Circuit device and head-up display device

Abstract

To provide a circuit arrangement and the like that can detect, for every division area, a distortion correction error in distortion correction of a HUD.SOLUTION: A circuit arrangement 100 is used for a head-up display device 50. The circuit arrangement 100 includes a distortion correction circuit 110 and an error detection circuit 320. The distortion correction circuit 110 performs distortion correction of input image data IMA that is image data of an input image, and outputs output image data IMB that is image data of an output image after the distortion correction. First division areas in a first division area group obtained by dividing the input image and second division areas in a second division area group in the output image correspond to each other in the distortion correction. At this time, the error detection circuit 320 compares the input image data IMA of the first division areas with the output image data IMB of the second division areas with each other to detect a distortion correction error in the second division areas.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a circuit device, a head-up display device, and the like. [Background technology]

[0002] Patent Document 1 discloses a circuit device used in a head-up display. This circuit device includes an error detection circuit and a processing circuit. The error detection circuit detects the occurrence of a first glare error when a glare index value calculated from image data for the head-up display exceeds a first threshold value. When the occurrence of the first glare error is detected, the processing circuit performs processing corresponding to the first glare error. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-101784 Summary of the Invention [Problem to be solved by the invention]

[0004] In a head-up display, a distortion correction is performed to give an image a distortion that is the opposite of the image distortion at the time of projection, thereby projecting an undistorted image. When detecting a processing error in the distortion correction, if a common error detection is performed for the entire screen of the head-up display, there is a problem that only a common error response process can be performed for the entire screen. The above-mentioned Patent Document 1 is an example of glare detection, but a glare index is calculated from image data of the entire screen, and the occurrence of a first glare error is detected based on the glare index. In other words, because a common glare detection is performed for the entire screen of the head-up display, only a common error response process can be performed for the entire screen. [Means for solving the problem]

[0005] One aspect of the present disclosure relates to a circuit device used in a head-up display device, including: a distortion correction circuit that performs distortion correction on input image data, which is image data of an input image, and outputs output image data, which is image data of an output image after the distortion correction; and an error detection circuit that, when each first divided area of ​​a first divided area group into which the input image is divided corresponds to each second divided area of ​​a second divided area group in the output image in the distortion correction, detects a distortion correction error in each second divided area by comparing the input image data of each first divided area with the output image data of each second divided area.

[0006] Another aspect of the present disclosure relates to a head-up display device including the circuit device described above, a processing device that controls the circuit device, and a display device that projects a display image based on the output image data from the circuit device. [Brief explanation of the drawings]

[0007] [Figure 1] Example of HUD display. [Figure 2] 1 shows an example of the configuration of a head-up display device and a circuit device. [Figure 3] FIG. 4 is a diagram for explaining the operation of the error detection circuit. [Figure 4] 10 shows an example of a detailed configuration of an error determination unit. [Figure 5] FIG. 4 is a diagram illustrating the operation of an error determination unit. [Figure 6] 1 shows a first detailed configuration example of a circuit device. [Figure 7] 10 shows a second detailed configuration example of a circuit device. [Figure 8] 10 shows a third detailed configuration example of a circuit device. [Figure 9] 4 shows a fourth detailed configuration example of a circuit device and a detailed configuration example of a display device. [Figure 10] A first example of processing to address distortion correction errors on a region-by-region basis. [Figure 11] A second example of processing to address distortion correction errors on a region-by-region basis. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present disclosure will be described in detail below. Note that the embodiments described below do not unduly limit the scope of the claims, and not all of the configurations described in the embodiments are necessarily essential components.

[0009] 1. First configuration example of display system and circuit device An example of a HUD display is shown in Figure 1. HUD is an abbreviation for head-up display, and in the following, head-up display may be abbreviated as HUD where appropriate.

[0010] The HUD includes a liquid crystal panel, a backlight device, and a reflector. The backlight device emits light, which passes through the liquid crystal panel and is reflected by the reflector toward a screen. The light reflected by the screen enters the user's eyes. This projects a virtual image object 6 corresponding to the object displayed on the liquid crystal panel into the user's field of vision. This virtual image object 6 is superimposed on the real space that forms the background of the HUD display. The areas within the HUD display area 5 where the virtual image object 6 is not displayed are transparent areas with no display because the liquid crystal panel is opaque, and the background is visible.

[0011] As described above, distortion correction is performed during image processing of the HUD. However, if a processing error occurs during the distortion correction, an object 6 may be displayed that is different in shape, size, or color from the object 6 that should be displayed, or the object 6 may not be displayed at all. For this reason, in this embodiment, a circuit device used in the HUD detects distortion correction errors. At this time, it is desirable to be able to detect which portion of the HUD display area 5 has experienced an error in the distortion correction process. As an example, an error response process could be implemented that makes the HUD display transparent when an error occurs. However, from the perspective of continuing to present information to the user, it is desirable to maintain the HUD display as much as possible. If it is possible to detect which portion of the distortion correction process has experienced an error, rather than making the entire HUD display transparent, it is possible to make only the portion of the HUD where the error occurred transparent and maintain the rest of the HUD display.

