image that has been input, and supplies the black line detection result to the vertical black band coordinate detection unit 62 and the black screen determination unit 53. To do. Details of the black line detection process will be described later.

  In step S <b> 12, the vertical black band coordinate detection unit 62 performs upper black band coordinate detection processing based on the black line detection result from the black line detection unit 61 to detect the upper black band coordinate Yu.

  In step S13, the vertical black belt coordinate detection unit 62 performs detection processing of the lower black belt coordinates based on the detection result of the black line from the black line detection unit 61, and detects the lower black belt coordinate Yd. Then, the upper black belt coordinate Yu and the lower black belt coordinate Yd are supplied to the black pixel detection unit 63 and the black belt coordinate determination unit 54.

  For example, as shown in FIG. 4, the vertical black belt coordinate detection unit 62 uses the upper region 91 and the lower region 92 of the input image as detection regions to be detected, and the upper black belt coordinate Yu and the lower region. The black belt coordinate Yd is detected.

  In FIG. 4, an area 91 is an area near the upper end of the input image that is estimated to include a vertical black belt, that is, an area where the y coordinate on the input image is equal to or less than a predetermined Ysu. ing. The vertical black belt coordinate detection unit 62 sequentially determines from the top line in the area 91 whether or not the line is a boundary between the vertical black belt and the effective image, thereby determining the upper black belt. The coordinate Yu is detected. That is, the vertical black band coordinate detection unit 62 detects the boundary between the vertical black band on the upper side of the input image and the effective image.

  The region 92 is a region near the lower end of the input image that is estimated to include a vertical black belt, that is, a region where the y coordinate on the input image is equal to or greater than a predetermined Ysd. Yes. The vertical black band coordinate detection unit 62 starts from the end of the region 92 facing the lower end of the input image, that is, the boundary between the vertical black band and the effective image in order from the uppermost line in the region 92. The lower black belt coordinate Yd is detected by determining whether or not it is. That is, the vertical black belt coordinate detection unit 62 detects the boundary between the vertical black belt on the lower side of the input image and the effective image.

  The details of the upper black belt coordinate detection process and the lower black belt coordinate detection process will be described later.

  Returning to the description of the flowchart of FIG. 3, in step S <b> 14, the black pixel detection unit 63 performs black pixel detection processing and supplies the detection result to the horizontal black belt coordinate detection unit 64. Although details of the black pixel detection process will be described later, in this black pixel detection process, the black pixel detection unit 63 receives the input input image and the upper black band coordinate Yu supplied from the vertical black band coordinate detection unit 62. Based on the lower black belt coordinate Yd, black pixels are detected from a predetermined detection area on the input image.

  In step S15, the horizontal black belt coordinate detection unit 64 performs left candidate coordinate detection processing based on the black pixel detection result from the black pixel detection unit 63, and obtains left candidate coordinates for each line in the detection region. . In step S16, the horizontal black belt coordinate detection unit 64 performs a right candidate coordinate detection process based on the black pixel detection result from the black pixel detection unit 63, and sets the right candidate coordinate for each line in the detection region. Ask. The details of the left candidate coordinate detection process and the right candidate coordinate detection process will be described later.

  For example, the black pixel detection unit 63 removes the vertical black band region from the input image of FIG. 4 based on the upper black band coordinate Yu and the lower black band coordinate Yd supplied from the vertical black band coordinate detection unit 62. Then, black pixels are detected.

  For example, when the vertical black belt region is removed from the input image of FIG. 4, the image shown in FIG. 5 is obtained. The black pixel detection unit 63 detects black pixels using the region 121 near the left end and the region 122 near the right end as detection regions in the figure of the input image from which the vertical black band is removed. That is, the region 121 and the region 122 are regions estimated to include a horizontal black belt, and all the pixels in the region 121 and the region 122 are targeted, and whether or not these pixels are black pixels. Is determined. Here, the area 121 is an area where the x coordinate in the input image from which the vertical black band is removed is Xsl or less, and the area 122 is the x coordinate in the input image from which the vertical black band is removed is greater than or equal to Xsr. It is an area.

  When black pixels are detected in this way, the horizontal black belt coordinate detection unit 64 obtains left candidate coordinates for each line in the region 121 and further obtains right candidate coordinates for each line in the region 122. Here, the line used for the process for obtaining the left candidate coordinates is a line having pixels with the same y coordinate and pixels with x coordinates of 0 to Xsl being arranged. Similarly, the line used for the processing when obtaining the right candidate coordinates is a pixel having the same y coordinate, and the x coordinate is a line formed by arranging pixels from Xsr to the right end coordinate of the input image. The

  When the horizontal black belt coordinate detection unit 64 obtains the left candidate coordinate and the right candidate coordinate for each line, the coordinate is supplied to the majority processing unit 65.

  Returning to the description of the flowchart of FIG. 3, in step S <b> 17, the majority processing unit 65 performs majority processing based on the left candidate coordinates and right candidate coordinates for each line supplied from the horizontal black belt coordinate detection unit 64, and The band coordinate Xl and the right black band coordinate Xr are determined.

  For example, as the majority process, the majority processing unit 65 performs a process of setting the most frequently occurring coordinates among the left candidate coordinates for each line, that is, the most frequently used coordinates as the left black belt coordinates Xl.

  Here, since the x coordinate of the position of the boundary with the effective image of the horizontal black belt is the same in every line, if the boundary is correctly detected, the left candidate coordinates of each line are all the same. Depending on the input image, noise may be applied to the pixel at the boundary of the horizontal black belt, or the pixel of the effective image adjacent to the boundary may be a black pixel. The number of lines should be larger than the number of lines where the boundary could not be detected correctly due to noise or the like. Therefore, the left black belt coordinate Xl can be more reliably specified by setting the leftmost black belt coordinate Xl as the largest coordinate among the left candidate coordinates of each line.

