Circuit arrangement and head-up display device

Abstract

Circuit device and head-up display device. The circuit device is for a head-up display device. The circuit device includes a distortion correction circuit and a detection circuit. The distortion correction circuit performs distortion correction on input image data of an input image that is image data, and outputs output image data of an output image that is image data after the distortion correction. Each first divided region of a first divided region group obtained by dividing the input image corresponds to each second divided region of a second divided region group in the output image in the distortion correction. At this time, the detection circuit compares the input image data of each first divided region with the output image data of each second divided region, thereby detecting a distortion correction error of each second divided region.

Description

Technical Field

[0001] This invention relates to circuit devices and head-up display devices, etc. Background Technology

[0002] Patent Document 1 discloses a circuit arrangement for a head-up display. This circuit arrangement 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 of the head-up display exceeds a first threshold. Upon detecting the occurrence of the first glare error, the processing circuit performs processing corresponding to the first glare error.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-101784

[0004] In a head-up display (HUD), distortion correction is performed on the image, applying a distortion opposite to that during projection, thereby projecting an undistorted image. When detecting errors in distortion correction processing, if a common error detection is performed on the entire HUD screen, there is a problem that error handling can only be applied to the entire screen. Patent Document 1 described above is an example of glare detection; however, it calculates a glare index based on the overall image data and detects the occurrence of a first glare error based on this index. That is, a common glare detection is performed on the entire HUD screen, therefore, only common error handling can be applied to the entire screen. Summary of the Invention

[0005] One aspect of the present invention relates to a circuit device for a head-up display device, wherein the circuit device comprises: a distortion correction circuit that performs distortion correction on input image data as image data of an input image and outputs output image data as image data of the distortion-corrected output image; and an error detection circuit that, when each first segmented region of a first segmented region group obtained by segmenting the input image corresponds to each second segmented region of a second segmented region group in the output image in the distortion correction, compares the input image data of each first segmented region with the output image data of each second segmented region, thereby detecting distortion correction errors in each second segmented region.

[0006] Furthermore, other aspects of the present invention relate to a head-up display device, wherein the head-up display device comprises: the circuitry described above; a processing device that controls the circuitry; and a display device that projects and displays an image based on the output image data from the circuitry. Attached Figure Description

[0007] Figure 1 This is an example of a HUD display.

[0008] Figure 2 This is a structural example of a head-up display device and its circuitry.

[0009] Figure 3 This is a diagram illustrating the operation of the error detection circuit.

[0010] Figure 4 This is a detailed structural example of the error detection department.

[0011] Figure 5 This is a diagram illustrating the operation of the error detection unit.

[0012] Figure 6 This is the first detailed structural example of a circuit device.

[0013] Figure 7 This is the second detailed structural example of a circuit device.

[0014] Figure 8 This is the third detailed structural example of a circuit device.

[0015] Figure 9 These are the fourth detailed structural example of a circuit device and a detailed structural example of a display device.

[0016] Figure 10 This is the first example of how to handle distortion correction errors in each region.

[0017] Figure 11 This is the second example of how to handle distortion correction errors in each region.

[0018] Label Explanation

[0019] 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 transformation circuit; 114: Interpolation circuit; 115: Storage circuit; 130: Output circuit; 140: Interface circuit; 160: Status register; 170: Interrupt signal generation circuit; 200: Processing device; 320: Error detection circuit; 321: Region determination unit; 322: Error determination unit; 323: Error detection coordinate transformation unit; 324: Inverse distortion correction unit; ARA: First segmented region; ARB: Second segmented region; ARH: Third segmented region; IMA: Input image data; IMB: Output image data; IRQ: Interrupt signal. Detailed Implementation

[0020] The preferred embodiments of the present invention will now be described in detail. Furthermore, the embodiments described below are not intended to unduly limit the scope of the claims, and the structures described in these embodiments are not necessarily all essential structural elements.

[0021] 1. Example of the first structure of a display system and circuit device

[0022] Figure 1 This shows an example of a HUD display. HUD is an abbreviation for Head-Up Display; hereafter, Head-Up Display will sometimes be appropriately abbreviated as HUD.

[0023] A HUD comprises a liquid crystal panel, a backlight, and a reflector. The backlight emits light, which, after passing through the liquid crystal panel, is reflected by the reflector towards the screen, and the reflected light enters the user's eyes. This projects a virtual image 6, corresponding to the object displayed on the liquid crystal panel, into the user's field of vision. This virtual image 6 overlaps with the real space that serves as the background for the HUD display. Areas within the HUD's display area 5 where the virtual image 6 is not displayed are opaque in the liquid crystal panel; therefore, they are transparent areas without any visible display, allowing the background to be directly seen.