[0012] 2 shows an example of the configuration of a head-up display device 50 according to this embodiment and a circuit device 100 used in the head-up display device 50. The head-up display device 50 includes a display device 30, the circuit device 100, and a processing device 200.

[0013] The processing device 200 transmits input image data IMA, which is image data of an input image, to the circuit device 100. The processing device 200 is a so-called SoC, and is, for example, a processor such as a CPU or a microcomputer. SoC is an abbreviation for System on Chip. CPU is an abbreviation for Central Processing Unit.

[0014] The circuit device 100 includes an input circuit 105, a distortion correction circuit 110, an error detection circuit 320, and an output circuit 130. The circuit device 100 is, for example, an integrated circuit device in which a plurality of circuit elements are integrated on a semiconductor substrate.

[0015] The input circuit 105 receives input image data IMA from the processing device 200. The input circuit 105 may be a receiving circuit for various communication interfaces, examples of which include LVDS, DVI, DisplayPort, GMSL, and GVIF. LVDS stands for Low Voltage Differential Signaling, DVI stands for Digital Visual Interface, GMSL stands for Gigabit Multimedia Serial Link, and GVIF stands for Gigabit Video Interface.

[0016] The distortion correction circuit 110 performs distortion correction on the input image data IMA using coordinate conversion between pixel coordinates in the input image data IMA and pixel coordinates in the output image data IMB, and outputs the result as output image data IMB, which is image data for the output image. Distortion correction is image correction that applies image distortion to the image that is the opposite of the image distortion that occurs when the image displayed on the display panel is projected, thereby creating a HUD display with no or reduced distortion. Image distortion due to projection includes image distortion due to the curved surface of the screen, image distortion due to the HUD optical system, or both.

[0017] The distortion correction circuit 110 corresponds to a reverse warp engine or a forward warp engine. Reverse warp is a warp process that transforms pixel coordinates on the output image data IMB into corresponding reference coordinates and obtains pixel data on the output image data IMB from pixel data on the input image data IMA at those reference coordinates. Forward warp is a warp process that transforms pixel coordinates on the input image data IMA into corresponding destination coordinates and obtains pixel data on the output image data IMB at those destination coordinates from pixel data on the input image data IMA at those pixel coordinates. The coordinate transformations in reverse warp and forward warp are defined by warp parameters. The warp parameters are a table that associates coordinates on the input image data IMA with coordinates on the output image data IMB, a table that indicates the amount of movement between coordinates on the input image data IMA and coordinates on the output image data IMB, or polynomial coefficients that associate coordinates on the input image data IMA with coordinates on the output image data IMB.

[0018] The distortion correction circuit 110 and the error detection circuit 320 are logic circuits. The distortion correction circuit 110 and the error detection circuit 320 may each be configured as separate circuits, or the distortion correction circuit 110 and the error detection circuit 320 may be configured as an integrated circuit using automatic placement and routing or the like. Furthermore, some or all of these logic circuits may be realized by a processor such as a DSP. DSP stands for Digital Signal Processor. In this case, a program or instruction set describing the function of each circuit is stored in memory, and the function of each circuit is realized by the processor executing the program or instruction set.

[0019] The output circuit 130 transmits the output image data IMB to the display device 30. The output circuit 130 may be a transmission circuit of various communication interfaces, examples of which include LVDS, DVI, DisplayPort, GMSL, and GVIF.

[0020] The display device 30 displays a virtual image in the user's field of view based on the output image data IMB received from the circuit device 100. The display device 30 includes a display controller, a display driver, an image display device, and an optical system. However, the configuration of the display device 30 is not limited to this, and for example, the circuit device 100 may have a built-in display controller function.

[0021] The display controller transmits image data to the display driver and controls the display timing based on the received output image data IMB. The display driver drives the image display device based on the image data and display timing control from the display controller, and the image display device displays an image corresponding to the output image data IMB. The optical system includes a reflector and projects the image displayed by the image display device onto a screen. The screen may be a transparent projection target having a projection surface that reflects the projected light. For example, the screen may be a windscreen of a mobile vehicle equipped with a HUD. The image display device may be, for example, a liquid crystal display panel and a backlight device. Alternatively, the image display device may include a laser light source, a mirror that reflects the laser, and an actuator that drives the mirror to scan the laser. Alternatively, the image display device may be a digital mirror device including a laser light source, an array of micromirrors, and an actuator that drives each micromirror. Alternatively, the image display device may be a self-luminous display panel such as an OLED display panel. OLED stands for Organic Light Emitting Diode.

[0022] The error detection circuit 320 of the circuit device 100 detects errors in distortion correction by comparing the input image data IMA and the output image data IMB. Detecting errors in distortion correction means detecting whether distortion correction in the distortion correction circuit 110 was performed normally. However, "normal" here does not only mean that distortion correction was performed without a single bit of error, but also includes cases where the input image data IMA and the output image data IMB match to the extent that the input image and the image displayed on the HUD can be considered to be substantially identical.

