JP2014137431A - Image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display system which is capable of continuing to normally display an overlay image even in the case that information of a chroma key color is not correct.SOLUTION: The image display system includes: a base PC 1 which outputs a base image and draws an arbitrary area on the base image in a chroma key color; and an overlay device 2 which receives the base image and an overlay image and can select display of the result of chroma key composition of an image obtained by changing the position and size of the overlay image, in an arbitrary area on the base image or display of the image in the front of the base image. The base PC 1 periodically transmits a command to the overlay device 2, and the overlay device 2 displays the image obtained by changing the position and size of the overlay image, in the front of the base image if failing to receive the command.

Description

  The present invention relates to an image display system that synthesizes an overlay image different from a base image in a specific color area drawn on a base image output by a personal computer (PC) or the like.

  An image area of a specific color is drawn on the base image, and image processing such as partial cutout, enlargement, reduction, etc. is performed on the overlay image in accordance with the size and position of the image area, and chromakey (chromakey) ) Is used to overlay the image area (hereinafter referred to as “chroma key overlay method”).

  In this case, the color of the image area is set to a chroma key color for overlay, the overlay image is displayed for pixels that match the chroma key color on the base image, and the base image is displayed as it is for pixels that do not match the chroma key color. (For example, refer to Patent Document 1).

  On the other hand, when displaying a plurality of overlay images on a base image, there is also an image display system that performs an overlay display by performing “image display priority processing” (hereinafter referred to as “forced overlay method”) (for example, , See Patent Document 2).

  As an image display system combining the two overlay methods, a conventional image display system that displays a plurality of images in an arbitrary size at an arbitrary position on the base image using a PC output as a base image will be described. Hereinafter, the base image PC is referred to as a “base PC”.

  In this image display system, a composite overlay image is generated by combining a plurality of overlay images by a forced overlay method, and then, when the composite overlay image and a base image are combined, they are combined by a chroma key overlay method (hereinafter, referred to as “composite overlay image”). , Referred to as “normal overlay mode”).

  By performing application software (hereinafter referred to as “control software”) on the base PC in order to perform composition by the chroma key overlay method, the base PC displays an area (overlay area) on which the overlay image on the base image is to be displayed. ) In chroma key color.

  Since the chroma key color is selected so as not to match the color of the mouse cursor, even if the mouse cursor of the base PC overlaps with the composite overlay image, the display of the mouse cursor does not disappear.

  In addition, since a portion where a plurality of overlay images overlap is synthesized by the forced overlay method, a plurality of overlay images can be displayed in a desired priority order by “image display priority order processing”.

  Furthermore, if the base image becomes no signal, the base image becomes no signal by switching to the operation mode that displays only the composite overlay image (hereinafter referred to as “forced overlay mode”). Even in this case, the display of the overlay image can be continued.

Japanese Patent Laid-Open No. 5-207368 JP 2004-355391 A

  However, the conventional image display system operates the control software on the base PC, so that the base PC fills the overlay area in chroma key color. If the control software malfunctions and stops, There is a problem that the overlay area and the chroma key color portion of the base image do not match and the overlay image is not displayed normally.

  In addition, since the conventional image display system does not switch to the forced overlay mode unless the base image becomes no signal, for example, a video signal output circuit of the base PC, a video switcher or a distributor disposed in the video signal transmission path, etc. If the color of the chroma key part cannot be transmitted correctly without causing the base image to become non-signaled due to failure of the device, partial disconnection of the video signal cable, poor contact, etc., the overlay image will not be displayed properly. there were.

  In the image display system for the purpose of overlay, it is fatal that the overlay image cannot be displayed normally. In this respect, the conventional image display system has a large operational risk.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image display system capable of normally displaying an overlay image even when the overlay area or chroma key color information transmitted by the video signal of the base image is not correct. To do.

  An image display system according to the present invention is an image display system that displays a second image superimposed on an arbitrary area on the first image, and outputs the first image and the first image. A base image output device that draws the arbitrary area on the image in chroma key color, and an image in which the first and second images are input and the position / size of the second image is changed is the first image An overlay device capable of selecting whether to display in the arbitrary region on the image with the chroma key composition or the front side of the first image, and the base image output device periodically transmits to the overlay device. When the overlay apparatus fails to receive the command, the overlay image is displayed on the front side of the first image.

  According to the present invention, the base image output device periodically transmits a command to the overlay device, and when the overlay device fails to receive the command, the position / size of the second image (overlay image) is changed. Since the image is displayed on the front side of the first image (base image), when the operation of the control software for drawing the chroma key color that operates on the base image output device stops, that is, the transmitted overlay area or chroma key color Even when the information is not correct, the second image (overlay image) can be normally displayed.

1 is a schematic block diagram of an image display system according to Embodiment 1. FIG. It is a figure explaining the image composition of an image display system. It is a flowchart which shows the pixel monitoring process by base PC. It is a flowchart which shows the abnormality detection process by an overlay apparatus. 10 is a flowchart showing an abnormality detection process by the overlay device of the image display system according to the second embodiment. 10 is a flowchart illustrating image monitoring processing by a base PC of the image display system according to the third embodiment.

