JP4871820B2 - Video display system and parameter generation method for the system - Google Patents

Description

  The present invention relates to a video display system and a parameter generation method of the system, and more particularly to a video display system that obtains a desired video by performing geometric correction on an input video and displaying the same, and parameter generation of the system Regarding the method.

As a conventional technique for displaying an input video photographed using a fisheye lens or the like using a plurality of image projection apparatuses, for example, a technique described in Patent Document 1 is known. In this conventional technique, an area to be actually displayed is cut out from an input video based on an input geometric profile and an output geometric profile, and the cut video is subjected to geometric correction and projected, thereby degrading video quality. In this way, a desired image can be obtained on a screen.
JP 2005-347813 A

  In the conventional technology described above, the display area clipping process must be performed as a resampling process. Therefore, the clipping process cannot be performed with an inexpensive apparatus having a simple configuration such as a scan converter. Has the problem of increasing

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to display an image captured using a fisheye lens or the like at a lower cost while suppressing deterioration in image quality and the system. It is to provide a parameter generation method.

  According to the present invention, the object is to cut out a rectangular region that forms a part of the input image based on the extraction parameter, an image supply unit that supplies an input image that is an image generated under conditions based on imaging parameters, An image cutout unit that outputs as a cutout image, a correction unit that performs geometric correction on the cutout image based on a geometric correction parameter, and a display unit that displays an image output by the correction unit The geometric correction parameter is a correction parameter such that a desired image can be obtained on the display unit when an image generated based on a projection parameter based on a design value of the display unit is corrected and output. 1 correction parameter, an image generated based on the imaging parameter and the extraction parameter, and generated based on the projection parameter Is accomplished by being a correction parameter second combines the correction parameter is a correction parameter for correcting the difference between the image.

  That is, the present invention does not attempt to maintain video quality by a complicated clipping process as in the technique described in Patent Document 1 for a high-resolution input image, and the process performed by the clipping unit is a rectangular area. By simply performing extraction and resolution conversion, and performing a complicated geometric correction process at the same time in the correction unit, deterioration of video quality is suppressed.

  According to the present invention, it is possible to display an image captured using a fisheye lens or the like as a desired image at a lower cost as compared with the prior art while suppressing deterioration in image quality.

  Embodiments of a video display system and a parameter generation method of the system according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a video display system according to the first embodiment of the present invention. The video display system according to this embodiment includes an image supply unit 101, cropping units 112 and 122, correction units 113 and 123, projection units 114 and 124, and a screen 105.

  The image supply unit 101 supplies an image captured by the equidistant fisheye lens to the clipping units 112 and 122 from time to time. For example, the image supply unit 101 includes a pair of a high-vision camera with an equidistant fisheye lens and a video distributor. Is done.

  The cutout units 112 and 122 cut out a part of the region including the region to be projected on the screen 105 from the image supplied by the image supply unit 101, perform resolution conversion, and output to the correction units 113 and 123. Yes, for example, a scan converter. The detailed configuration will be described later with reference to FIG.

  The correction units 113 and 123 perform geometric correction processing and pixel value conversion processing on the images input from the clipping units 112 and 122, and then supply the images to the projection units 114 and 124, thereby projecting 2 on the screen 105. The two images are smoothly connected to be viewed as one desired image. The detailed configuration will be described later with reference to FIG.

  The projection units 114 and 124 project the images input from the correction units 113 and 123 onto the screen 105, and adjacent projection areas are formed so that each video can form one video on the screen 105. They are arranged so as to partially overlap each other. A specific example of the projection units 114 and 124 is a liquid crystal projector, for example.

  As the screen 105, for example, a front projection screen having a hemispherical shape that is concave as viewed from the viewer is used. This makes it possible to correctly display an image taken using an equidistant fisheye lens so as to efficiently cover a wide portion of the viewer's field of view.