  Further, as in the case of the left black belt coordinate X1, the majority processing unit 65 performs a process of setting the largest number of coordinates among the right candidate coordinates for each line as the right black belt coordinate Xr as the majority processing. Even in this case, the right black belt coordinate Xr can be specified more reliably by setting the most common coordinate as the right black belt coordinate Xr.

  The left black belt coordinate Xl or the right black belt coordinate Xr may be determined by generating a histogram for the left candidate coordinate or the right candidate coordinate and performing predetermined statistical processing, without being limited to the majority process. Further, for example, the average coordinate of the left candidate coordinate or the right candidate coordinate for each line may be set to the left black belt coordinate Xl or the right black belt coordinate Xr.

  After determining the left black belt coordinate Xl and the right black belt coordinate Xr, the majority processing unit 65 supplies these coordinates to the black belt coordinate determination unit 54.

  In step S18, the black screen determination unit 53 determines whether the number of black lines in the entire input image is equal to or greater than a predetermined threshold th1 based on the detection result of the black lines supplied from the black line detection unit 61. Determine whether.

  If it is determined in step S18 that the threshold value is equal to or greater than the threshold th1, that is, if the input image is an overall dark image, in step S19, the black screen determination unit 53 outputs a signal indicating that there is no black band as a black band coordinate. It supplies to the determination part 54.

  That is, when the entire input image is dark, it is difficult to correctly detect the black belt boundary from the input image. Also, since there are many black lines and the entire input image is dark, even if there is a black belt in the input image, it is visually the same as when there is no black belt, and it is considered that there is no black belt in the subsequent stage. Even if processing is performed, there is no particular problem. Therefore, when the entire input image is dark, the black screen determination unit 53 considers that the input image does not have a black band, and a signal that invalidates the coordinates of the detected black band, that is, the black band. A signal indicating the absence is supplied to the black belt coordinate determination unit 54. Thereby, erroneous detection of a black belt can be prevented.

  When a signal indicating that there is no black belt is supplied from the black screen determination unit 53 to the black belt coordinate determination unit 54, the process proceeds to step S21.

  On the other hand, if it is determined in step S18 that the threshold is not equal to or greater than the threshold th1, that is, if the entire input image is not dark, in step S20, the black screen determination unit 53 validates the detected coordinates of the black belt. , That is, a signal indicating that there is a black band is supplied to the black band coordinate determination unit 54.

  When a signal indicating that there is a black band is supplied to the black band coordinate determination unit 54 in step S20, or when a signal indicating that there is no black band is supplied to the black band coordinate determination unit 54 in step S19, in step S21. The black band coordinate determination unit 54 determines and outputs the final black band coordinates, and the black band coordinate determination process ends.

  For example, when a signal indicating that there is no black band is supplied from the black screen determination unit 53, the black band coordinate determination unit 54 invalidates the detected black band coordinate and sets the x and y coordinates of the edge of the input image. Are output as the final black belt coordinates. That is, for example, in the input image of FIG. 1, the upper black belt coordinate Yu is 0, and the lower black belt coordinate Yd is the coordinate of the lower end of the input image. Also, the left black belt coordinate Xl is 0, and the right black belt coordinate Xr is the coordinate of the right end of the input image.

  Further, for example, when a signal indicating that there is a black band is supplied from the black screen determination unit 53, the black band coordinate determination unit 54 includes the upper black band coordinate Yu and the lower black band coordinate Yu supplied from the vertical black band coordinate detection unit 62. The side black belt coordinates Yd, the left black belt coordinates Xl and the right black belt coordinates Xr supplied from the majority processing unit 65 are output as final black belt coordinates.

  When determining the final black band coordinates, the detection result of the black band coordinates with respect to the past input image, that is, the input image of the frame temporally prior to the frame of the input image input this time is used. It may be. That is, the average black belt coordinates in the input image of the predetermined number of frames immediately before, the average coordinates of the newly detected black belt coordinates, and the coordinates with the highest appearance frequency are the final black belt coordinates. Also good. In such a case, for example, the highest number of coordinates among the upper black band coordinates Yu of the predetermined number of immediately preceding frames and the upper black band coordinates Yu supplied from the current vertical black band coordinate detection unit 62 is the final. The upper black belt coordinates Yu are set.

  In this way, by determining the final black belt coordinates using the black belt coordinates of the past frame, it is possible to prevent the position of the black belt coordinates from changing suddenly depending on the frame. In addition, erroneous detection of the black belt coordinates can be prevented, and the black belt can be detected more reliably.

  As described above, the image processing apparatus 41 detects a black line from the input image, and detects a vertical black band using the black line. Further, black pixels are detected from an image obtained by removing the vertical black belt from the input image to detect candidates that become the boundaries of the horizontal black belt, and the horizontal black belt is determined by majority processing using these candidates.

  In this way, by detecting the vertical black band using the black line, that is, by detecting the vertical black band in units of lines, noise is added to the vertical black band, or at the boundary between the vertical black band and the effective image. Even when there are a large number of black pixels, it is possible to eliminate the influence of such noise and the like, and to detect the boundary of the vertical black belt more reliably. Further, by performing majority processing, erroneous detection due to noise can be prevented, and the boundary of the horizontal black belt can be detected more reliably.

  Next, details of each of the processing from step S11 to step S16 in FIG. 3 will be described with reference to the flowcharts in FIGS.

  First, the black line detection process corresponding to the process of step S11 of FIG. 3 will be described with reference to the flowchart of FIG.

  In step S51, the black line detection unit 61 selects one line of the input image that has been input. For example, the black line detection unit 61 sequentially selects from the uppermost line to the lowermost line in the input image of FIG. Here, the line refers to a column of pixels arranged in the x direction, that is, a column of pixels having the same y coordinate.

  In step S52, the black line detection unit 61 selects one pixel constituting the selected line. For example, the black line detection unit 61 sequentially selects from the leftmost pixel to the rightmost pixel constituting the line in FIG. 1, that is, selects pixels included in the line in ascending order of the x coordinate.