<Embodiment 1>
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of an image display system according to Embodiment 1 of the present invention. The example in FIG. 1 is a multi-screen image display system, in which two display devices are arranged horizontally and vertically to form a large four-screen, and a large base image (first image) and two overlays are formed on the entire multi-screen. A composite image of the image (second image) is displayed.

  As shown in FIG. 1, the image display system includes a base PC 1, an overlay device 2, display devices 3 to 6, and overlay image output devices 7 and 8. The base PC 1 divides the base image into two in the horizontal direction and the vertical direction, and outputs the base image as four partial images. Each of the four partial images of the base image is input to the overlay apparatus 2. The overlay image output device 7 outputs a first overlay image, and the overlay image output device 8 outputs a second overlay image.

  The overlay apparatus 2 processes a video signal for the entire region of the base image of the base PC 1 by virtually reconstructing the base image of the base PC 1 from the four partial images of the base image input from the base PC 1. can do.

  By operating the control software on the base PC 1, the base PC 1 controls the display position, size, and priority order of the overlay image. More specifically, the base PC 1 fills an area (overlay area) in which an overlay image on the desktop image of the base PC 1 is to be displayed with a predetermined chroma key color, and also displays the overlay image display position, size, and priority on the overlay device 2. The order is notified by a control signal.

  For example, when an operating system having a mouse input function is operating on the base PC 1, a mouse cursor or the like is also displayed on the desktop image, and finally becomes a base image output from the base PC 1.

  The overlay apparatus 2 enlarges or reduces each of the two overlay images in accordance with the information notified from the base PC 1 and then combines them in the forced overlay method according to the designated priority and the designated positional relationship. Then, the overlay apparatus 2 synthesizes it at the designated position of the base image by the chroma key overlay method.

  As a result, the two overlay images input to the overlay apparatus 2 are synthesized at an arbitrary position on the base image output from the base PC 1 with an arbitrary size and an arbitrary display priority. FIG. 2 is a diagram for explaining image composition of the image display system. For example, as shown in FIG. 2, the first and second overlay images output by the overlay image output devices 7 and 8 are superimposed on the overlay area (hatched portion of the base image) on the base image output by the base PC 1. To display.

  The overlay device 2 divides and outputs four display images obtained by synthesizing the overlay image to each of the four partial images of the base image input from the base PC 1 into portions corresponding to the display devices 3 to 6 respectively. As a result, the base image of the base PC 1 in which two overlay images are combined is displayed on the entire multi-screen.

  By operating the control software on the base PC 1, the base PC 1 transmits a self-check command to the overlay apparatus 2 at regular time intervals t 0. The overlay apparatus 2 determines that the base PC 1 is in an abnormal state when the self-check command cannot be received every certain time interval t0, and controls to change to the forced overlay mode. In this case, since the overlay apparatus 2 can reliably detect the abnormality of the base PC 1, the overlay image can be displayed even when the operation of the control software for drawing the chroma key color is stopped in the base PC 1.

  By operating the firmware on the overlay apparatus 2, the overlay apparatus 2 determines that the base PC 1 has entered an abnormal state when it cannot receive a self-check command at regular time intervals t0, and enters the forced overlay mode. Control to change. In this case, since the overlay apparatus 2 can reliably detect the abnormality of the base PC 1, the overlay image can be displayed even when the control software for drawing the chroma key color is stopped.

  Furthermore, the image display system according to the present embodiment monitors an abnormality of the image display system by a pixel monitoring process and an abnormality detection process described below. The pixel monitoring process and the abnormality detection process will be described using a flowchart. In the following description of the pixel monitoring process, it is assumed that the base PC 1 outputs the entire base image as one system video signal. FIG. 3 is a flowchart showing pixel monitoring processing by the base PC 1, and FIG. 4 is a flowchart showing abnormality detection processing by the overlay apparatus 2.

  First, pixel monitoring processing by the base PC 1 shown in FIG. 3 will be described. When the control software is activated, a predetermined initialization process is executed. After the initialization process, the process of FIG. 3 is executed once for each display frame. For the sake of explanation, assuming that the vertical synchronization frequency of the video signal is 60 Hz, the processing of FIG. 3 is executed every 1/60 seconds.

  The pixel monitoring process by the base PC 1 shown in FIG. 3 will be described in detail. The base PC 1 acquires the color Cref value of the reference pixel on the base image (step S1). The position of the reference pixel is assumed to be one pixel at the upper left corner of the base image. Next, the base PC 1 compares the acquired Cref value with the Cpre value (step S2).

  As the Cpre value, the Cref value 1/60 second before is stored in advance in the initialization process, and when the pixel monitoring process shown in FIG. 3 is executed for the first time, the Cpre value stored in the initialization process is used. . In the second and subsequent pixel monitoring processes, the Cref value acquired in the previous process is stored as the Cpre value (step S7), and this Cpre value is used. If the Cref value and the Cpre value do not match (No in step S2), the base PC 1 clears the match counter N to 0 (step S6), and substitutes the Cref value into Cpre (step S7). The monitoring process ends.

  If the Cref value and the Cpre value match (Yes in step S2), the base PC 1 adds 1 to the match counter N (step S3). Here, the coincidence counter N is cleared to 0 in the initialization process.