[0023] 3 is a diagram illustrating the operation of error detection circuit 320. Error detection circuit 320 includes area determination unit 321 and error determination unit 322. Note that dotted lines are added to indicate divided areas and are not actually displayed.

[0024] As shown in FIG. 3, the region determination unit 321 sets a first group of divided regions by dividing the input image. Each first divided region in the first group of divided regions is indicated by ARA. Specifically, the divided regions are set by multiple straight lines in the horizontal scanning direction and multiple straight lines in the vertical direction. The circuit device 100 includes a region setting register (not shown). The processing device 200 writes setting information for the first group of divided regions to the region setting register, and the region determination unit 321 sets the first group of divided regions based on the setting information. Note that while FIG. 3 shows an example in which the image is divided into 6x4 regions, the number of divisions is not limited to this. Also, while FIG. 3 shows an example in which the image is divided evenly in the horizontal and vertical directions, it may be divided unevenly. For example, the upper part of the screen may be divided into finer vertical divisions, or the central part of the screen may be divided into finer horizontal divisions.

[0025] The input image is corrected for distortion in the opposite direction to that caused by HUD projection, and then projected onto the HUD, resulting in a display without distortion similar to the input image. In other words, setting a first group of divided areas in the input image is equivalent to setting a group of divided areas in the HUD display. This group of divided areas in the HUD display is referred to as a third group of divided areas, and each third group of divided areas is indicated by ARH. The shape of the third group of divided areas ARH is the same as the first group of divided areas ARA corresponding to that third group of divided areas ARH. Furthermore, the coordinates (u, v) on the input image and the coordinates (x, y) on the output image are associated by coordinate transformation for distortion correction. This association of coordinates divides the output image into a second group of divided areas corresponding to the first group of divided areas. Each second group of divided areas in the second group of divided areas is indicated by ARB. The second group of divided areas ARB has a distorted shape due to distortion correction.

[0026] As described above, each first divided area ARA of the input image, each second divided area ARB of the output image, and each third divided area ARH of the HUD display are associated with one another. This allows the error detection circuit 320 to detect a distortion correction error for each third divided area ARH of the HUD display by comparing the input image data IMA of the first divided area ARA with the output image data IMB of the second divided area ARB corresponding to that first divided area ARA.

[0027] Specifically, the area determination unit 321 determines which first divided area ARA of the first divided area group a coordinate (u, v) in the input image corresponding to a coordinate (x, y) in the output image belongs to. When multiple coordinates (u, v) corresponding to multiple coordinates (x, y) belong to the same first divided area ARA, the area determination unit 321 determines that the multiple coordinates (x, y) belong to the same second divided area ARB. In this way, the second divided area ARB of the output image corresponding to the first divided area ARA set in the input image is determined. The pixel data of the input image data IMA at the coordinate (u, v) is defined as PA(u, v), and the pixel data of the output image data IMB at the coordinate (x, y) is defined as PB(x, y). The error determination unit 322 determines whether a distortion correction error has occurred in the second divided area ARB based on the pixel data PA(u, v) belonging to the first divided area ARA and the pixel data PB(x, y) belonging to the second divided area ARB corresponding to the first divided area ARA. The error determination unit 322 performs this error determination for each second divided area ARB.

[0028] In the above-described embodiment, the circuit device 100 is used in a head-up display device 50. The circuit device 100 includes a distortion correction circuit 110 and an error detection circuit 320. The distortion correction circuit 110 performs distortion correction on input image data IMA, which is image data of an input image, and outputs output image data IMB, which is image data of an output image after the distortion correction. Each first divided area ARA of the first divided area group obtained by dividing the input image corresponds to each second divided area ARB of the second divided area group in the output image in terms of distortion correction. At this time, the error detection circuit 320 detects a distortion correction error in each second divided area ARB by comparing the input image data IMA of each first divided area ARA with the output image data IMB of each second divided area ARB.

[0029] According to this embodiment, when a distortion correction error occurs in a portion of an image, the area where the error occurred can be detected. Specifically, by comparing the input image data IMA of each first divided area ARA with the output image data IMB of each second divided area ARB, the first divided area ARA and the second divided area ARB where the degree of match is low are detected as areas where a distortion correction error occurred. This makes it possible to perform error handling processing only on areas where a distortion correction error has been detected. For example, as will be described later with reference to FIGS. 9 to 11, the processing device 200 displays areas determined to have a distortion correction error transparently, thereby hiding the image of the area where the distortion correction error occurred while maintaining the HUD display of the other areas, thereby allowing information to continue to be presented to the user.

[0030] Furthermore, according to this embodiment, since the output image is a distorted image due to distortion correction, the first division area group is set to the undistorted input image. At this time, each first division area ARA of the first division area group obtained by dividing the input image corresponds to each second division area ARB of the second division area group in the output image in terms of distortion correction, so the error detection circuit 320 can use this correspondence to compare the input image data IMA of each first division area ARA with the output image data IMB of each second division area ARB.