  In step S53, the black line detection unit 61 determines whether the luminance value of the selected pixel is smaller than a predetermined threshold th2, that is, whether the pixel is a dark pixel having a low luminance value. If it is determined in step S53 that it is smaller than the threshold th2, in step S54, the black line detection unit 61 sets the vertical black pixel flag to 1 assuming that the pixel is a black pixel, that is, a black pixel.

  Here, the vertical black pixel flag is set for each pixel and indicates whether or not the pixel is a black pixel, and is set to 1 when the pixel is a black pixel, and is set to 0 when the pixel is not a black pixel. Set to

  When the vertical black pixel flag is set in step S54, the process proceeds to step S56. On the other hand, when it is determined in step S53 that it is not smaller than the threshold th2, in step S55, the black line detection unit 61 determines that the selected pixel is not a black pixel and sets the vertical black pixel flag to 0. Set.

  When the vertical black pixel flag is set in step S54 or step S55, in step S56, the black line detection unit 61 accumulates the value of the vertical black pixel flag of the pixel of the selected line.

  That is, the black line detection unit 61 holds the accumulated value of the vertical black pixel flag of the pixels of the line for each line of the input image, and the accumulated value for each line indicates the number of black pixels in each line. ing. The black line detection unit 61 adds the value of the vertical black pixel flag of the pixel set in step S54 or step S55 to the accumulated value of the selected line.

  In step S57, the black line detection unit 61 determines whether or not all the pixels in the selected line have been determined as black pixels, that is, whether or not the comparison with the threshold th2 in step S53 has been performed.

  If it is determined in step S57 that determination has not been performed for all pixels, the process returns to step S52, and the next pixel is selected.

  On the other hand, when it is determined in step S57 that the process has been performed for all the pixels, in step S58, the black line detection unit 61 determines whether or not the cumulative value of the selected line is greater than a predetermined threshold th3. That is, it is determined whether or not a predetermined number or more of black pixels are included in the line.

  If it is determined in step S58 that it is greater than the threshold th3, in step S59, the black line detection unit 61 sets the black line flag to 1, and the process proceeds to step S61. That is, the black line detection unit 61 holds a black line flag indicating whether or not each line of the input image is a black line. Here, the black line flag is set to 1 when the line is a black line, and is set to 0 when the line is not a black line.

  On the other hand, when it is determined in step S58 that it is not larger than the threshold th3, in step S60, the black line detection unit 61 sets the black line flag to 0, assuming that the selected line is not a black line.

  When the black line flag is set in step S59 or step S60, in step S61, the black line detection unit 61 determines whether or not black lines have been determined for all lines of the input image, that is, the threshold th3 in step S58. It is determined whether or not comparison has been performed.

  If it is determined in step S61 that the process has not been performed for all lines, the process returns to step S51, and the next line is selected.

  On the other hand, when it determines with having performed about all the lines in step S61, a process progresses to step S62. In step S62, the black line detection unit 61 supplies the black line flag set for each line of the input image to the vertical black belt coordinate detection unit 62 and the black screen determination unit 53 as the detection result of the black line. The process proceeds to step S12 of step 3. Note that the black line flag supplied to the black screen determination unit 53 is used for determining whether or not the entire input image is dark in the process of step S18 of FIG.

  In this way, the black line detection unit 61 determines, for each line of the input image, whether or not the line is a black line, thereby detecting the black line from the input image and outputting the detection result. .

  Next, an upper black belt coordinate detection process corresponding to the process of step S12 of FIG. 3 will be described with reference to the flowchart of FIG.

  In step S91, the vertical black belt coordinate detection unit 62 selects one line in the detection area with the area 91 in FIG. 4 as the detection area. For example, the vertical black belt coordinate detection unit 62 sequentially selects the lines in the area 91 of FIG. 4 from the uppermost line to the lower line in the drawing.

  Here, the region 91 is a region estimated to include a vertical black belt boundary. That is, since the boundary of the vertical black belt is not located near the center of the input image, the region 91 in FIG. 4 where the upper vertical black belt boundary can exist is set as the detection region to be detected. The upper black belt coordinate Yu can be detected more efficiently.

  In step S92, the vertical black belt coordinate detection unit 62 determines whether the selected line is a black line based on the black line flag supplied from the black line detection unit 61. For example, when 1 is set in the black line flag, it is determined that the selected line is a black line.

  If it is determined in step S92 that the line is not a black line, in step S93, the vertical black band coordinate detection unit 62 sets the position of the line immediately before the currently selected line as the upper black band coordinate Yu, and the process is performed. Proceed to step S13 in FIG.

  That is, at the boundary of the vertical black belt in the region 91 of FIG. 4, the lowermost line of the vertical black belt is a black line, and the uppermost line of the effective image is not a black line. Therefore, if the lines in the area 91 are selected in order from the upper line, all the lines in the vertical black belt should be black lines, so the first non-black line that appears first is the uppermost line of the effective image. Should be the line. Therefore, the vertical black belt coordinate detection unit 62 sets the y coordinate of the position of the line selected immediately before the first non-black line as the upper black belt coordinate Yu. That is, the vertical black belt coordinate detection unit 62 detects a boundary between a black line continuously arranged downward from the upper end of the input image and a line that is not a black line.

  On the other hand, if it is determined in step S92 that the line is a black line, in step S94, the vertical black belt coordinate detection unit 62 determines whether the line next to the selected line is a line in the detection area. Determine.

  If it is determined in step S94 that the line is within the detection area, the process returns to step S91, and the next line is selected.

  On the other hand, if it is determined in step S94 that the line is not within the detection area, that is, if the line is outside the detection area, the boundary of the vertical black belt is not detected within the detection area. Proceed to S95.

  In step S95, the vertical black belt coordinate detection unit 62 has detected no vertical black belt on the upper side of the input image in FIG. 4, so that the processing is performed with the position of the upper edge of the input image as the upper black belt coordinate Yu. The process proceeds to step S13 of step 3.