  The base PC 1 continues to determine whether or not the coincidence counter N exceeds a predetermined value, so that the Cref value has not changed for a first time (hereinafter referred to as “color change non-determination determination time t1”). Determine if. For the sake of explanation, it is assumed that the color change absence determination time t1 is 5 seconds. Since this processing is executed every 1/60 seconds according to the above description, the base PC 1 determines whether or not the coincidence counter N exceeds 300 corresponding to 5 seconds, so that the Cref value changes for 5 seconds. It is determined whether it is not (step S4).

  If the determination time t1 of no color change does not exceed 5 seconds, that is, if the coincidence counter N does not exceed 300 (No in step S4), the base PC1 substitutes the Cref value for Cpre (step S7). The pixel monitoring process ends.

  If the determination time t1 of no color change exceeds 5 seconds, that is, if the coincidence counter N exceeds 300 (Yes in step S4), the base PC 1 notifies the overlay device 2 of the Cref value (step S5). Thereafter, the coincidence counter N is cleared to 0 (step S6), the Cref value is substituted for Cpre (step S7), and the pixel monitoring process is terminated.

  By operating the control software on the base PC 1 as described above, when the color of the reference pixel does not change during the non-color change determination time t1, the base PC 1 sets the color Cref value of the reference pixel to the overlay device 2. Notify

  Next, the abnormality detection process by the overlay apparatus 2 will be described. When the firmware of the overlay apparatus 2 is activated, a predetermined initialization process is executed. After the initialization process, the abnormality detection process shown in FIG. 4 is executed once every predetermined time shorter than ½ of the no-color change determination time t1. For the sake of explanation, it is assumed that the abnormality detection process shown in FIG. 4 is executed every 2 seconds.

  In parallel with the abnormality detection process shown in FIG. 4, when the reference pixel color Cref value is notified from the base PC 1, the overlay apparatus 2 updates the Cref value and simultaneously sets the notification flag F to 1. Here, the notification flag F is cleared to 0 at the time of activation.

  The abnormality detection process shown in FIG. 4 will be described in detail. First, the overlay apparatus 2 acquires the color Ctrg value of the reference pixel on the base image virtually reconstructed inside the overlay apparatus 2 (step S11). Here, Ctrg is the color of the reference pixel at the same position as the Cref value notified from the base PC 1. In accordance with the description of the pixel monitoring process shown in FIG. 3, the position of the reference pixel is assumed to be the pixel at the upper left corner of the base image.

  Next, the overlay apparatus 2 checks the notification flag F (step S12). When the notification flag F is not 1 (No in step S12), the overlay apparatus 2 substitutes the Ctrg1 value for Ctrg2 (step S16), and then substitutes the Ctrg value for Ctrg1 (step S17), and ends the abnormality detection process. To do.

  If the notification flag F is 1 (Yes in step S12), the overlay apparatus 2 compares the Cref value notified from the base PC 1 with the Ctrg2 value (step S13), and the Cref value and the Ctrg2 value match. If not (No in step S13), the overlay apparatus 2 sets the forced overlay mode (step S14).

  As the Ctrg2 value, the Ctrg value of 4 seconds before is stored in advance in the initialization process, and when the abnormality detection process shown in FIG. 4 is executed for the first time, the Ctrg2 value stored in the initialization process is used. In addition, the Ctrg1 value is stored in advance with the Ctrg value two seconds before in the initialization process, and is substituted into Ctrg2 in the first abnormality detection process shown in FIG. 4 (step S16), and the second time shown in FIG. Used as Ctrg2 value for abnormality detection processing. In the abnormality detection process shown in FIG. 4 after the third time, the Ctrg value acquired in the abnormality detection process shown in FIG. 4 two times before is stored as the Cpre2 value, and this Ctrg2 value is used.

  When the Cref value and the Ctrg2 value match (Yes in step S13) or after the forced overlay mode is set (step S14), the overlay apparatus 2 clears the notification flag F to 0 (step S15). Next, the overlay apparatus 2 substitutes the Ctrg1 value for Ctrg2 (step S16), and then substitutes the Ctrg value for Ctrg1 (step S17), and ends the abnormality detection process.

  Here, the relationship between the timing at which the Cref value notified from the base PC 1 is acquired and the timing at which the overlay apparatus 2 acquires the Ctrg2 value will be described.

  As is clear from the above description, the Cref value has not changed in the past 5 seconds from the time when the Cref value is notified from the base PC 1 to the overlay apparatus 2. On the other hand, the Ctrg2 value to be compared with the Cref value is a Ctrg value about 2 to 4 seconds before the time when the Cref value is notified. That is, when the timing at which the Cref value is notified is immediately before executing the abnormality detection process shown in FIG. 4, the Ctrg2 value is the Ctrg value acquired in the abnormality detection process shown in FIG. It has been acquired.

  Further, when the timing at which the Cref value is notified is immediately after the abnormality detection process shown in FIG. 4 is executed, the abnormality detection process shown in FIG. 4 is executed after about 2 seconds, and the Ctrg2 value is Since it is a Ctrg value acquired two times before, which is a value acquired about 4 seconds before that point, if the Cref value is notified, the Ctrg value is about 2 seconds before. That is, the Cref value that has not changed for 5 seconds is compared with the Ctrg value of about 2 to 4 seconds before.