  In the embodiment of the present invention described below, a configuration including a cutout unit, a correction unit, and a projection unit is referred to as a “display sequence”. Although the video display system in the example shown in FIG. 1 is shown as having two display sequences, the present invention does not have to limit the number of display sequences to two, and the channels output by the image supply unit 101 It can be increased or decreased by increasing or decreasing the number.

  FIG. 2 is a block diagram illustrating a configuration of the cutout unit 112. The clipping unit 112 includes an image input unit 201, a frame memory 202, a region selection unit 203, an output unit 204, a region selection parameter input unit 205, and a region selection parameter storage unit 206. The cutout unit 122 is configured similarly.

  The image input unit 201 reads an image for one channel supplied from the image supply unit 101 and writes it into the frame memory 202 as digital image data. When the image is supplied as an analog signal, the A / D converter It is configured with.

  The frame memory 202 includes only two frames of a memory that can store an input image for one channel. The frame memory 202 is used for writing from the image input unit 201 for one frame, and the remaining one frame is used as an area. For reading from the selection unit 203, the odd frames and the even frames are used by alternately changing their roles.

  The area selection unit 203 cuts out a rectangular area that forms part of the image data on the frame memory 202 based on the area selection parameter stored in the area selection parameter storage unit 206, and performs appropriate resolution conversion. Output to the output unit 204. Here, the area selection parameter is a parameter for specifying a rectangular area on the frame memory 202. For example, the upper left coordinate value (X0, Y0) of the rectangular area in the coordinate system on the frame memory 202 and the rectangular area And a set of widths and heights (W, H). In addition to the configuration of parameters, there are a method of specifying the coordinate values of the upper left and lower right, a method of specifying the minimum and maximum values of the X and Y coordinates, and the specification of the coordinate values. Although various methods such as a method of performing the ratio with respect to the width and height of the entire image are conceivable, the parameters may be configured by any method as long as the rectangular region can be specified.

  Note that the resolution of the image to be output by the cutout unit 112, that is, the resolution after resolution conversion by the region selection unit 203, depends on the input resolution of the correction unit 113 (included in the display design parameter 432 described later). It is determined. The design value of the resolution is stored in advance in a storage unit (not shown) of the cutout unit 112 so that it can be referred to from the region selection unit 203.

  The output unit 204 converts the image output from the region selection unit 203 into an appropriate video signal and outputs the video signal to the correction unit 113, and the correction unit 113 is configured to input an analog video signal. If it is, it is configured with a D / A converter.

  The area selection parameter storage unit 206 stores area selection parameters input via the area selection parameter input unit 205. As the area selection parameter input unit 205, an apparatus that can receive an area selection parameter corresponding to an area selection parameter output unit 413 of the parameter generation unit 401 described later is used. For example, as the area selection parameter input unit 205, various devices such as a device for reading parameters from a storage medium such as a flash memory, a network interface, an RS-232C interface, a USB interface, and the like can be used. The user interface may be configured so that the user can manually input the region selection parameter 413 generated by the parameter generation unit 401.

  As a specific form of the cutout unit 112, a RAM can be used as the frame memory 202, a rewritable nonvolatile memory can be used as the region selection parameter storage unit 206, and an FPGA or an ASIC can be used as the region selection unit 203. However, embodiments of the present invention are not limited to these.

  FIG. 3 is a block diagram showing the configuration of the correction unit 113. The correction unit 113 includes an image input unit 301, a frame memory 302, a geometric correction unit 303, a pixel value conversion unit 304, an output unit 305, a geometric correction parameter input unit 306, a geometric correction parameter storage unit 307, and a pixel value conversion parameter input unit 308. The pixel value conversion parameter storage unit 309 is configured. The correction unit 123 is configured similarly.

  The image input unit 301 reads an image for one channel supplied from the cutout unit 112 and writes it into the frame memory 302 as digital image data. When the image is supplied as an analog signal, an A / D converter is used. It is prepared for.

  The frame memory 302 includes two frames of a size that can store an input image for one channel. The frame memory 302 is used for writing from the image input unit 301 for one frame, and the remaining one frame is geometric. For reading from the correction unit 303, the odd frames and the even frames are used while alternately switching their roles.