  In this way, the vertical black belt coordinate detection unit 62 determines whether each detection line is a black line for the detection area, and continuously continues downward from the upper end of the area 91 in FIG. The boundary between the vertical black belt and the effective image is detected by detecting the boundary between the black lines that are lined up and the line that is not a black line. Thus, by determining whether or not each line is a black line and detecting the boundary of the vertical black belt, the position of the vertical black belt boundary can be detected more reliably.

  In the past, the luminance value of one pixel was compared with a threshold value to detect the position of the black belt boundary, so noise was applied to the pixel to be compared, or the pixel was on the effective image. In the case of a black pixel, the border of the black belt could not be detected correctly.

  On the other hand, the vertical black belt coordinate detection unit 62 determines whether each line is a black line and detects the boundary of the vertical black belt. In the image processing device 41, even if a pixel forming a black line includes a pixel with noise, if the number of black pixels is larger than the threshold th3, the line is correctly a black line. It is said. Further, even if black pixels exist in a part of the line of the effective image, if the number of black pixels is equal to or less than the threshold th3, the line is not regarded as a black line.

  Therefore, by determining whether each line is a black line and detecting the border of the vertical black band, it is more reliable regardless of the influence of noise or whether there is a black part at the edge of the effective image. It is possible to detect the border of the vertical black belt. That is, the influence of noise or the like can be eliminated by detecting the boundary of the vertical black belt in units of lines, and the detection accuracy can be improved.

  FIG. 8 is a flowchart for explaining the detection process of the lower black belt coordinates corresponding to the process of step S13 of FIG. Hereinafter, the detection process of the lower black belt coordinates will be described with reference to the flowchart of FIG.

  In step S121, the vertical black belt coordinate detection unit 62 selects one line in the detection area with the area 92 in FIG. 4 as the detection area. For example, the vertical black belt coordinate detection unit 62 sequentially selects the lines in the region 92 of FIG. 4 from the uppermost line to the lower line in the drawing.

  Here, the region 92 is assumed to include the boundary of the vertical black belt, and similarly to the case of the region 91, the region 92 where the boundary of the vertical black belt may exist is a detection region to be detected. By doing so, the lower black belt coordinate Yd can be detected more efficiently.

  In step S122, the vertical black belt coordinate detection unit 62 determines whether the selected line is a black line based on the black line flag supplied from the black line detection unit 61.

  If it is determined in step S122 that the line is a black line, in step S123, the vertical black band coordinate detection unit 62 sets the position of the currently selected line as the lower black band coordinate Yd. Then, the vertical black belt coordinate detection unit 62 supplies the lower black belt coordinate Yd and the upper black belt coordinate Yu detected in the process of step S12 of FIG. 3 to the black pixel detection unit 63 and the black belt coordinate determination unit 54. Then, the process proceeds to step S14 in FIG.

  That is, at the boundary of the vertical black belt in the region 92 of FIG. 4, the uppermost line of the vertical black belt is a black line, and the lowermost line of the effective image is not a black line. Therefore, when the lines in the region 92 are selected in order from the upper line, the lines in the effective image are not black lines, and lines that are not black lines should be continuously arranged. The black line that appears first should be the uppermost line of the vertical black belt. Therefore, the vertical black belt coordinate detection unit 62 sets the y coordinate of the position of the black line that appears first as the lower black belt coordinate Yd. That is, the vertical black belt coordinate detection unit 62 detects a boundary between a black line and a line that is not a continuous black line.

  On the other hand, if it is determined in step S122 that the line is not a black line, in step S124, the vertical black belt coordinate detection unit 62 determines whether or not the selected line is the last line.

  If it is determined in step S124 that the line is not the last line, there is a line that has not yet been processed in the detection area, so the process returns to step S121, and the next line is selected.

  On the other hand, if it is determined in step S124 that the line is the last line, the vertical black belt boundary has not been detected in the detection area, and the process proceeds to step S125.

  In step S125, the vertical black belt coordinate detection unit 62 does not detect the vertical black belt on the lower side of the input image in FIG. 4, and therefore, the position of the lower edge of the input image is set as the lower black belt coordinate Yd. . Then, the vertical black belt coordinate detection unit 62 supplies the lower black belt coordinate Yd and the upper black belt coordinate Yu detected in the process of step S12 of FIG. 3 to the black pixel detection unit 63 and the black belt coordinate determination unit 54. Then, the process proceeds to step S14 in FIG.

  In this way, the vertical black belt coordinate detection unit 62 determines whether each detection line is a black line for the detection area, and moves downward from the end of the area 92 facing the lower end of the input image. The boundary between the vertical black belt and the effective image is detected by detecting the boundary between the black line and the line that is not a continuous black line. Thus, by determining whether or not each line is a black line and detecting the boundary of the vertical black belt, the position of the vertical black belt boundary can be detected more reliably.

  Next, the black pixel detection process corresponding to the process of step S14 of FIG. 3 will be described with reference to the flowchart of FIG.

  In step S151, the black pixel detection unit 63 removes the vertical black belt from the input image using the upper black belt coordinate Yu and the lower black belt coordinate Yd supplied from the vertical black belt coordinate detection unit 62. To do. Thereby, for example, the image shown in FIG. 5 is obtained.

  In this way, the detection of the horizontal black band is performed for a predetermined area on the input image from which the vertical black band has been removed. In this way, by setting a predetermined area on the input image from which the vertical black band has been removed as a target for detection of the horizontal black band, an area where no horizontal black band exists is excluded from the detection target area. It is possible to detect a horizontal black belt more reliably and quickly.

  In step S152, the black pixel detection unit 63 sets the pixels in the detection region as 1 by using the regions near the left and right edges of the input image from which the vertical black band in FIG. Select one.

  In step S153, the black pixel detection unit 63 determines whether the luminance value of the selected pixel is smaller than a predetermined threshold th2. Here, the threshold th2 is the same value as the threshold th2 in the process of step S53 of FIG.