  As described above, in the image display system according to the first embodiment, the base PC 1 periodically transmits a command to the overlay apparatus 2, and the overlay apparatus 2 cannot receive the command. Since the resized image is displayed on the front side of the base image, even if the operation of the control software operating on the base PC 1 is stopped, that is, even if the transmitted overlay area or chroma key color information is not correct, the overlay is displayed. Images can be displayed normally.

  In addition, the base PC 1 notifies the overlay device 2 of a predetermined pixel color in the base image, and the overlay device 2 determines the color notified from the base PC 1 and the predetermined base image in the base image reconstructed by itself. When the colors do not match when compared with the color of the pixel, an image in which the position / size of the overlay image is changed is displayed on the front side of the base image.

  That is, the color of the reference pixel of the base image notified from the base PC 1 is compared with the color of the reference pixel acquired from the image transmitted as the video signal of the base image to the overlay apparatus 2, and if they do not match, the forced Since the overlay mode is selected, the overlay image can be displayed even if the color of the chroma key part cannot be transmitted correctly without the base image becoming no signal due to equipment failure, signal cable disconnection, or poor contact. .

  The base PC 1 monitors a predetermined pixel color in the base image for each display frame, and if the predetermined pixel color does not change during the first time, the base PC 1 stores the color in the overlay device 2 in advance. The overlay device 2 notifies the color of the predetermined pixel, and the overlay device 2 determines the color notified from the base PC 1 and the predetermined pixel in the base image reconstructed by the overlay apparatus 2 before the second time shorter than the first time. Compare with the color.

  More specifically, when the reference pixel on the base PC 1 does not change during the non-color change determination time t1, the base PC 1 notifies the overlay device 2 of the color Cref value of the reference image, and the overlay device 2 side. In this case, the reference pixel is constantly monitored at intervals shorter than ½ of t1, and a notification flag F that is set when the Cref value is notified from the base PC 1 is used as a trigger to perform an abnormality detection process on the overlay device 2 the previous time. A transmission error is detected by comparing the obtained color Ctrg2 value of the reference pixel with the color Cref value of the reference pixel notified from the base PC1.

  That is, in order to compare the color values of the reference images of the base PC 1 and the overlay apparatus 2 using a period in which the color of the reference pixels does not change for a certain time or more, the timing of obtaining the color values of the reference pixels is strictly synchronized. Abnormality can be detected without making it happen.

  Therefore, a complicated mechanism for completely synchronizing the frame corresponding to the reference pixel that notifies the color from the base PC 1 and the frame corresponding to the reference pixel to be compared on the overlay apparatus 2 is unnecessary, and the system can be simplified. .

  Note that the variables Cref, Cpre, Ctrg, Ctrg1, and Ctrg2 used in the description are all values representing a specific color among colors that can be displayed by the image display system. For example, each of R, G, and B has 8 bits. Consists of 24-bit information.

  In the description of the pixel monitoring process by the base PC 1, since the base PC 1 outputs the entire base image as one system of video signals, the position of the reference pixel is assumed to be one pixel at the upper left corner of the base image. However, in the case of the multi-screen image display system shown in FIG. 1, four partial images of the base image are transmitted by four video signals, so that the reference pixels to be monitored are four reference images of the base image. One or more are set in the area of each partial image, and pixel monitoring processing is performed for each reference pixel.

  In addition, when an abnormality is detected in any of the video signals, when the entire multi-screen is set to the forced overlay mode, even in the portion of the base image transmitted with the remaining three video signals in which no abnormality is detected, If the window or mouse cursor on the base image that should be displayed in front by chroma key composition is hidden under the overlay image, it will not be visible. Depending on which of the four video signals is detected abnormal or normal Thus, the overlay apparatus 2 may be controlled so as to switch between the forced overlay mode and the normal overlay mode for every four display images.

  Each pixel monitoring process may be parallel processing or sequential processing by time division. In the case of parallel processing, the load of pixel monitoring processing increases as the number of multi-screens increases. However, if there is sufficient processing capability, there is an effect that an abnormality can be detected within a predetermined time. On the other hand, in the case of sequential processing, as the number of multi-screens increases, the time until abnormality detection becomes longer, but there is an effect that the load of pixel monitoring processing hardly increases.

  In addition, the multi-screen image display system has four screens and the number of overlay images is two. However, an overlay image with an arbitrary number of surfaces may be superimposed on an image display system with an arbitrary number of surfaces. .

  The base PC 1 always executes the image monitoring process shown in FIG. 3 at intervals of 1/60 seconds, and the overlay apparatus 2 always executes the abnormality detection process shown in FIG. 4 at intervals of 2 seconds. May be controlled to be executed for a predetermined period with a predetermined time interval while synchronizing. For example, a self-check command is transmitted from the base PC 1 side to the overlay apparatus 2 at intervals of, for example, 30 seconds, and the transmission or reception of this command is used as a trigger, and the base PC 1 performs the image monitoring process shown in FIG. The apparatus 2 controls to perform the abnormality detection process shown in FIG. 4 for 15 seconds, for example. In this case, the processing load of FIG. 3 and FIG. 4 is not executed for 15 seconds at 30-second intervals on each device, so that the execution load can be reduced.