  Based on the geometric correction parameters stored in the geometric correction parameter storage unit 307, the geometric correction unit 303 sends image data obtained as a result of performing geometric correction to the image data on the frame memory 302 to the pixel value conversion unit 304. Output. The above-described geometric correction parameter is a parameter that defines how the pixel value of each pixel of the image data output from the geometric correction unit 303 is determined with reference to which pixel on the frame memory 302. It is. For example, for each pixel, a set of a real value X and a real value Y is stored, and is associated with a coordinate value (X, Y) on the frame memory 302, so that a reference color (for example, R, G, For each B), the pixel value may be determined by bilinear interpolation of four neighboring pixels. Note that if there is no corresponding coordinate value on the frame memory 302, a predetermined exception value is stored, and the geometric correction unit 303 is always “black” for such a pixel, that is, (R, G, B) = (0, 0, 0) is output.

  The pixel value conversion unit 304 converts the pixel value for each pixel in the image input from the geometric correction unit 303 based on the pixel value conversion parameter stored in the pixel value conversion parameter storage unit 309 and outputs the converted pixel value. This is output to the unit 305 and is a part that performs processing corresponding to correction of the color and brightness of the image. The resolution of the image to be input to the pixel value conversion unit 304 and the resolution of the image to be output from the pixel value conversion unit 304 are both made equal to the resolution of the image output from the correction unit 113. ing. The above-described pixel value conversion parameters are held as a look-up table in which output pixel values are determined for input pixel values independently of R, G, and B of each pixel, for example.

  The output unit 305 converts the image output from the pixel value conversion unit 304 into an appropriate video signal and outputs the video signal to the projection unit 114. The projection unit 114 is configured to project an analog video signal. In this case, a D / A converter is provided.

  The geometric correction parameter storage unit 307 stores the geometric correction parameters input via the geometric correction parameter input unit 306. As the geometric correction parameter input unit 306, a unit that can receive a geometric correction parameter corresponding to a geometric correction parameter output unit 414 of the parameter generation unit 401 described later is used. For example, as the geometric correction parameter input unit 306, various devices such as a device that reads parameters from a storage medium such as a flash memory, a network interface, an RS-232C interface, and a USB interface can be used.

  The pixel value conversion parameter storage unit 309 stores the pixel value conversion parameters input via the pixel value conversion parameter input unit 308. As the pixel value conversion parameter input unit 308, various devices can be used in accordance with the interface of the device that supplies the pixel value conversion parameters, similarly to the geometric correction parameter input unit 306. The pixel value conversion parameter stored in the pixel value conversion parameter storage unit 309 is generated in advance using an existing technique, and the one generated in advance is stored in the pixel value conversion parameter storage unit 309. As the pixel value conversion parameter, an image generated based on a display design parameter 432 described later is supplied from the image supply unit 101, and an original geometric correction parameter 433 described later is stored in the geometric correction parameter storage unit 307 to store the geometric value. This is a parameter that allows a desired image to be obtained on the screen 105 when the correction unit 303 performs geometric correction, and after the pixel value conversion unit 304 converts the display.

  As a specific form of the correction unit 113, a RAM as the frame memory 302, a rewritable nonvolatile memory as the geometric correction parameter storage unit 307 and the pixel value conversion parameter storage unit 309, a geometric correction unit 303 and a pixel An FPGA or an ASIC may be used as the value conversion unit 304, but embodiments of the present invention are not limited to these.

  FIG. 4 is a block diagram illustrating a configuration of a parameter generation unit 401 that generates parameters used by the cutout unit and the correction unit. In the following description, the parameter generation unit 401 is described as generating parameters for one display series, but is commonly used as generating parameters for a plurality of display series. The parameter generation unit 401 generates a region selection parameter used by the clipping unit 112 and a geometric correction parameter used by the correction unit 113, and selects a region for a series of videos supplied from the image supply unit 101. One parameter and one geometric correction parameter are generated and used when storing them in the storage unit of the cutout unit 112 and the correction unit 113. Therefore, the parameter generation unit 401 is not used when projecting an image using the video display system according to the embodiment of the present invention shown in FIG. 1, and may be separated from the video display system.