[0024] As described above, distortion correction is performed during the image processing of the HUD. When this distortion correction results in a processing error, a display object with a different shape, size, or color than the originally intended display object 6 may be displayed, or the originally intended display object 6 may not be displayed at all. Therefore, in this embodiment, the circuitry for the HUD detects distortion correction errors. In this case, it is preferable to be able to detect which part of the distortion correction processing within the display area 5 of the HUD has resulted in an error. As an example, it is possible to consider error handling that makes the HUD display transparent when an error occurs, but from the viewpoint of continuing to provide information prompts to the user, it is preferable to maintain the HUD display as much as possible. If it is possible to detect which part of the distortion correction processing has resulted in an error, it is possible to make only the part of the HUD display where the error occurred transparent, without making the entire HUD display transparent, and to maintain the HUD display in other areas.

[0025] Figure 2 This is an example of the structure of the head-up display device 50 and the circuitry device 100 for the head-up display device 50 in this embodiment. The head-up display device 50 includes a display device 30, a circuitry device 100, and a processing device 200.

[0026] The processing device 200 sends input image data IMA, which is image data of the input image, to the circuit device 100. The processing device 200 is a so-called SoC, such as a CPU or microprocessor. SoC is an abbreviation for System on Chip. CPU is an abbreviation for Central Processing Unit.

[0027] 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 multiple circuit elements are integrated on a semiconductor substrate.

[0028] The input circuit 105 receives input image data (IMA) from the processing device 200. The input circuit 105 can also be a receiver circuit for various communication interfaces, such as LVDS, DVI, display port, GMSL, or GVIF. LVDS stands for Low Voltage Differential Signaling, DVI for Digital Visual Interface, GMSL for Gigabit Multimedia Serial Link, and GVIF for Gigabit Video Interface.

[0029] The distortion correction circuit 110 uses coordinate transformation between pixel coordinates in the input image data IMA and pixel coordinates in the output image data IMB to perform distortion correction on the input image data IMA, and outputs the result as the image data of the output image, i.e., the output image data IMB. Distortion correction is used to correct the distortion of the HUD display by applying image distortion opposite to that of the image displayed on the projection display panel, resulting in a distortion-free or distortion-reduced display. Image distortion caused by projection includes image distortion caused by the curvature of the screen, image distortion caused by the HUD optical system, or both.

[0030] The distortion correction circuit 110 is equivalent to either a reverse warp engine or a forward warp engine. Reverse warp is performed as follows: the pixel coordinates on the output image data IMB are transformed into reference coordinates corresponding to those pixel coordinates; and the pixel data of the output image data IMB is calculated based on the pixel data of the input image data IMA at those reference coordinates. Forward warp is performed as follows: the pixel coordinates on the input image data IMA are transformed into motion destination coordinates corresponding to those pixel coordinates; and the pixel data of the output image data IMB at those motion destination coordinates is calculated based on the image data of the input image data IMB at those pixel coordinates. The coordinate transformations in reverse and forward warps are defined by warp parameters. Warp parameters can be tables mapping the coordinates on the input image data IMA to the coordinates on the output image data IMB, tables representing the amount of movement between the coordinates on the input image data IMA and the coordinates on the output image data IMB, or coefficients of polynomials mapping the coordinates on the input image data IMA to the coordinates on the output image data IMB.

[0031] Furthermore, 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 can also be configured as separate circuits, or they can be integrated into a single circuit through automatic configuration wiring, etc. Moreover, some or all of these logic circuits can be implemented by a processor such as a DSP (Digital Signal Processor). In this case, a program and instruction set describing the functions of each circuit are stored in memory, and the processor executes the program and instruction set to implement the functions of each circuit.

[0032] The output circuit 130 sends output image data (IMB) to the display device 30. The output circuit 130 can also be a transmitting circuit of various communication interfaces, but as an example, it is a transmitting circuit of LVDS, DVI, display port, GMSL or GVIF, etc.

[0033] 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 structure of the display device 30 is not limited to this; for example, the circuit device 100 may have the function of a display controller built into it.