  The base PC 1 sends a self-check command and a reference pixel color value to the overlay apparatus 2, and the overlay apparatus 2 detects an abnormality in the base PC 1 or base image. The reference device color Cref value and the reference pixel color Ctrg value from the overlay device 2 every t1 / 2 are received by the third device, and a communication error or device is detected in the same manner as in the above embodiment. It is also possible to detect an abnormality such as a failure of the cable or disconnection of the cable, and when the abnormality is detected, control may be performed so that the overlay device 2 is changed to the forced overlay mode from the third device.

<Embodiment 2>
Next, an image display system according to Embodiment 2 will be described. FIG. 5 is a flowchart showing pixel monitoring processing by the overlay apparatus 2 of the image display system according to the second embodiment. In the second embodiment, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  First, pixel monitoring processing when the control software is operated on the base PC 1 will be described. It is assumed that the control software is operating on an operating system having a mouse input function. When the control software is operated on the base PC 1, the base PC 1 acquires the Lref value indicating the coordinates of the mouse cursor displayed on the base image once for each display frame, and the acquired Lref value is obtained from the base PC 1. Notification by a control signal.

  In the second embodiment, since the base PC 1 operates as described above, it is not necessary to monitor the color of the pixel, and it is not necessary to perform heavy graphics processing. Alternatively, a special H / W function or a graphics driver for supporting the pixel color monitoring by the base PC 1 is not required. The coordinate information of the mouse cursor can be acquired from the operating system. Therefore, the control software is relatively light and can be easily created.

  When the firmware of the overlay apparatus 2 is activated, a predetermined initialization process is executed. The overlay apparatus 2 clears the coincidence counter N to 0, and initializes a variable Lpre value for storing the coordinates of the mouse cursor, for example, to a value indicating the upper left corner of the base image. After the initialization process, the abnormality detection process shown in FIG. 5 is executed once for each display frame. For the sake of explanation, assuming that the vertical synchronization frequency of the video signal is 60 Hz, the abnormality detection process shown in FIG. 5 is executed every 1/60 seconds. Both Lref and Lpre are values indicating a unique combination of the X coordinate and Y coordinate of the mouse cursor.

  The abnormality detection process shown in FIG. 5 will be described in detail. First, the overlay apparatus 2 compares the coordinate Lref value and the Lpre value of the mouse cursor notified from the base PC 1 (step S21). If the Lref value does not match the Lpre value (No in step S21), the overlay apparatus 2 clears the match counter N to 0 (step S29), substitutes the Lref value for Lpre (step S30), and abnormal The detection process ends.

  When the Lref value and the Lpre value match (Yes in Step S21), the overlay apparatus 2 adds 1 to the match counter N (Step S22). Next, the overlay apparatus 2 checks the value of N (step S23). If N matches the predetermined first count value (Yes in step S23), the overlay apparatus 2 virtually reconfigures inside the overlay apparatus 2. The color Ctrg value of the pixel at the coordinate Lref on the base image thus obtained is acquired (step S24). If N does not match the predetermined first count value (No in step S23), the overlay apparatus 2 proceeds to step S25.

  For the sake of explanation, assuming that the first count value is 60, the abnormality detection process is executed every 1/60 seconds according to the above description. As a result, if the Lref value does not change for 1 second, the Ctrg value is To be acquired. In other words, the Ctrg value after the first time t1 (here, temporarily 1 second) after the Lref value does not change is acquired. The overlay apparatus 2 continues to determine whether or not the coincidence counter N exceeds a predetermined second count value, whereby the Lref value is longer than the first time (hereinafter referred to as “no coordinate change”). It is determined whether it has changed (referred to as “determination time t2”) (step S25).

  For the sake of explanation, it is assumed that the coordinate change absence determination time t2 is 2 seconds. As described above, since the abnormality detection process is executed every 1/60 seconds, the second count value corresponding to 2 seconds is 120. Therefore, the overlay apparatus 2 can determine whether or not the Lref value has changed for 2 seconds by determining whether or not the coincidence counter N exceeds 120.

  If the Lref value does not exceed 2 seconds of the no coordinate change determination time t2, that is, if the coincidence counter N does not exceed 120 of the second count value (No in step S25), the overlay apparatus 2 sets Lpre to The Lref value is substituted (step S30), and the abnormality detection process is terminated.

  When the Lref value exceeds 2 seconds of the no coordinate change determination time t2, that is, when the coincidence counter N exceeds the second count value (Yes in step S25), the overlay apparatus 2 determines the Ctrg value and the predetermined Cref value. Are compared (step S26). Here, in the second embodiment, the Cref value is a pixel color indicated by the coordinates of the mouse cursor set in advance on the base PC 1 and is a predetermined fixed color.

  If the Ctrg value and the Cref value do not match (No in step S26), the overlay apparatus 2 sets the forced overlay mode (step S27). If the Ctrg value matches the Cref value (Yes in step S26), the overlay apparatus 2 sets the normal overlay mode (step S28).

  After setting the forced overlay mode or the normal overlay mode, the overlay apparatus 2 clears the match counter N to 0 (step S29), substitutes the Lref value for Lpre (step S30), and ends the abnormality detection process.

  Here, the relationship between the timing at which the Lref value notified from the base PC 1 is acquired and the timing at which the overlay apparatus 2 acquires the Ctrg value will be described.

  As is clear from the above description, the Ctrg value to be compared with the Cref value is obtained one second before the comparison time point. On the other hand, the Lref value has not changed in the past 2 seconds from the comparison time. Therefore, since the Ctrg value acquisition timing is in the middle of 2 seconds when the Lref value does not change, there is a margin of 1 second before and after.