  The parameter generation unit 401 includes an arithmetic processing unit 411, a storage unit 412, a region selection parameter output unit 413, a geometric correction parameter output unit 414, and a command input unit 415.

  The arithmetic processing unit 411 uses the program and parameters stored in the storage unit 412 to perform processing on the command input from the command input unit 415 while using the storage unit 412 as appropriate. is there.

  The storage unit 412 includes a parameter generation program 421, an imaging parameter 431, a display design parameter 432, an original geometric correction parameter 433, an area selection parameter 434, a geometric correction parameter 435, and processing executed by the arithmetic processing unit 411. Intermediate data temporarily generated in the middle is stored, and for example, a set of a RAM and a hard disk, or a nonvolatile memory.

  The area selection parameter output unit 413 is configured to exchange area selection parameters in correspondence with the area selection parameter input unit 205 of the cutout unit 112, and writes parameters to a storage medium such as a flash memory, for example. Various devices such as a device, a network interface, an RS-232C interface, and a USB interface can be used.

  The geometric correction parameter output unit 414 is configured to exchange geometric correction parameters in correspondence with the geometric correction parameter input unit 306 of the correction unit 113, and writes parameters to a storage medium such as a flash memory, for example. Various devices such as a device, a network interface, an RS-232C interface, and a USB interface can be used.

  The command input unit 415 is used to input a command for starting the parameter generation program 421, an output command for an area selection parameter, and an output command for a geometric correction parameter, for example, a keyboard.

  The parameter generation program 421 is a program that generates an area selection parameter 434 and a geometric correction parameter 435 by inputting the imaging parameter 431, the display design parameter 432, and the original geometric correction parameter 433. The specific processing contents of the parameter generation program 421 will be described later with reference to FIG.

  The imaging parameter 431 is a parameter for calculating the three-dimensional direction from the photographing viewpoint position for each pixel position of the original image. In the embodiment of the present invention, since the image captured using the equidistant fisheye lens is supplied from the image supply unit 101, the imaging parameter 431 includes the coordinate position of the projection center in the coordinate system of the original image and the image circle. The radius, the angle of view of the fisheye lens, the width and height of the original image, and the imaging posture in the world coordinate system (= the three-dimensional coordinate system that the display design parameter 432 follows) are configured.

  In the embodiment of the present invention, processing is performed by ignoring high-order distortion of the fisheye lens. However, if the distortion cannot be ignored, the imaging parameter 431 may be configured to include parameters for expressing them. Further, the coordinate position of the projection center and the radius of the image circle described above may be estimated from the captured image. Specifically, using the fact that the area outside the image circle is generally photographed in a black or near-black state, the boundary line of the image circle is extracted by binarization processing, and a method such as Hough transform is used. The circle equation can be estimated.

  The display design parameter 432 includes the input resolution of each correction unit and “data corresponding to which three-dimensional direction each pixel of the image supplied to each correction unit is based on the virtual projection center position in the world coordinate system. And a parameter indicating whether or not.

  The original geometric correction parameter 433 is generated using an existing technique in advance, and an image generated based on the display design parameter 432 is supplied from the image supply unit 101 and is stored in the geometric correction parameter storage unit 307. This is a parameter generated so that a desired image can be obtained geometrically on the screen 105 when the correction parameter 433 is stored and displayed after geometric correction.

  The area selection parameter 434 is a parameter generated by the arithmetic processing unit 411 using the parameter generation program 421. For each display series, the upper left X coordinate value and Y of the rectangular area in the coordinate system on the original image are displayed. It is a parameter provided with coordinate values and the width and height of a rectangular area.