  If it is determined in step S153 that it is smaller than the threshold th2, in step S154, the black pixel detection unit 63 sets the horizontal black pixel flag to 1 assuming that the pixel is a black pixel, that is, a black pixel.

  Here, the horizontal black pixel flag is set for each pixel and indicates whether or not the pixel is a black pixel. If the pixel is a black pixel, the flag is set to 1. If the pixel is not a black pixel, the horizontal black pixel flag is set. Set to zero.

  If the horizontal black pixel flag is set in step S154, the process proceeds to step S156. On the other hand, if it is determined in step S153 that it is not smaller than the threshold th2, the black pixel detection unit 63 sets the horizontal black pixel flag to 0 in step S155, assuming that the selected pixel is not a black pixel. Set.

  When the horizontal black pixel flag is set in step S154 or step S155, in step S156, the black pixel detection unit 63 determines whether or not black pixels have been determined for all pixels in the detection area, that is, the threshold value in step S153. It is determined whether or not a comparison with th2 has been performed.

  If it is determined in step S156 that determination has not been performed for all pixels, the process returns to step S152, and the next pixel is selected.

  On the other hand, when it is determined in step S156 that all pixels have been used, the black pixel detection unit 63 detects the horizontal black band coordinates as the black pixel detection result using the horizontal black pixel flag for each pixel in the detection area. The process proceeds to step S15 in FIG.

  In this way, the black pixel detection unit 63 detects black pixels from the detection area using the areas 121 and 122 in FIG. 5 as detection areas. The detection result of the black pixel is used in the horizontal black belt coordinate detection unit 64 for the left candidate coordinate detection process for detecting the left candidate coordinate and the right candidate coordinate detection process for detecting the right candidate coordinate.

  The left candidate coordinate detection process corresponding to the process of step S15 of FIG. 3 will be described below with reference to the flowchart of FIG.

  In step S181, the horizontal black band coordinate detection unit 64 selects one line in the area 121 using the area 121 of the input image from which the vertical black band in FIG. 5 is removed as a detection area. For example, the horizontal black belt coordinate detection unit 64 sequentially selects from the uppermost line to the lower line in the diagram of the region 121 of FIG. Here, the line refers to a column of pixels in the region 121 arranged in the x direction, that is, a column of pixels in the region 121 having the same y coordinate.

  In step S182, the horizontal black belt coordinate detection unit 64 selects one pixel constituting the selected line. For example, the horizontal black belt coordinate detection unit 64 sequentially selects from the leftmost pixel to the rightmost pixel constituting the line in FIG. 5, that is, selects pixels included in the line in ascending order of the x coordinate.

  Here, the horizontal black belt coordinate detection unit 64 determines whether or not these pixels are black pixels in order from the leftmost pixel to the right pixel in FIG. 5 for the selected line. In the area 121, the horizontal black band should be located in the left area in the area 121. Therefore, all the selected pixels are black pixels up to the rightmost pixel of the horizontal black band, and the effective image is displayed. From the leftmost pixel to the rightmost pixel of the region 121, it is highly possible that the selected pixel will not be a black pixel.

  Therefore, the horizontal black belt coordinate detection unit 64 determines whether or not the pixel is a black pixel in order from the pixel on the left side of the line, and selects a pixel before that pixel when a pixel that is not a black pixel appears. The x coordinate of the pixel position is stored as a temporary left candidate coordinate. The pixel at this held position is highly likely to be the rightmost pixel of the horizontal black belt.

  Then, when a black pixel appears again after that, the pixel at the held position may be a noisy pixel in the horizontal black belt. Discard the temporary left candidate coordinates that were held. That is, the horizontal black belt coordinate detection unit 64 cancels the holding of the temporary left candidate coordinate. Further, when a pixel that is not a black pixel appears again, the horizontal black belt coordinate detection unit 64 holds the x coordinate of the position of the pixel selected immediately before that pixel as a temporary left candidate coordinate, and finally holds it. The left coordinate is the left candidate coordinate of the line. In other words, the horizontal black belt coordinate detection unit 64 has a boundary between a black pixel and a pixel that is not a black pixel that is continuously arranged in the left direction from the right end of the region 121 facing the left end of the input image. And the position of the black pixel at the boundary is set as the left candidate coordinate. Therefore, the position of the black pixel located on the rightmost side on the line is set as the left candidate coordinate of the line.

  In such a case, the position of the boundary between the horizontal black belt and the effective image can be reliably detected even if a pixel with noise is included in the horizontal black belt portion on the line. In addition, if a black pixel is included in the effective image portion on the line, the pixel located on the rightmost side on the effective image among those pixels is set as the left candidate coordinate, In comparison, since the number of lines that include black pixels in the effective image is mostly small, the position of the boundary of the horizontal black belt can be detected correctly by the majority process described above.

  When a pixel is selected in step S182, in step S183, the horizontal black belt coordinate detection unit 64 determines whether the selected pixel is a black pixel based on the horizontal black pixel flag supplied from the black pixel detection unit 63. Determine whether. For example, when 1 is set in the horizontal black pixel flag of the selected pixel, it is determined that the pixel is a black pixel.

  If it is determined in step S183 that the pixel is not a black pixel, in step S184, the horizontal black belt coordinate detection unit 64 determines whether or not the temporary left candidate coordinate is held.

  If it is determined in step S184 that the data is held, the process in step S185 is skipped, and the process proceeds to step S188.

  On the other hand, when it is determined in step S184 that it is not held, in step S185, the horizontal black belt coordinate detection unit 64 determines the position of the pixel selected immediately before the currently selected pixel as follows. Stored as temporary left candidate coordinates. When the provisional left candidate coordinates are held by the horizontal black belt coordinate detection unit 64, the process proceeds to step S188.