  As described above, in the image display system according to the second embodiment, the base PC 1 notifies the overlay device 2 of the coordinates of the mouse cursor, and the overlay device 2 changes the coordinates of the mouse cursor at the first time. If it is determined that there is not, it is determined whether or not the color of the pixel at the coordinates of the mouse cursor in the base image is a predetermined fixed color.

  More specifically, the base PC 1 notifies the overlay apparatus 2 of the coordinate information Lref value of the mouse cursor for each display frame, and the overlay apparatus 2 monitors the change in the coordinates of the mouse cursor for each display frame. . When the coordinates of the mouse cursor do not change during the period t1, the overlay apparatus 2 acquires the pixel color Ctrg value with respect to the coordinate position of the mouse cursor. When the mouse cursor coordinate does not change for the period t2, the overlay apparatus 2 detects a transmission error by comparing the Ctrg value acquired before (t2-t1) time with the color Cref value of the pixel at the mouse cursor coordinate. To do.

  That is, using a period in which the position of the mouse cursor has not changed for a certain time or more, the color value of the pixel at the coordinate of the mouse cursor on the overlay apparatus 2 and the color value of the pixel at the coordinate of the mouse cursor set in advance are Therefore, the abnormality can be detected without strictly synchronizing the timing at which the coordinates of the mouse cursor are acquired in the base PC 1 and the timing at which the color values of the pixels at the coordinates of the mouse cursor are acquired in the overlay apparatus 2.

  Therefore, a complicated mechanism for completely synchronizing the frame corresponding to the coordinate information of the mouse cursor notified from the base PC 1 and the frame corresponding to the pixel of the coordinate of the mouse cursor to be compared on the overlay device is unnecessary. The system can be simplified.

  Further, since the base PC 1 does not need to monitor the pixel color and the coordinate information of the mouse cursor can be obtained from the operating system, the control software is relatively light in processing and can be easily created.

  The color information of the base image is composed of one or more color elements, and a fixed value different from the value of each color element in the case of no signal is selected as the value of each color element of the fixed color. If the fixed color matches the color of the pixel at the coordinates of the mouse cursor in the base image reconstructed before the second time shorter than the first time, the position and size of the overlay image match. The image with the changed color is combined with a chroma key and displayed in an arbitrary area on the base image.

  More specifically, the comparison between the Ctrg value and the Cref value in the second embodiment is that the color of the base image is not correctly transmitted due to equipment failure, signal cable disconnection or contact failure, that is, color abnormality. It is executed for the purpose of detecting. A general video signal is transmitted by separating a color into a plurality of color elements such as R, G, and B, for example. In this case, there is a high possibility that any value of each color element becomes the same value as when there is no signal due to some trouble in the transmission path. For this reason, the accuracy of abnormality detection is increased by setting the value of each color element of the fixed color to a value different from that at the time of no signal.

  In a general video signal, the value of each color element when there is no signal is 0 and indicates black. In this case, the fixed color is, for example, white in which all of R, G, and B are maximum values (hereinafter, all White), or R, G, and B are set to gray of an intermediate gradation.

  In the first embodiment, since the Cref value, which is a color used for determination of color abnormality detection, changes depending on the base image, any of the color components of the Cref value may include the same value as when there is no signal. There is sex. Therefore, depending on the display content of the base image, there is a possibility of overlooking color mismatch due to abnormality. Also, if any of the color components of the Cref value includes the same value as when there is no signal, if it is determined that the colors do not match, the result means that there is a transmission error, but the color is The determination result that they match does not necessarily mean that there is no transmission error. This problem can be avoided by using only non-zero colors for R, G, and B for the base image, but this is not desirable as a solution because it reduces the displayable colors.

  In this regard, in the second embodiment, the Cref value can be fixed to, for example, all white, so that a color mismatch is not overlooked. As a result, it is possible to automatically return to the normal overlay mode when the trouble such as the cable disconnection is resolved and the normal state is restored.

  In addition, when an abnormality is detected in any of the video signals, when the entire multi-screen is set to the forced overlay mode, even in the portion of the base image transmitted with the remaining three video signals in which no abnormality is detected, If the window or mouse cursor on the base image that should be displayed in front by chroma key composition is hidden under the overlay image, it will not be visible. Depending on which of the four video signals is detected abnormal or normal Thus, the overlay apparatus 2 may be controlled so as to switch between the forced overlay mode and the normal overlay mode for every four display images.

<Embodiment 3>
Next, a video display system according to Embodiment 3 will be described. FIG. 6 is a flowchart showing an image monitoring operation by the base PC of the image display system according to the third embodiment. In the third embodiment, the same components as those described in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  The third embodiment of the present invention is an embodiment in which the pixel monitoring process when the control software is executed on the base PC 1 is changed from the second embodiment. The base PC 1 cyclically moves the coordinates of the mouse cursor to be subject to pixel monitoring to each area of the partial images of the plurality of base images, and performs pixel monitoring processing on the pixels at the coordinates of each mouse cursor. Note that the abnormality detection process by the firmware of the overlay apparatus 2 of the image display system according to the present embodiment is the same as that of the second embodiment described with reference to FIG.