  The geometric correction parameter 435 is a parameter generated by the arithmetic processing unit 411 using the parameter generation program 421, and is used for resampling in the coordinate system on the frame memory for each pixel of the image supplied to the projection unit 114. It is a parameter having an X coordinate value and a Y coordinate value.

  Note that, in the coordinate system on the original image and the coordinate system on the frame memory, the position of the upper left corner is the origin (0, 0), and the X coordinate increases as it goes to the right, and the position goes down as it goes down. The coordinate system is configured so that the coordinates are large.

  FIG. 5 is a flowchart for explaining the parameter generation processing operation in the parameter generation unit, and FIG. 6 is a diagram for explaining the necessary range calculation method and the rectangular area extraction method. 5 and 6, only the processing for one display sequence will be described, but in practice, each processing is performed for each necessary display sequence. Further, steps 501 and 502 of the flow shown in FIG. 5 correspond to the process of calculating the necessary range 601 from the original image 600 and extracting the rectangular area 602 to be cut out based on the calculated necessary range 601 in FIG. . Hereinafter, the specific method will be described by taking as an example the case where the virtual projection center position and the photographing viewpoint position are matched.

(1) When parameter generation processing is started, first, necessary range calculation processing is executed. This necessary range calculation process is a process of marking a pixel to be referred to in order to determine a pixel value by a resampling process in the correction unit 113 on the original image. Specifically, for example, when the geometric correction unit 303 of the correction unit 113 is configured to determine pixel values by bilinear interpolation of four neighboring pixels, a binary image having the same size as the original image is prepared. The pixel value of the pixel is initialized with “0”, the coordinate value (x, y) of the reference source is calculated for each pixel for which the pixel value needs to be generated, and (x, y) is the original image X0 is “the maximum integer value not exceeding x”, x1 is “x0 + 1”, y0 is “the maximum integer value not exceeding y”, and y1 When “y0 + 1” is defined, the pixel values of the four points (x0, y0), (x0, y1), (x1, y0), and (x1, y1) are set to “1” on the binary image described above. It is processing to do. Here, the calculation of the coordinate value of the reference source is performed using the existing technique from the imaging parameter 431 and the display design parameter 432 (step 501).

(2) Next, rectangular area extraction processing is executed. This rectangular area extraction process includes a minimum range that includes the necessary range calculated in step 501 in the coordinate system on the original image and that each side of the area is parallel to each corresponding side of the original image. This is processing for extracting a rectangular area. For such a rectangular area, the minimum and maximum values of the X coordinate and the minimum and maximum values of the Y coordinate where the pixel having the pixel value “1” exists are obtained from the binary image generated in step 501. Thus, it can be extracted (step 502).

(3) Next, an area selection parameter saving process is executed. This area selection parameter saving process is a process of storing the rectangular area extracted in the process of step 502 in the storage unit 412 as an area selection parameter 434 by appropriate format conversion. When the region selection parameter output unit 413 and the region selection parameter input unit 205 of the cutout unit 112 are connected, the process of storing the region selection parameter in the region selection parameter storage unit 206 is performed simultaneously. (Step 503).

(4) Next, geometric correction parameter composition processing is executed. This geometric correction parameter combining process is a process of combining the original geometric correction parameter 433 and the geometric correction parameter for matching the input image cut out by the cutout unit with the design value. Here, the latter geometric correction parameter is used to correct a geometric correction function g (•) for correcting a difference in projection method between the imaging parameter 431 and the display design parameter 432, and correction accompanying extraction of a rectangular area. The geometric correction function h (•) and the geometric correction function k (•) for correcting the resolution conversion are synthesized. That is, in the geometric correction parameter synthesis process here, when the geometric correction by the original geometric correction parameter 433 is expressed by a function f (·), it is expressed by a synthesis function k (h (g (f (x)))). The geometric correction parameter is generated. Each function is a function that receives a two-dimensional coordinate value and outputs a two-dimensional coordinate value (step 504).