[0031] In addition, in this embodiment, the error detection circuit 320 determines the correspondence between each first divided area ARA and each second divided area ARB based on the correspondence information between the coordinates GZA=(u,v) on the input image and the coordinates GZB=(x,y) on the output image, which are matched by distortion correction.

[0032] According to this embodiment, the coordinate transformation for distortion correction involves a coordinate transformation between the coordinate GZA=(u,v) on the input image and the coordinate GZB=(x,y) on the output image. Using this correspondence, the error detection circuit 320 can determine to which first division area ARA the coordinate GZA=(u,v) on the input image corresponding to the coordinate GZB=(x,y) on the output image belongs. This allows the first division area ARA on the input image to correspond to the second division area ARB on the output image.

[0033] 2. Detailed configuration example of error detection unit 4 shows an example of a detailed configuration of the error determination unit 322. The error determination unit 322 includes a histogram calculation unit HSA, a histogram calculation unit HSB, and a comparison unit CP.

[0034] 5 is a diagram illustrating the operation of the error determination unit 322. Here, it is assumed that n first division areas ARA1 to ARAn are set in the input image. A second division area corresponding to a first division area ARAk is indicated by ARBk. n is an integer equal to or greater than 2, and k is an integer equal to or greater than 1 and equal to or less than n.

[0035] The histogram calculation unit HSA calculates a histogram from the input image data IMA of the first divided area ARAk. The histogram shows the normalized number of pixels having each pixel value. The normalized number of pixels is the number of pixels having each pixel value divided by the total number of pixels in the first divided area ARAk. While FIG. 5 shows one histogram for the first divided area ARAk, the histogram calculation unit HSA calculates a histogram of R pixel values, a histogram of G pixel values, and a histogram of B pixel values.

[0036] The histogram calculation unit HSB calculates a histogram from the output image data IMB of the second divided area ARBk. The normalized pixel number is the number of pixels having each pixel value divided by the total number of pixels in the second divided area ARBk. While Fig. 5 shows one histogram for the second divided area ARBk, the histogram calculation unit HSB calculates a histogram of R pixel values, a histogram of G pixel values, and a histogram of B pixel values.

[0037] The comparison unit CP compares the histogram of the first divided area ARAk with the histogram of the second divided area ARBk. If the histograms of the first divided area ARAk and the second divided area ARBk are not identical, the comparison unit CP determines that an error has occurred in the distortion correction of the second divided area ARBk. Note that the histograms being identical also include the case where the histograms are approximately identical.

[0038] Specifically, the comparison unit CP calculates the difference between the histogram of R pixel values, the histogram of G pixel values, and the histogram of B pixel values ​​of the first divided area ARAk and the histogram of R pixel values, the histogram of G pixel values, and the histogram of B pixel values ​​of the second divided area ARBk. The formula for calculating the difference SADk is shown in the following equation (1).

[0039]

number

[0040] In the above equation (1), ARAk_rbin(i) indicates the normalized pixel count for pixel value i in the histogram of R pixel values ​​of the first divided region ARAk. Here, i is an integer between 0 and 15. ARBk_rbin(i) indicates the normalized pixel count for pixel value i in the histogram of R pixel values ​​of the second divided region ARBk. ARAk_gbin(i) indicates the normalized pixel count for pixel value i in the histogram of G pixel values ​​of the first divided region ARAk. ARBk_gbin(i) indicates the normalized pixel count for pixel value i in the histogram of G pixel values ​​of the second divided region ARBk. ARAk_bbin(i) indicates the normalized pixel count for pixel value i in the histogram of B pixel values ​​of the first divided region ARAk. ARBk_bbin(i) indicates the normalized pixel count for pixel value i in the histogram of B pixel values ​​of the second divided region ARBk.

[0041] The comparison unit CP compares the difference SADk with a threshold value, and if the difference SADk is greater than the threshold value, it determines that a distortion correction error has occurred in that second divided area ARB. SADk in the above formula (1) is a real number between 0 and 6, and if the histograms match perfectly, SADk = 0. The closer SADk is to 0, the higher the degree of histogram match. The threshold value is set according to the required degree of histogram match. For example, the processing device 200 writes a threshold value to a register (not shown) provided in the circuit device 100, and the comparison unit CP compares the difference SADk with that threshold value.

[0042] In the above embodiment, the error detection circuit 320 detects distortion correction errors by comparing the histogram of pixel values ​​of the input image data IMA in each first divided area ARA with the histogram of pixel values ​​of the output image data IMB in each second divided area ARB.

[0043] If a distortion correction error occurs in the second divided area ARB, the histogram of that second divided area ARB will not match the histogram of the corresponding first divided area ARA. According to this embodiment, by comparing the histogram of each first divided area ARA with the histogram of each second divided area ARB, it is possible to determine an area where they do not match as a distortion correction error. Note that, as mentioned above, this match is not limited to a perfect match.