  When it is determined in step S183 that the selected pixel is a black pixel, in step S186, the horizontal black belt coordinate detection unit 64 determines whether or not the temporary left candidate coordinate is held.

  If it is determined in step S186 that the temporary left candidate coordinates are not held, the process of step S187 is skipped, and the process proceeds to step S188.

  On the other hand, when it is determined in step S186 that the temporary left candidate coordinates are held, in step S187, the horizontal black belt coordinate detection unit 64 discards the temporary left candidate coordinates held. . When the temporary left candidate coordinates are discarded, the process proceeds to step S188.

  When the temporary left candidate coordinates are discarded at step S187, when it is determined at step S186 that the temporary left candidate coordinates are not retained, when the temporary left candidate coordinates are retained at step S185, or step S184. If it is determined that the temporary left candidate coordinates are held, the process proceeds to step S188.

  In step S188, the horizontal black belt coordinate detection unit 64 determines whether or not the selected pixel is the last pixel of the selected line, that is, the rightmost pixel on the line in FIG.

  If it is determined in step S188 that the pixel is not the last pixel, since there is a pixel that has not been selected on the selected line, the process returns to step S182, and the next pixel is selected.

  On the other hand, if it is determined in step S188 that the pixel is the last pixel, it is determined whether or not all the pixels on the selected line are black pixels, and thus the process proceeds to step S189. In step S189, the horizontal black belt coordinate detection unit 64 determines the final left candidate coordinates of the selected line.

  For example, when the horizontal black belt coordinate detection unit 64 holds a temporary left candidate coordinate, the horizontal black belt coordinate detection unit 64 sets the held left candidate coordinate as the final left candidate coordinate of the selected line. Further, for example, if the horizontal black belt coordinate detection unit 64 does not hold the temporary left candidate coordinates, it is determined that the horizontal black belt cannot be detected, and the line that selects the coordinate at the left end of the region 121 in FIG. 5 is selected. The left candidate coordinates of.

  In step S190, the horizontal black belt coordinate detection unit 64 determines whether or not the left candidate coordinates have been determined for all the lines in the area 121 that is the detection area. If it is determined in step S190 that the left candidate coordinates have not yet been determined for all lines, the process returns to step S181, and the next line is selected.

  In contrast, if it is determined in step S190 that the left candidate coordinates have been determined for all lines, the process proceeds to step S16 in FIG.

  In this way, the horizontal black belt coordinate detection unit 64 determines the left candidate coordinates for each line of the region 121 that is set as the detection region. In this way, by determining the left candidate coordinates for each line, in the subsequent majority process, the boundary of the horizontal black belt is more reliably determined regardless of the influence of noise or whether there is a black portion at the edge of the effective image. Can be detected.

  Next, the right candidate coordinate detection process corresponding to the process of step S16 of FIG. 3 will be described with reference to the flowchart of FIG.

  In step S221, the horizontal black belt coordinate detection unit 64 selects one line in the region 122 using the input image region 122 from which the vertical black belt in FIG. 5 is removed as a detection region. For example, the horizontal black belt coordinate detecting unit 64 sequentially selects from the uppermost line to the lower line in the region 122 of FIG. Here, the line means a column of pixels in the region 122 arranged in the x direction, that is, a column of pixels in the region 122 having the same y coordinate.

  In step S222, the horizontal black belt coordinate detection unit 64 selects one pixel constituting the selected line. For example, the horizontal black belt coordinate detection unit 64 sequentially selects from the leftmost pixel to the rightmost pixel constituting the line in FIG. 5, that is, selects pixels included in the line in ascending order of the x coordinate.

  Here, the horizontal black belt coordinate detection unit 64 determines whether or not these pixels are black pixels in order from the leftmost pixel to the right pixel in FIG. 5 for the selected line. In the region 122, the horizontal black belt should be located in the right region in the region 122. Therefore, all the selected pixels are black pixels from the leftmost pixel to the rightmost pixel of the horizontal black belt. Should be.

  Therefore, the horizontal black belt coordinate detection unit 64 determines whether or not the pixel is a black pixel in order from the pixel on the left side of the line, and when the black pixel appears, the x coordinate of the position of the pixel is temporarily calculated. Is stored as the right candidate coordinates. The pixel at this held position is highly likely to be the leftmost pixel of the horizontal black belt.

  After that, when a pixel that is not a black pixel appears, the pixel is a pixel with noise in the horizontal black band, or the pixel at the position held is a black pixel in the effective image. Therefore, the horizontal black belt coordinate detection unit 64 discards the temporary right candidate coordinates that are held. Further, when a black pixel appears again, the horizontal black band coordinate detection unit 64 holds the x coordinate of the position of the black pixel as a temporary right candidate coordinate, and the last held coordinate is the right candidate for the line. It is a coordinate. In other words, the horizontal black belt coordinate detection unit 64 detects a boundary between a black pixel that is continuously arranged in the left direction from the right end of the input image and a pixel that is not a black pixel, and the black pixel at the boundary. Is the right candidate coordinate. Therefore, the position of the leftmost black pixel among the black pixels continuously arranged from the right end of the line is set as the right candidate coordinate of the line.

  In such a case, if the horizontal black belt part on the line includes a pixel with noise, that is, a pixel that is not a black pixel, the position of the black pixel adjacent to the right side of the pixel becomes the right candidate coordinate, The position of the horizontal black border cannot be detected correctly. However, since the number of lines in which noisy pixels are included in the horizontal black belt portion is almost smaller than the total number of lines, the majority process described above eventually results in the boundary of the horizontal black belt. Can be detected correctly.

  When a pixel is selected in step S222, in step S223, the horizontal black belt coordinate detection unit 64 determines whether the selected pixel is a black pixel based on the horizontal black pixel flag supplied from the black pixel detection unit 63. Determine whether.

  If it is determined in step S223 that the pixel is a black pixel, in step S224, the horizontal black belt coordinate detection unit 64 determines whether or not the temporary right candidate coordinate is held.