  When the control software of the base PC 1 is activated, a predetermined initialization process is executed. The base PC 1 clears the coincidence counter N to 0, initializes the M value indicating the system number (an integer of 1 to 4 in the example of FIG. 1) of the video signal to be monitored, and executes pixel monitoring. The MODE value indicating the mode (1) or the stop mode (0) is initialized to 0, and the variable Lpre value for storing the coordinates of the mouse cursor is initialized to, for example, a value indicating the upper left corner of the base image. . Here, the system numbers 1 to 4 of the video signals are numbers corresponding to the video signals respectively input to the display devices 3 to 6.

  After the initialization process, the pixel monitoring process shown in FIG. 6 is executed once for each display frame. For the sake of explanation, assuming that the vertical synchronization frequency of the video signal is 60 Hz, the pixel monitoring process shown in FIG. 6 is executed every 1/60 seconds.

  The pixel monitoring process shown in FIG. 6 will be described in detail. When the control software is executed on the base PC 1, the base PC 1 acquires the coordinate Lref value of the mouse cursor from the operating system (step S31). Next, the base PC 1 compares the acquired Lref value with the Lpre value (step S32).

  Here, as the Lpre value, for example, a value indicating the upper left corner of the base image is stored in the initialization process, and when the pixel monitoring process shown in FIG. 6 is executed for the first time, the Lpre value stored in the initialization process is stored. Is used. In the second and subsequent pixel monitoring processes shown in FIG. 6, the Lref value acquired in the previous pixel monitoring process is stored as the Lpre value (step S47), and this Lpre value is used.

  When the Lref value does not match the Lpre value (No in step S32), the base PC 1 sets the MODE value to 0 (step S33), and notifies the overlay device 2 of the Lref value (step S34). The coincidence counter N is cleared to 0 (step S46), the Lref value is substituted for Lpre (step S47), and the pixel monitoring process is terminated.

  When the Lref value and the Lpre value match (Yes in step S32), the base PC 1 adds 1 to the match counter N (step S35). Here, the coincidence counter N is initialized to 0 at the time of activation.

  Next, the base PC 1 checks whether or not the MODE value is 0 (step S36). If the MODE value is 0 (Yes in step S36), the base PC 1 determines whether or not the mouse cursor has not been moved for a third time (hereinafter, no coordinate change determination time t3) (step S37).

  For the sake of explanation, the coordinate change absence determination time t3 is assumed to be 5 seconds. Since the pixel monitoring process is executed every 1/60 seconds according to the above description, the base PC 1 determines whether or not the match counter N exceeds 300 corresponding to 5 seconds, so that the Lref value is 5 seconds. It is determined whether it has not changed, that is, whether the mouse cursor has not been moved for t3 time (step S37).

  When the coincidence counter N is 300 or less (No in step S37), the base PC 1 substitutes the Lref value for the Lpre value (step S47), and ends the pixel monitoring process. When the coincidence counter N exceeds 300 (Yes in Step S37), the base PC 1 changes the MODE value to 1 (Step S39). When the base PC 1 changes the MODE value to 1 in step S39, the base PC 1 continues to start the pixel monitoring operation.

  In the pixel monitoring operation in the third embodiment, a reference pixel corresponding to each area of the partial image constituting the base video is determined, and each reference is performed every fourth time (hereinafter referred to as “pixel monitoring time t4”). The pixels are cyclically moved to check the color of each reference pixel. In the example of the multi-screen pixel display system shown in FIG. 1, since there are four base image portions, a value indicating the position of the reference pixel on each surface is Lref (M). Here, M is a system number of the video signal to be subject to pixel monitoring, and is an integer from 1 to 4. Lref (M) is a value indicating a unique combination of the X coordinate and the Y coordinate of the mouse cursor, like Lref and Lpre.

  When the pixel monitoring operation is started, the base PC 1 moves the mouse cursor to Lref (M) (step S40), substitutes the Lref (M) value for the Lref value (step S41), and sets the Lref value to the overlay apparatus 2. Is notified (step S42).

  Thereafter, the base PC 1 checks whether or not the M value is the maximum value 4 (step S43). If M = 4 (Yes in step S43), the base PC 1 resets the M value to 1 (step S44). On the other hand, if M ≠ 4 (No in step S43), the base PC 1 adds 1 to the M value (step S45). The cyclic movement of the four reference pixels is controlled by such reset / increment operation of the M value. Thereafter, the base PC 1 clears the match counter N to 0 (step S46), substitutes the Lref value into Lpre (step S47), and ends the processing of this execution cycle.

  If the mouse cursor has not moved in the next execution cycle, the base PC 1 enters the process when the MODE value is not 0 in step S36 according to the flow described above. It is checked whether the time during which the mouse cursor has not moved exceeds the pixel monitoring time t4 after the M value has been changed in step S44 or step S45 of the execution cycle.

  For explanation, it is assumed that the pixel monitoring time t4 is 2.5 seconds. Since the present pixel monitoring process is executed every 1/60 seconds as described above, the base PC 1 determines whether or not the coincidence counter N exceeds 150 corresponding to 2.5 seconds (step S38).