[0034] The display controller performs image data transmission and display timing control for the display driver 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 the image corresponding to the output image data (IMB). The optical system includes reflectors, etc., to project the image displayed by the image display device onto the screen. The screen can be any transparent object with a projection surface that reflects the projected light. For example, the screen is the windshield of a moving body equipped with a HUD. The image display device is, for example, a liquid crystal display panel and a backlight device. Alternatively, the image display device can be a laser light source, a reflector that reflects the laser light, and an actuator that drives the reflector in a scanning laser manner. Alternatively, the image display device can be a digital reflector device including a laser light source, an array of micro-reflectors, and actuators that drive each micro-reflector. Alternatively, the image display device can be a self-emissive display panel such as an OLED display panel. OLED is an abbreviation for Organic Light Emitting Diode.

[0035] The error detection circuit 320 of the circuit device 100 compares the input image data IMA with the output image data IMB, thereby performing distortion correction error detection. Distortion correction error detection checks whether distortion correction in the distortion correction circuit 110 has been performed correctly. However, "correct" here is not limited to the case where distortion correction is performed without error even at the single bit level; it also includes cases where the input image data IMA and the output image data IMB are approximately identical to such an extent that the input image and the HUD display image can be considered approximately the same.

[0036] Figure 3 This diagram illustrates the operation of the error detection circuit 320. The error detection circuit 320 includes a region determination unit 321 and an error determination unit 322. The dashed lines are used to indicate segmented regions and are not actually displayed.

[0037] like Figure 3 As shown, the region determination unit 321 sets a first segmented region group obtained by segmenting the input image. Each first segmented region in the first segmented region group is represented by ARA. Specifically, the segmented 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 segmented region group into the region setting register, and the region determination unit 321 sets the first segmented region group according to this setting information. Furthermore, Figure 3 An example of 6×4 segmentation of an image is shown, but the number of segments is not limited to this. Furthermore, Figure 3 The diagram shows an example of equally dividing an image in both the horizontal and vertical directions, but non-equal division is also possible. For example, the upper part of the image can be finely divided vertically, or the central part horizontally can be finely divided.

[0038] The input image is corrected for distortion in the opposite direction to that caused by HUD projection before being projected into the HUD, resulting in a distortion-free display identical to the input image. That is, setting a first segmentation region group in the input image is equivalent to setting a segmentation region group in the HUD display. This segmentation region group in the HUD display is designated as the third segmentation region group, and each third segmentation region is denoted by ARH. The shape of the third segmentation region ARH is the same as the first segmentation region ARA corresponding to it. Furthermore, the coordinates (u, v) on the input image and the coordinates (x, y) on the output image are mapped to each other through coordinate transformation for distortion correction. Through this coordinate mapping, the output image is segmented into a second segmentation region group corresponding to the first segmentation region group. Each second segmentation region in the second segmentation region group is denoted by ARB. The second segmentation region ARB becomes the shape distorted by distortion correction.

[0039] As described above, each of the first segmented regions ARA of the input image, each of the second segmented regions ARB of the output image, and each of the third segmented regions ARH displayed on the HUD are corresponding to each other. Therefore, the error detection circuit 320 compares the input image data IMA of the first segmented region ARA with the output image data IMB of the second segmented region ARB corresponding to that first segmented region ARA, thereby detecting distortion correction errors according to each of the third segmented regions ARH displayed on the HUD.

[0040] Specifically, the region determination unit 321 determines which first segmentation region (ARA) in the first segmentation region group the coordinates (u, v) on the input image corresponding to the coordinates (x, y) on the output image belong to. When multiple coordinates (u, v) corresponding to multiple coordinates (x, y) belong to the same first segmentation region (ARA), the region determination unit 321 determines that these multiple coordinates (x, y) belong to the same second segmentation region (ARB). Thus, the second segmentation region (ARB) of the output image corresponding to the first segmentation region (ARA) set in the input image can be determined. The pixel data of the input image data IMA at coordinates (u, v) is set to PA(u, v), and the pixel data of the output image data IMB at coordinates (x, y) is set to PB(x, y). The error determination unit 322 determines whether a distortion correction error has occurred in the second segmentation region (ARB) based on the pixel data PA(u, v) belonging to the first segmentation region (ARA) and the pixel data PB(x, y) belonging to the second segmentation region (ARB) corresponding to that first segmentation region (ARA). The error determination unit 322 performs the error determination on each of the second segmented regions ARB.