  The processing in step 504 will be described more specifically. First, in the geometric correction using the original geometric correction parameter 433, the pixel value of the pixel at the pixel position x is based on the coordinate f (x) on the frame memory. It is determined. However, since what is actually input to the geometric correction unit is an image generated by a projection method different from the projection method assumed in the display design parameters, both are considered in consideration of the three-dimensional structure in the world coordinate system. It is necessary to correct the discrepancy. By referring to the display design parameter 432, it can be seen that the coordinate f (x) on the frame memory corresponds to the three-dimensional direction d based on the virtual projection center position in the world coordinate system. By referring to the parameter 431, the coordinates g (f (x)) on the original image corresponding to the same direction d can be calculated. This coordinate value becomes a coordinate value h (g (f (x))) by moving the coordinate origin by cutting out the rectangular area. Furthermore, independent scale conversion is performed in each of the X direction and the Y direction to obtain a coordinate value k (h (g (f (x)))), which is an image output from the clipping unit, that is, This is the coordinate value to be resampled on the image input to the frame memory of the correction unit. Note that each geometric correction function can be easily generated by using an existing technique. Regarding exception processing, when f (x) matches the above-described exception value, the coordinate value after synthesis may be set to the same exception value, and g (f (x)) protrudes from the original image. Even in the case where h (g (f (x))) protrudes from the range of the rectangular area, the coordinate value after synthesis may be set as an exceptional value.

(5) Next, geometric correction parameter storage processing is performed. This geometric correction parameter saving process is a process for storing the geometric correction parameter synthesized in step 504 in the storage unit 412 as the geometric correction parameter 435. If the geometric correction parameter output unit 414 and the geometric correction parameter input unit 306 of the correction unit 113 are connected, the process of storing the geometric correction parameters in the geometric correction parameter storage unit 307 is performed simultaneously. (Step 505).

  After completion of the geometric correction parameter storage process in step 505, the parameter generation process is terminated.

  According to the first embodiment of the present invention described above, the clipping unit extracts a minimum rectangular area necessary for the processing of the correction unit from the high-resolution input image, and then processes the correction unit. The correction unit combines the conventional geometric correction parameter and the geometric correction parameter for matching the input image cut out by the cut-out unit with the design value. By performing geometric correction using the geometric correction parameter 2, it is possible to display an image shot using a fish-eye lens or the like at a lower cost than the prior art while suppressing deterioration in image quality. A video display system can be provided.

  In the first embodiment of the present invention described above, the number of cutout portions is the same as the number of projection portions. However, the embodiment of the present invention is not limited to this. For example, a system configuration may be adopted in which the cutout unit has the same number of output units as the number of projection units, and a single cutout unit supplies video to a plurality of correction units.

  In the first embodiment of the present invention described above, the image supplied by the image supply unit 101 is an image captured using an equidistant fisheye lens. However, the embodiment of the present invention is not limited to this. The imaging parameter 431, the necessary range calculation process 501, and the geometric correction parameter composition process 504 are not limited to those described above, and any configuration may be used. For example, an image based on a perspective transformation different from that assumed as a display design parameter may be used, or a horizontal angle of view of 360 degrees called an “axisymmetric free-form surface lens” can be captured at a time. It may be an image taken using an optical system. Furthermore, the image may be an image generated by a computer graphics technique based on various projection methods.

  Further, in the above-described first embodiment of the present invention, the case where the virtual projection center position and the photographing viewpoint position coincide with each other has been described, but the embodiment of the present invention is not limited to this. . For example, when the display design parameter 432 includes information on the shape, posture, and arrangement of the screen 105 and the coordinate value on the original image is calculated in the processing in step 501 and step 504 of the parameter generation processing, the “screen 105 By adopting a configuration that is obtained via the “corresponding point above”, the present invention is also applicable when it is desired to set the virtual projection center position and the photographing viewpoint position at different positions on the world coordinate system.

  Next, a video display system according to the second embodiment of the present invention will be described. In the second embodiment of the present invention, the parameter generation processing in the first embodiment described so far is modified so that the relationship of region selection parameters between a plurality of display series is taken into consideration. The other configuration is the same as that of the first embodiment.