[0044] In addition, in this embodiment, the error detection circuit 320 detects distortion correction errors by comparing the histogram of R pixel values, histogram of G pixel values, and histogram of B pixel values ​​of the input image data IMA in each first divided area ARA with the histogram of R pixel values, histogram of G pixel values, and histogram of B pixel values ​​of the output image data IMB in each second divided area ARB.

[0045] According to this embodiment, accurate error detection is possible by comparing the input image data IMA and the output image data IMB using histograms for each of RGB. For example, compared to using a histogram of brightness values, using a histogram for each of RGB allows the histograms to be compared based on not only brightness but also color information.

[0046] In this embodiment, the error detection circuit 320 normalizes the histogram of pixel values ​​of the input image data IMA in each first divided area ARA by the number of pixels in that first divided area ARA, and normalizes the histogram of pixel values ​​of the output image data IMB in each second divided area ARB by the number of pixels in that second divided area ARB. The error detection circuit 320 detects distortion correction errors by comparing the histogram of pixel values ​​of the normalized input image data IMA with the histogram of pixel values ​​of the normalized output image data IMB.

[0047] Because the output image data IMB is image data after distortion correction, the shape of the second divided area ARB in the output image is different from the shape of the first divided area ARA set in the input image. Therefore, the number of pixels in the first divided area ARA is different from the number of pixels in the second divided area ARB. According to this embodiment, the histogram is normalized by the number of pixels in the divided areas, making it possible to compare the histograms before and after distortion correction.

[0048] 3. First to third detailed configuration examples of the circuit device Fig. 6 shows a first detailed configuration example of the circuit device 100. In Fig. 6, the distortion correction circuit 110 includes a coordinate counter 112, a coordinate conversion circuit 113, an interpolation circuit 114, and a memory circuit 115. Here, an example will be described in which the distortion correction circuit 110 is a reverse warp engine.

[0049] The coordinate counter 112 outputs pixel coordinates GZB=(x,y) on the output image data IMB. The coordinate conversion circuit 113 converts the pixel coordinates (x,y) into reference coordinates GZA=(u,v) on the input image data IMA. The memory circuit 115 temporarily stores the input image data IMA and outputs pixel data PXD of the reference coordinates (u,v). Specifically, the coordinate conversion circuit 113 converts the reference coordinates (u,v) into a read address, and the memory circuit 115 reads the pixel data PXD of the reference coordinates (u,v) from the read address. More specifically, the coordinate conversion circuit 113 outputs read addresses of multiple pixels around the reference coordinates (u,v), and the memory circuit 115 reads the pixel data of the multiple pixels. The interpolation circuit 114 interpolates the multiple pixel data read corresponding to the reference coordinates (u,v) to obtain pixel data of the pixel coordinates (x,y) in the output image data IMB.

[0050] The area determination unit 321 of the error detection circuit 320 determines the first divided area ARA to which the reference coordinate GZA=(u,v) on the input image data IMA belongs, and thereby determines the second divided area ARB to which the pixel coordinate (x,y) on the output image data IMB belongs.

[0051] Based on the area determination result, the error determination unit 322 calculates a histogram from the input image data IMA of each first divided area ARA, calculates a histogram from the output image data IMB of each second divided area ARB, and compares them to determine whether a distortion correction error has occurred in each second divided area ARB.

[0052] 7 shows a second detailed configuration example of the circuit device 100. In FIG. 7, the error detection circuit 320 includes an area determination unit 321, an error determination unit 322, and an error detection coordinate conversion unit 323.

[0053] The error detection coordinate conversion unit 323 converts the coordinate GZB=(x,y) on the output image data IMB into the coordinate GZA=(u,v) on the input image data IMA. The area determination unit 321 determines the first divided area ARA to which the coordinate GZA on the input image data IMA belongs, based on the coordinates GZA and GZB from the error detection coordinate conversion unit 323, and thereby determines the second divided area ARB to which the coordinate GZB on the output image data IMB belongs. Based on the area determination result, the error determination unit 322 calculates a histogram from the input image data IMA of each first divided area ARA, calculates a histogram from the output image data IMB of each second divided area ARB, and compares them to determine whether a distortion correction error has occurred in each second divided area ARB.

[0054] 8 shows a third detailed configuration example of the circuit device 100. In FIG. 8, the error detection circuit 320 includes an area determination unit 321, an error determination unit 322, and an inverse distortion correction unit 324.

[0055] The inverse distortion correction unit 324 generates second input image data IMA2 by performing inverse distortion correction, which is the inverse of the distortion correction performed by the distortion correction circuit 110, on the output image data IMB. If the inverse distortion correction is a perfect inverse correction, the second input image data IMA2 will match the input image data IMA. However, since the inverse distortion correction may not be a perfect inverse correction due to interpolation processing, etc., the second input image data IMA2 only needs to be approximately identical to the input image data IMA. The area determination unit 321 determines the first divided area ARA to which the coordinate GZA2 on the second input image data IMA2 belongs based on the area determination result. The error determination unit 322 calculates a histogram from the input image data IMA of each first divided area ARA, calculates a histogram from the second input image data IMA2 of each first divided area ARA, and compares them. The error determination unit 322 determines whether a distortion correction error has occurred in each first divided area ARA, and thereby determines whether a distortion correction error has occurred in each corresponding second divided area ARB.