  If it is determined in step S224 that the data is held, the process in step S225 is skipped, and the process proceeds to step S228.

  On the other hand, if it is determined in step S224 that it is not held, in step S225, the horizontal black belt coordinate detection unit 64 holds the position of the currently selected pixel as a temporary right candidate coordinate. . If the temporary right candidate coordinates are held by the horizontal black belt coordinate detection unit 64, the process proceeds to step S228.

  If it is determined in step S223 that the selected pixel is not a black pixel, in step S226, the horizontal black belt coordinate detection unit 64 determines whether or not a temporary right candidate coordinate is held.

  If it is determined in step S226 that the temporary right candidate coordinates are not held, the process of step S227 is skipped, and the process proceeds to step S228.

  On the other hand, when it is determined in step S226 that the temporary right candidate coordinates are held, in step S227, the horizontal black belt coordinate detection unit 64 discards the held temporary right candidate coordinates. . When the temporary right candidate coordinates are discarded, the process proceeds to step S228.

  When the temporary right candidate coordinates are discarded at step S227, when it is determined at step S226 that the temporary right candidate coordinates are not retained, when the temporary right candidate coordinates are retained at step S225, or step S224. If it is determined in step S228 that the temporary right candidate coordinates are held, the process proceeds to step S228.

  In step S228, the horizontal black belt coordinate detection unit 64 determines whether or not the selected pixel is the last pixel of the selected line, that is, the rightmost pixel on the line in FIG.

  If it is determined in step S228 that the pixel is not the last pixel, there is a pixel that has not yet been selected on the selected line, so the process returns to step S222, and the next pixel is selected.

  On the other hand, if it is determined in step S228 that the pixel is the last pixel, it is determined whether or not all the pixels on the selected line are black pixels, and thus the process proceeds to step S229. In step S229, the horizontal black belt coordinate detection unit 64 determines final right candidate coordinates of the selected line.

  For example, when the horizontal black belt coordinate detection unit 64 holds a temporary right candidate coordinate, the horizontal black belt coordinate detection unit 64 sets the held right right candidate coordinate as the final right candidate coordinate of the selected line. Further, for example, when the horizontal black belt coordinate detection unit 64 does not hold the temporary right candidate coordinates, the horizontal black belt coordinate detection unit 64 selects the right end coordinate of the region 122 in FIG. The right-hand candidate coordinates of the line.

  In step S230, the horizontal black belt coordinate detection unit 64 determines whether or not the right candidate coordinates have been determined for all the lines in the area 122 that is the detection area. If it is determined in step S230 that the right candidate coordinates have not yet been determined for all lines, the process returns to step S221, and the next line is selected.

  On the other hand, if it is determined in step S230 that the right candidate coordinates have been determined for all the lines, the horizontal black belt coordinate detection unit 64 determines the right candidate coordinates for each determined line and the step S15 in FIG. The left candidate coordinates for each line determined in the processing are supplied to the majority processing unit 65. When the right candidate coordinates and the left candidate coordinates are supplied to the majority processing unit 65, the process proceeds to step S17 in FIG.

  In this way, the horizontal black belt coordinate detection unit 64 determines the right candidate coordinates for each line of the region 122 that is the detection region. In this way, by determining the right candidate coordinates for each line, in the subsequent majority process, the border of the horizontal black belt is more reliably determined regardless of the influence of noise or whether there is a black portion at the edge of the effective image. Can be detected.

  As described above, by detecting the vertical black band in units of lines, the position of the boundary of the vertical black band can be detected more reliably regardless of the influence of noise or whether there is a black part at the edge of the effective image. can do. Further, by detecting the left candidate coordinates and the right candidate coordinates and performing majority processing using these coordinates, it is possible to prevent erroneous detection due to noise and more reliably detect the position of the boundary of the horizontal black belt. .

  The series of processes described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software may execute various functions by installing a computer incorporated in dedicated hardware or various programs. For example, it is installed from a program recording medium in a general-purpose personal computer or the like.

  FIG. 12 is a block diagram illustrating a hardware configuration example of a computer that executes the above-described series of processing by a program.

  In a computer, a central processing unit (CPU) 201, a read only memory (ROM) 202, and a random access memory (RAM) 203 are connected to each other by a bus 204.

  An input / output interface 205 is further connected to the bus 204. The input / output interface 205 includes an input unit 206 including a keyboard, a mouse, and a microphone, an output unit 207 including a display and a speaker, a recording unit 208 including a hard disk and nonvolatile memory, and a communication unit 209 including a network interface. A drive 210 for driving a removable medium 211 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory is connected.

  In the computer configured as described above, the CPU 201 loads, for example, the program recorded in the recording unit 208 to the RAM 203 via the input / output interface 205 and the bus 204, and executes the program. Is performed.

  The program executed by the computer (CPU 201) is, for example, a magnetic disk (including a flexible disk), an optical disk (CD-ROM (Compact Disc-Read Only Memory), DVD (Digital Versatile Disc), etc.), a magneto-optical disk, or a semiconductor. The program is recorded on a removable medium 211 that is a package medium including a memory or the like, or provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

  The program can be installed in the recording unit 208 via the input / output interface 205 by attaching the removable medium 211 to the drive 210. Further, the program can be received by the communication unit 209 via a wired or wireless transmission medium and installed in the recording unit 208. In addition, the program can be installed in the ROM 202 or the recording unit 208 in advance.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  The embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

It is a figure for demonstrating a black belt. It is a block diagram which shows the structural example of one Embodiment of the image processing apparatus to which this invention is applied. It is a flowchart explaining a black belt coordinate determination process. It is a figure explaining the detection of a vertical black belt. It is a figure explaining the left candidate coordinate and right candidate coordinate of a horizontal black belt. It is a flowchart explaining a black line detection process. It is a flowchart explaining the detection process of an upper black belt coordinate. It is a flowchart explaining the detection process of a lower black belt coordinate. It is a flowchart explaining a black pixel detection process. It is a flowchart explaining the detection process of a left candidate coordinate. It is a flowchart explaining the detection process of a right candidate coordinate. It is a block diagram which shows the structural example of a computer.