  When the coincidence counter N is 150 or less (No in step S38), the base PC 1 substitutes the Lref value for the Lpre value (step S47), and ends the processing of this execution cycle. When the coincidence counter N exceeds 150 (Yes in step S38), the processing of step S40 to step S42 described above is performed, and the pixel monitoring operation of the reference pixel corresponding to the latest M value is executed. The processing after step S43 is also as described above.

  The coordinate change absence determination time t3 and the pixel monitoring time t4 are longer than the coordinate change absence determination time t2 described in the second embodiment. According to the flow of the third embodiment, in the pixel monitoring execution mode, the Lref value notified to the overlay apparatus 2 is not updated at least during the period t3 or t4. Therefore, if t3> t2 and t4> t2, it is determined that the predetermined time has been exceeded in step S25 described in FIG. 5, and the color value comparison operation, that is, the abnormality detection operation in step S26 is executed.

  As described above, in the image display system according to the third embodiment, the base PC 1 divides and outputs the base image into a plurality of areas, and the mouse cursor is moved every third time longer than the first time. Control to move around multiple areas.

  More specifically, the base PC 1 shifts to the pixel monitoring execution mode when the coordinates of the mouse cursor do not change for the period t3, and when the mouse cursor is operated to change the coordinates of the mouse cursor, the pixel monitoring execution mode is set. Exit. During the pixel monitoring execution mode, the base PC 1 cyclically moves the mouse cursor to predetermined coordinates in each area of the partial images of the plurality of base images every t3 period longer than the t2 period. Pixel monitoring, that is, abnormality detection is performed on the pixel at the coordinate. Thereby, an abnormality of the multi-screen image display system can be reliably detected with one mouse cursor.

  In the third embodiment, the coordinates of the mouse cursor are notified from the base PC 1 to the overlay apparatus 2. However, the value of the reference pixel Lref (M) of each surface is held in advance in the overlay apparatus 2, and the base PC 1 May notify the system number M value of the video signal to be monitored.

  The base PC 1 may change the design of the mouse cursor when it is determined that no mouse operation is performed on the mouse cursor. That is, during the pixel monitoring execution mode, the opaque color portion of the mouse cursor is, for example, only one pixel indicated by the coordinates of the mouse cursor, and the color is expected to have the smallest maximum contrast with the surrounding image. It is possible to switch to a normal mouse cursor image in gray shades and in the pixel monitoring stop mode.

  During the pixel monitoring execution mode, mouse operation is not performed, so the mouse cursor does not need to stand out. Rather, the mouse cursor displayed on the screen is displayed on the screen, for example, by setting it to a gray dot of one pixel. The pixel monitoring can be executed without disturbing the monitoring of information. When a mouse operation is performed, the normal mouse cursor is quickly returned, so that the mouse operation is not hindered.

  In addition, the opaque color portion of the mouse cursor is not limited to the gray of one intermediate tone, but is displayed depending on the relationship between the pixel size of the display devices 3 to 6 and the assumed viewing distance, the content to be actually displayed, The number of pixels, the shape, and the color need only be in a range that does not hinder the monitoring of information.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  1 Base PC, 2 Overlay device.

Claims (7)

An image display system that displays a second image superimposed on an arbitrary area on the first image,
A base image output device for outputting the first image and drawing the arbitrary region on the first image in a chroma key color;
The first and second images are input, and the image in which the position and size of the second image are changed is displayed on the arbitrary region on the first image by chroma key composition, or the first image is displayed. An overlay device capable of selecting whether to display on the front side of one image,
The base image output device periodically sends commands to the overlay device,
An image display system in which the overlay device displays an image in which the position / size of the second image is changed in front of the first image when the command cannot be received. The base image output device notifies the overlay device of a predetermined pixel color in the first image;
The overlay device compares the color notified from the base image output device with the color of a predetermined pixel in the first image reconstructed by the overlay device and does not match the second color. The image display system according to claim 1, wherein an image whose position and size are changed is displayed on the front side of the first image. The base image output device monitors the color of a predetermined pixel in the first image for each display frame, and when the color of the predetermined pixel does not change at a first time, Notifying the overlay device of the predetermined pixel color;
The overlay device includes a color notified from the base image output device, and a color of a predetermined pixel in the first image that is reconstructed by the device itself before a second time shorter than the first time. The image display system of Claim 2 which compares. The base image output device notifies the overlay device of the coordinates of the mouse cursor;
If the overlay apparatus determines that the coordinates of the mouse cursor have not changed at the first time, the color of the pixel at the coordinates of the mouse cursor in the first image is a predetermined fixed color. The image display system according to claim 2, wherein it is determined whether or not. The color information of the first image is composed of one or more color elements, and a fixed value different from the value of each color element in the case of no signal is selected as the value of each color element of the fixed color And
The overlay device matches the fixed color with the color of the pixel at the coordinates of the mouse cursor in the first image that it has reconstructed before a second time shorter than the first time. 5. The image display system according to claim 4, wherein an image in which the position / size of the second image is changed is displayed on the arbitrary area on the first image by performing chroma key composition.   The base image output device divides and outputs the first image into a plurality of areas, and the mouse cursor cyclically moves in the plurality of areas every third time longer than the first time. The image display system according to claim 4, wherein the image display system is controlled so as to perform.   The image display according to claim 4, wherein the base image output device changes a design of the mouse cursor when it is determined that a mouse operation is not performed on the mouse cursor. system.

Images