[0056] In the present embodiment described above, the circuit device 100 includes the interrupt signal generation circuit 170 that generates an interrupt signal IRQ when the error detection circuit 320 detects a distortion correction error.

[0057] According to this embodiment, when the error detection circuit 320 detects a distortion correction error, the interrupt signal generation circuit 170 generates an interrupt signal IRQ, thereby notifying the external processing device 200 that a distortion correction error has occurred.

[0058] In this embodiment, the circuit device 100 also includes a status register 160 that stores information indicating the second divided area ARB in which a distortion correction error has been detected among the second divided area group.

[0059] According to this embodiment, when a distortion correction error is detected by the error detection circuit 320, the status register 160 can store information indicating the second divided area ARB in which the distortion correction error was detected among the second divided areas. For example, the external processing device 200 can access the status register 160 to determine in which second divided area ARB the distortion correction error occurred, i.e., in which first divided area ARA the distortion correction error occurred.

[0060] 4. Fourth detailed configuration example of circuit device 9 shows a fourth detailed configuration example of the circuit device 100 and a detailed configuration example of the display device 30 when the circuit device 100 of the fourth detailed configuration example is used. The circuit device 100 of the fourth detailed configuration example can be combined with any of the first to third detailed configuration examples described above.

[0061] The display device 30 includes a display panel 20 and a backlight device 10. The display panel 20 is a liquid crystal display panel. The backlight device 10 is a device that irradiates the liquid crystal display panel with backlight. The processing device 200 controls the turning on and off of the backlight device 10 and controls the dimming of the backlight device 10.

[0062] The circuit device 100 includes an input circuit 105 , a distortion correction circuit 110 , an error detection circuit 320 , an output circuit 130 , an interface circuit 140 , a status register 160 , and an interrupt signal generation circuit 170 .

[0063] The interface circuit 140 is a communication interface for the processing device 200 to communicate with the circuit device 100. The interface circuit 140 is a serial interface such as an SPI standard or an I2C standard. SPI stands for Serial Peripheral Interface, and I2C stands for Inter-Integrated Circuit.

[0064] The error detection circuit 320 writes information indicating the second divided area ARB in which the distortion correction error was detected, among the second divided area group, to the status register 160. The information indicating the second divided area ARB in which the distortion correction error was detected may be information indicating the first divided area ARA corresponding to the second divided area ARB in which the distortion correction error was detected.

[0065] When the error detection circuit 320 detects a distortion correction error, the interrupt signal generation circuit 170 outputs an interrupt signal IRQ to the processing device 200. Specifically, when a distortion correction error is detected in one or more second divided areas of the second divided area group, the interrupt signal generation circuit 170 outputs the interrupt signal IRQ to the processing device 200.

[0066] When the processing device 200 receives the interrupt signal IRQ, it performs processing to address the distortion correction error. For example, when the processing device 200 receives the interrupt signal IRQ, it may turn off the backlight device of the display device 30 or stop transmitting the input image data IMA. Alternatively, when the processing device 200 receives the interrupt signal IRQ, it obtains information indicating the second divided region ARB in which the distortion correction error was detected from the status register 160 via the interface circuit 140. The processing device 200 performs processing to address the distortion correction error for each region based on the obtained information. An example of this processing will be described below.

[0067] 10 shows a first example of processing for dealing with distortion correction errors for each region. The processing device 200 transmits input image data IMA, in which the first divided region ARA corresponding to the second divided region ARB in which the distortion correction error was detected is displayed as black data, to the circuit device 100. In the HUD display based on this input image data IMA, the third divided region ARH corresponding to the first divided region ARA of black data is displayed as transparent.

[0068] FIG. 11 shows a second example of processing for dealing with distortion correction errors for each region. As shown in the right diagram of FIG. 11, the backlight device includes a light-emitting element array, which is composed of multiple light-emitting elements arranged in an array. Each light-emitting element is a light-emitting element, such as an LED, that can be independently turned on or off. LED stands for Light Emitting Diode. The multiple light-emitting elements are arranged so that the display region of the display panel 20 is illuminated approximately uniformly when all of them are lit. The processing device 200 turns off the light-emitting elements in the light-emitting element array that illuminate the second divided region ARB in which a distortion correction error was detected, and turns on the other light-emitting elements. In the right diagram of FIG. 11, the turned-off light-emitting elements are indicated by black circles, and the lit light-emitting elements are indicated by white circles. As a result, the third divided region ARH on the HUD display corresponding to the second divided region ARB in which a distortion correction error was detected becomes transparent.