  FIG. 7 is a flowchart for explaining the parameter generation processing operation in the second embodiment of the present invention, and FIG. 8 is a flowchart for explaining the details of the size adjustment processing in step 701 in the flow shown in FIG. In the flow shown in FIG. 7, steps 501 to 505 are the same processing as in FIG.

  As shown in FIG. 7, the parameter generation processing operation in the second embodiment of the present invention starts the area selection parameter storage process in step 503 after the rectangular area extraction process in step 502 described with reference to FIG. The difference from the first embodiment is that the process of step 701 for performing the size adjustment process is added before. Hereinafter, the size adjustment processing in step 701 will be described with reference to the flow shown in FIG.

(1) When the size adjustment process is started, first, a size determination process is executed. This size determination process is performed so that no defects occur in all display series, and the rectangular regions finally extracted from the original image for all display series have the same size. This is a process for determining the size of the rectangular area to be finally extracted from. Specifically, for all display sequences, the rectangular area extracted in step 502 is referred to, and the maximum width of the rectangular area is determined as the width of the rectangular area that is finally extracted from the original image. Similarly, the maximum value of the height of the rectangular area is determined as the height of the rectangular area finally extracted from the original image (step 801).

(2) Subsequently, position adjustment processing is executed. This position adjustment process is a process for solving the problem that the extracted rectangular area includes an area outside the original image as the size of the rectangular area is changed. Specifically, this is a process of correcting the upper left position of the rectangular area so that each display series includes the rectangular area extracted in step 502 and does not include the area outside the original image. . For example, when the X coordinate of the upper left position of the rectangular area is x0, the width of the rectangular area is w0, and the width of the original image is W (that is, the X coordinate value of the original image is 0 to W-1), “W If ≦ x0 + w0 ”, the rectangular area includes an area outside the original image. In this case, the value of“ W−w0-1 ”is changed to the X coordinate of the upper left position of the rectangular area. Eliminate. The same processing is performed for the Y coordinate, that is, the height direction (step 802).

  After the position adjustment process in step 802 is completed, the size adjustment process is terminated.

  According to the second embodiment of the present invention described above, since the pixel density on the original image used for calculating the pixel value can be matched between the overlapping projection areas, a plurality of images on the screen can be displayed. The joints between them can be made inconspicuous.

  Next, a video display system according to a third embodiment of the present invention will be described. In the third embodiment of the present invention, the size adjustment processing in the second embodiment described above is modified so that the number of interpolation calculations required for pixel value calculation as a whole is minimized.

  FIG. 9 is a flowchart for explaining the details of the size adjustment processing in the third embodiment of the present invention. The size adjustment process in the third embodiment of the present invention is obtained by changing the size determination process in step 801 in the size adjustment process in the second embodiment described with reference to FIG. In the following description, the resolution for one screen in the frame memory 302 of the correction unit 113 is defined as “reference size”.

  In the size selection process in step 901 in the size adjustment process according to the third embodiment of the present invention, either the reference size or the size of the rectangular area extracted in the process of step 502 is finally determined from the original image for each display series. This is a process for selecting whether the size of the rectangular area to be extracted is selected.

  Specifically, the size selection process compares the size of the rectangular area extracted in step 502 with the reference size for each display series in terms of width and height. Is selected as the size of the rectangular area finally extracted from the original image, otherwise, the rectangular area extracted in step 502 as the size of the rectangular area finally extracted from the original image This is a process of selecting the size of.

  According to the above-described third embodiment of the present invention, when the size of the rectangular region finally extracted from the original image is equal to the reference size, the interpolation operation for calculating the pixel value does not occur in the processing in the clipping unit. Therefore, the number of interpolation calculations required for pixel value calculation as a whole system can be reduced as much as possible in principle, and deterioration of video quality can be further suppressed.