Explanation of symbols

  41 image processing device, 51 vertical black band coordinate detection unit, 52 horizontal black band coordinate detection unit, 53 black screen determination unit, 54 black band coordinate determination unit, 61 black line detection unit, 62 vertical black band coordinate detection unit, 63 black Pixel detection unit, 64 horizontal black belt coordinate detection unit, 65 majority processing unit

Claims (6)

Detecting each of the first black band to the fourth black band that is located at each of the first end to the fourth end of the input image and is an area composed of black pixels whose pixel luminance value is smaller than a predetermined threshold value. An image processing apparatus that
A black line detecting means for detecting a black line which is a line including a predetermined number or more of the black pixels among lines formed of pixels arranged in a first direction on the input image;
Based on the detection result of the black line, the first detection region in the vicinity of the first end is continuously arranged from the first end in a second direction perpendicular to the first direction. In addition, by detecting a boundary between the black line and a line that is not a black line, the first black belt is detected, and a second in the vicinity of the second end facing the first end is detected. Detecting a boundary between a black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection area facing the second end in the detection area; And first black belt detecting means for detecting the second black belt,
A third detection region in the vicinity of the third end on the image obtained by removing the first black belt and the second black belt from the input image, and the fourth detection region facing the third end. Black pixel detection means for detecting the black pixel for a fourth detection region in the vicinity of the edge;
Based on the detection result of the black pixel, each line in the third detection region is continuously arranged in the first direction from the end of the third detection region facing the third end. In addition, the boundary between the pixel that is not the black pixel and the black pixel is detected, and each line in the fourth detection region is continuously arranged in the first direction from the fourth end. Boundary detection means for detecting a boundary between the black pixel and the pixel that is not the black pixel;
Based on the detection result of the boundary for each line in the third detection region, the third black belt is detected, and based on the detection result of the boundary for each line in the fourth detection region, An image processing apparatus comprising: second black belt detection means for detecting a fourth black belt. Based on the detection result of the black line, it is determined whether or not the input image includes a predetermined number or more of the black lines, and the predetermined number or more of the black lines are included. The image processing apparatus according to claim 1, further comprising: a determination unit that determines that the first black band to the fourth black band are not included in the input image when the input image is included. The second black belt detection means sets a position having the highest appearance frequency among the positions of the boundaries detected in each line in the third detection region as the boundary of the third black belt in the input image. The position of the highest appearance frequency among the positions of the boundaries detected in each line in the fourth detection region is set as the position of the boundary of the fourth black belt in the input image. The image processing apparatus according to 1. Detection results of the first black belt to the fourth black belt in the input image and the first black belt to the fourth black belt in the input image of several frames immediately before the input image. The image processing apparatus according to claim 1, further comprising: a determining unit that determines a final position of the first black band to the fourth black band of the input image based on a detection result. Detecting each of the first black band to the fourth black band that is located at each of the first end to the fourth end of the input image and is an area composed of black pixels whose pixel luminance value is smaller than a predetermined threshold value. An image processing method for
Detecting a black line that is a line including a predetermined number or more of the black pixels, among lines formed of pixels arranged in a first direction on the input image;
Based on the detection result of the black line, the first detection region in the vicinity of the first end is continuously arranged from the first end in a second direction perpendicular to the first direction. In addition, by detecting a boundary between the black line and a line that is not a black line, the first black belt is detected, and a second in the vicinity of the second end facing the first end is detected. Detecting a boundary between a black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection area facing the second end in the detection area; And detecting the second black belt,
A third detection region in the vicinity of the third end on the image obtained by removing the first black belt and the second black belt from the input image, and the fourth detection region facing the third end. For the fourth detection region in the vicinity of the end, the black pixel is detected,
Based on the detection result of the black pixel, each line in the third detection region is continuously arranged in the first direction from the end of the third detection region facing the third end. In addition, the boundary between the pixel that is not the black pixel and the black pixel is detected, and each line in the fourth detection region is continuously arranged in the first direction from the fourth end. Detecting a boundary between the black pixel and the non-black pixel;
Based on the detection result of the boundary for each line in the third detection region, the third black belt is detected, and based on the detection result of the boundary for each line in the fourth detection region, An image processing method including a step of detecting a fourth black belt. Detecting each of the first black band to the fourth black band that is located at each of the first end to the fourth end of the input image and is an area composed of black pixels whose pixel luminance value is smaller than a predetermined threshold value. A program for image processing,
Detecting a black line that is a line including a predetermined number or more of the black pixels, among lines formed of pixels arranged in a first direction on the input image;
Based on the detection result of the black line, the first detection region in the vicinity of the first end is continuously arranged from the first end in a second direction perpendicular to the first direction. In addition, by detecting a boundary between the black line and a line that is not a black line, the first black belt is detected, and a second in the vicinity of the second end facing the first end is detected. Detecting a boundary between a black line and a line that is not a black line continuously arranged in the second direction from the end of the second detection area facing the second end in the detection area; And detecting the second black belt,
A third detection region in the vicinity of the third end on the image obtained by removing the first black belt and the second black belt from the input image, and the fourth detection region facing the third end. For the fourth detection region in the vicinity of the end, the black pixel is detected,
Based on the detection result of the black pixel, each line in the third detection region is continuously arranged in the first direction from the end of the third detection region facing the third end. In addition, the boundary between the pixel that is not the black pixel and the black pixel is detected, and each line in the fourth detection region is continuously arranged in the first direction from the fourth end. Detecting a boundary between the black pixel and the non-black pixel;
Based on the detection result of the boundary for each line in the third detection region, the third black belt is detected, and based on the detection result of the boundary for each line in the fourth detection region, A program for causing a computer to execute a step of detecting a fourth black belt.

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