[0069] In the above-described embodiment, the display device 30 includes the display panel 20 and the backlight device 10 for the display panel 20. The processing device 200 controls the backlight device 10 based on the detection result of the distortion correction error.

[0070] According to this embodiment, the processing device 200 can execute error handling processing based on the distortion correction error detection result output by the circuit device 100. For example, the processing device 200 may turn off the backlight device 10 when a distortion correction error occurs in one or more second divided areas of the second divided area group. Alternatively, if the backlight device has a light-emitting element array, the processing device 200 may turn off the light-emitting elements corresponding to the second divided area in which the distortion correction error occurred.

[0071] The circuit device of the present embodiment described above is used in a head-up display device. The circuit device includes a distortion correction circuit and an error detection circuit. The distortion correction circuit performs distortion correction on input image data, which is image data of an input image, and outputs output image data, which is image data of an output image after the distortion correction. When each first divided area of ​​a first divided area group obtained by dividing the input image corresponds to each second divided area of ​​a second divided area group in the output image in terms of distortion correction, the error detection circuit detects a distortion correction error in each second divided area by comparing the input image data of each first divided area with the output image data of each second divided area.

[0072] According to this embodiment, when a distortion correction error occurs in a part of an image, the area where the error occurred can be detected. Specifically, by comparing the input image data of each first division area with the output image data of each second division area, the first division area and the second division area with a low degree of match are detected as areas where a distortion correction error occurred. Furthermore, according to this embodiment, since the output image is an image distorted by distortion correction, a first division area group is set in the undistorted input image. In this case, each first division area of ​​the first division area group obtained by dividing the input image corresponds to each second division area of ​​the second division area group in the output image in terms of distortion correction, so the error detection circuit can compare the input image data of each first division area with the output image data of each second division area using this correspondence.

[0073] In this embodiment, the error detection circuit may determine the correspondence between each of the first divided regions and each of the second divided regions based on correspondence information between coordinates on the input image and coordinates on the output image that are associated by distortion correction.

[0074] According to this embodiment, a coordinate transformation between coordinates on the input image and coordinates on the output image is performed in the coordinate transformation for distortion correction. The error detection circuit uses this correspondence to determine to which first divided area the coordinates on the input image corresponding to the coordinates on the output image belong. This allows the first divided area on the input image to correspond to the second divided area on the output image.

[0075] In addition, in this embodiment, the error detection circuit may detect distortion correction errors by comparing a histogram of pixel values ​​of input image data in each first divided area with a histogram of pixel values ​​of output image data in each second divided area.

[0076] If a distortion correction error occurs in a second divided region, the histogram of that second divided region will not match the histogram of the corresponding first divided region. According to this embodiment, by comparing the histogram of each first divided region with the histogram of each second divided region, it is possible to determine that a distortion correction error has occurred in the region where the histograms do not match.

[0077] In addition, in this embodiment, the error detection circuit may detect distortion correction errors by comparing a histogram of R pixel values, a histogram of G pixel values, and a histogram of B pixel values ​​of the input image data in each first divided region with a histogram of R pixel values, a histogram of G pixel values, and a histogram of B pixel values ​​of the output image data in each second divided region.

[0078] According to this embodiment, accurate error detection is possible by comparing input image data with output image data using histograms for each of RGB. For example, compared to using a histogram of brightness values, using a histogram for each of RGB allows the histograms to be compared based on not only brightness but also color information.

[0079] In this embodiment, the error detection circuit may normalize a histogram of pixel values ​​of the input image data in each first divided region by the number of pixels in that first divided region, and may normalize a histogram of pixel values ​​of the output image data in each second divided region by the number of pixels in that second divided region. The error detection circuit may detect a distortion correction error by comparing the histogram of pixel values ​​of the normalized input image data with the histogram of pixel values ​​of the normalized output image data.

[0080] Because the output image data is image data after distortion correction, the shape of the second divided area in the output image is different from the shape of the first divided area set in the input image. Therefore, the number of pixels in the first divided area ARA is different from the number of pixels in the second divided area. According to this embodiment, the histogram is normalized by the number of pixels in the divided area, making it possible to compare the histograms before and after distortion correction.

[0081] In this embodiment, the circuit device may also include an interrupt signal generation circuit that generates an interrupt signal when a distortion correction error is detected by the error detection circuit.

[0082] According to this embodiment, when a distortion correction error is detected by the error detection circuit, the interrupt signal generation circuit generates an interrupt signal, thereby notifying an external processing device that a distortion correction error has occurred.

[0083] In this embodiment, the circuit device may also include a status register that stores information indicating a second divided area in the second divided area group in which a distortion correction error has been detected.

[0084] According to this embodiment, when a distortion correction error is detected by the error detection circuit, the status register can store information indicating which second divided area of ​​the second divided area group in which the distortion correction error was detected. For example, an external processing device can access the status register to determine in which second divided area the distortion correction error occurred, i.e., in which first divided area the distortion correction error occurred.

[0085] The head-up display device of this embodiment also includes any of the circuit devices described above, a processing device that controls the circuit device, and a display device that projects a display image based on output image data from the circuit device.