  As can be seen from the first to third embodiments of the present invention described above, the essence of the present invention is to simplify and simplify the process for extracting a part necessary for displaying the assigned area from a high-resolution input image. The geometric correction processing required for this is combined with the geometric correction processing for smoothly connecting the images projected from multiple projectors on the screen, and is performed simultaneously. It goes without saying that the features described in each embodiment of the invention may be used in appropriate combination according to the application. For example, the mounting of the correction unit and the screen shape are not limited to those illustrated.

It is a block diagram which shows the structure of the video display system by the 1st Embodiment of this invention. It is a block diagram which shows the structure of a cutout part. It is a block diagram which shows the structure of a correction | amendment part. It is a block diagram which shows the structure of the parameter production | generation part which produces | generates the parameter which a cutout part and a correction | amendment part use. It is a flowchart explaining the processing operation | movement of the parameter generation in a parameter generation part. It is a figure explaining the required range calculation method and a rectangular area extraction method. It is a flowchart explaining the processing operation | movement of the parameter generation in the 2nd Embodiment of this invention. It is a flowchart explaining the detail of the size adjustment process in the flow shown in FIG. It is a flowchart explaining the detail of the size adjustment process in the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Image supply part 105 Screen 112, 122 Clipping part 113 123 Correction part 114 124 Projection part 201 Image input part 202, 302 Frame memory 203 Area selection part 204,305 Output part 205 Area selection parameter input part 206 Area selection parameter storage part 301 Image input unit 303 Geometric correction unit 304 Pixel value conversion unit 306 Geometric correction parameter input unit 307 Geometric correction parameter storage unit 308 Pixel value conversion parameter input unit 309 Pixel value conversion parameter storage unit 401 Parameter generation unit 411 Operation processing unit 412 Storage unit 413 Area selection parameter output unit 414 Geometric correction parameter output unit 415 Command input unit 421 Parameter generation program 431 Imaging parameter 432 Display design parameter 433 Original geometric correction parameter Meter 434 region selection parameters 435 geometric correction parameters

Claims (6)

An image supply unit that supplies an input image that is an image generated under conditions based on imaging parameters;
Based on the extraction parameters, an image cutout unit that cuts out a rectangular region that forms part of the input image and outputs the cutout image;
A correction unit that performs geometric correction on the clipped image based on a geometric correction parameter and outputs the corrected image;
A display unit for displaying the image output by the correction unit,
The geometric correction parameter is a correction parameter that allows a desired image to be obtained on the display unit when an image generated based on a projection parameter based on a design value of the display unit is corrected and output. A correction parameter and a second correction parameter that is a correction parameter for correcting a difference between an image generated based on the imaging parameter and the extraction parameter and an image generated based on the projection parameter are synthesized. A video display system characterized by being a correction parameter.   The video display system according to claim 1, wherein the image cutout unit also changes a pixel density. The display unit includes a plurality of display devices,
The video display system according to claim 1, wherein the cutout unit generates the cutout image corresponding to each of the plurality of display devices by cutting out rectangular regions having the same size.   The video display system according to claim 1, wherein the cutout unit cuts out a rectangular region having the same size as the cutout image.   The video display system according to claim 1, wherein the image supply unit supplies an image generated under a condition based on a fisheye projection system. An image supply unit that supplies an input image that is an image generated under conditions based on imaging parameters;
Cut out a rectangular region which forms a portion of the input image based on the extracted parameter, and image cropping section for outputting a cut-out image,
A correction unit that performs geometric correction on the clipped image based on a geometric correction parameter and outputs the corrected image;
A display unit for displaying an image output by the correction unit;
With
The geometric correction parameter is a parameter for generating a desired image geometrically in the display unit, and is a parameter generation method for generating the extraction parameter of the video display system, characterized in that:
A first step of calculating a cutout essential region that is a region that can be referred to in the processing in the correction unit, based on the projection parameter given as the design value of the display unit and the imaging parameter;
As a rectangular area including the cutout essential region, and a second step of determining the rectangular region cut out from the input image,
A parameter generation method comprising:

Images