[0086] In this embodiment, the display device may include a display panel and a backlight device for the display panel. The processing device may control the backlight device based on the detection result of the distortion correction error.

[0087] According to this embodiment, the processing device can execute error handling processing based on the distortion correction error detection result output by the circuit device. For example, the processing device may turn off the backlight device when a distortion correction error occurs in one or more second divided areas of the second divided area group. Alternatively, if the backlight device has a light-emitting element array, the processing device may turn off the light-emitting element corresponding to the second divided area in which the distortion correction error occurred.

[0088] Although the present embodiment has been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure. For example, a term described at least once in the specification or drawings together with a different term having a broader or equivalent meaning may be replaced with that different term anywhere in the specification or drawings. Furthermore, all combinations of the present embodiment and modifications are also included within the scope of the present disclosure. Furthermore, the configurations and operations of the circuit device, head-up display device, processing device, display system, and the like are not limited to those described in the present embodiment, and various modifications are possible. [Explanation of symbols]

[0089] 5...display area, 6...display object, 10...backlight device, 20...display panel, 30...display device, 50...head-up display device, 100...circuit device, 105...input circuit, 110...distortion correction circuit, 112...coordinate counter, 113...coordinate conversion circuit, 114...interpolation circuit, 115...memory circuit, 130...output circuit, 140...interface circuit, 160...status register, 170...interrupt signal generation circuit, 200...processing device, 320...error detection circuit, 321...area determination unit, 322...error determination unit, 323...coordinate conversion unit for error detection, 324...inverse distortion correction unit, ARA...first divided area, ARB...second divided area, ARH...third divided area, IMA...input image data, IMB...output image data, IRQ...interrupt signal

Claims

1. A circuit device used in a head-up display device, a distortion correction circuit that performs distortion correction on input image data that is image data of an input image, and outputs output image data that is image data of an output image after the distortion correction; an error detection circuit that, when each first divided area of ​​a first divided area group obtained by dividing the input image corresponds to each second divided area of ​​a second divided area group in the output image in the distortion correction, detects a distortion correction error indicating that the distortion correction in each second divided area has not been performed normally by comparing the input image data of each first divided area with the output image data of each second divided area; Including, The distortion correction circuit In the distortion correction, a coordinate conversion is performed between coordinates on the input image and coordinates on the output image; The error detection circuit performing area determination to determine which of the first divided areas in the first divided area group each of the second divided areas corresponds to, based on correspondence information indicating correspondence between coordinates on the input image and coordinates on the output image in the coordinate transformation; A circuit device characterized in that it detects in which area of ​​the display image of the head-up display device the distortion correction is not being performed normally, based on the result of the area determination and the result of the comparison.

2. A circuit device used in a head-up display device, a distortion correction circuit that performs distortion correction on input image data that is image data of an input image, and outputs output image data that is image data of an output image after the distortion correction; an error detection circuit that, when each first divided area of ​​a first divided area group obtained by dividing the input image corresponds to each second divided area of ​​a second divided area group in the output image in the distortion correction, detects a distortion correction error indicating that the distortion correction of each second divided area has not been performed normally by comparing the input image data of each first divided area with the output image data of each second divided area; Including, The error detection circuit A circuit device characterized in that the distortion correction error is detected by comparing a histogram of pixel values ​​of the input image data in each of the first divided regions with a histogram of pixel values ​​of the output image data in each of the second divided regions.

3. 3. The circuit device according to claim 2, The error detection circuit A circuit device characterized in that the distortion correction error is detected by comparing histograms of R pixel values, histograms of G pixel values, and histograms of B pixel values ​​of the input image data in each of the first divided regions and the output image data in each of the second divided regions.

4. 4. The circuit device according to claim 2, The error detection circuit A circuit device characterized in that the distortion correction error is detected by normalizing a histogram of pixel values ​​of the input image data in each of the first divided regions by the number of pixels in each of the first divided regions, normalizing a histogram of pixel values ​​of the output image data in each of the second divided regions by the number of pixels in each of the second divided regions, and comparing the normalized histogram of pixel values ​​of the input image data with the normalized histogram of pixel values ​​of the output image data.

5. 5. The circuit device according to claim 1, A circuit device characterized by including an interrupt signal generation circuit that generates, when the distortion correction error is detected by the error detection circuit, an interrupt signal so that a processing device that transmits the input image data to the circuit device can perform processing to deal with the distortion correction error.

6. 6. The circuit device according to claim 5, A circuit device comprising: a status register that stores information indicating a second divided area in which a distortion correction error has been detected among the second divided area group.

7. A circuit arrangement according to any one of claims 1 to 6; a processing device that controls the circuit device; a display device that projects a display image based on the output image data from the circuit device; A head-up display device comprising:

8. The head-up display device according to claim 7, The display device includes: A display panel; a backlight device for the display panel; Including, The processing device includes: a head-up display device that controls the backlight device based on the detection result of the distortion correction error;

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