[0041] In this embodiment described above, the circuit device 100 is used in the 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 the input image data IMA, which is image data of the input image, and outputs output image data IMB, which is image data of the distortion-corrected output image. Each first segmented region ARA of the first segmented region group obtained by segmenting the input image corresponds to each second segmented region ARB of the second segmented region group in the output image during distortion correction. At this time, the error detection circuit 320 compares the input image data IMA of each first segmented region ARA with the output image data IMB of each second segmented region ARB, thereby detecting distortion correction errors in each second segmented region ARB.

[0042] According to this embodiment, when a distortion correction error occurs in a portion of an image, the region where the error occurred can be detected. Specifically, the input image data IMA of each first segmentation region ARA is compared with the output image data IMB of each second segmentation region ARB, thereby detecting that the first segmentation region ARA and the second segmentation region ARB, where the consistency between the two is low, are regions where distortion correction errors have occurred. Therefore, error handling can be performed only on the regions where distortion correction errors are detected. For example, such as... Figures 9-11 The processing device 200 makes the area determined to be a distortion correction error transparent, thereby making the image of the area where the distortion correction error occurred non-displayable, and maintaining the HUD display of the other areas, thereby enabling continued information prompts to the user.

[0043] Furthermore, according to this embodiment, the output image becomes an image distorted through distortion correction; therefore, a first segmentation region group is set in the undistorted input image. At this time, each first segmentation region ARA of the first segmentation region group obtained by segmenting the input image corresponds to each second segmentation region ARB of the second segmentation region group in the output image during distortion correction. Therefore, the error detection circuit 320 can use this correspondence to compare the input image data IMA of each first segmentation region ARA with the output image data IMB of each second segmentation region ARB.

[0044] Furthermore, in this embodiment, the error detection circuit 320 determines the correspondence between each first segmentation region ARA and each second segmentation region 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 corresponding after distortion correction.

[0045] According to this embodiment, the coordinate transformation during distortion correction involves a coordinate transformation between the coordinates GZA = (u, v) on the input image and the coordinates GZB = (x, y) on the output image. The error detection circuit 320 can use this correspondence to determine which first segmentation region ARA the input image coordinates GZA = (u, v) corresponding to the coordinates GZB = (x, y) on the output image belongs to. Thus, the first segmentation region ARA on the input image corresponds to the second segmentation region ARB on the output image.

[0046] 2. Detailed structural example of the error detection unit

[0047] Figure 4 This is a detailed structural example 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.

[0048] Figure 5This diagram illustrates the operation of the error detection unit 322. Here, it is assumed that n first segmentation regions ARA1 to ARA1 are defined in the input image. ARBk represents the second segmentation region corresponding to the first segmentation region ARAk. n is an integer greater than or equal to 2, and k is an integer greater than or equal to 1 and less than or equal to n.

[0049] The histogram calculation unit (HSA) calculates a histogram based on the input image data IMA of the first segmented region ARAk. The histogram displays the normalized number of pixels with each pixel value. The normalized number of pixels is obtained by dividing the number of pixels with each pixel value by the total number of pixels in the first segmented region ARAk. Figure 5 In the example, for the first segmented region ARAk, a histogram is shown, but the histogram calculation unit HSA calculates the histograms of R pixel values, G pixel values, and B pixel values.

[0050] The histogram calculation unit (HSB) calculates the histogram based on the output image data IMB of the second segmentation region ARBk. The normalized pixel count is obtained by dividing the number of pixels with each pixel value by the total number of pixels in the second segmentation region ARBk. Figure 5 In the example, for the second segmented region ARBk, one histogram is shown, but the histogram calculation unit HSB calculates the histograms of R pixel values, G pixel values, and B pixel values.

[0051] The comparison unit CP compares the histogram of the first segmented region ARAk with the histogram of the second segmented region ARBk. If the histograms of the first segmented region ARAk and the second segmented region ARBk are different, the comparison unit CP determines that an error has occurred in the distortion correction of the second segmented region ARBk. Furthermore, the similarity of histograms includes cases where the histograms are approximately the same.

[0052] Specifically, the comparison unit CP calculates the differences between the histograms of the R, G, and B pixel values ​​of the first segmented region ARAk and the histograms of the R, G, and B pixel values ​​of the second segmented region ARBk. Equation (1) below shows the mathematical expression for calculating the difference SADk.

[0053]

[0054] In equation (1) above, ARAk_rbin(i) represents the normalized number of pixels of value i in the histogram of the R pixel values ​​of the first segmented region ARAk. Here, it is assumed that i is an integer greater than 0 and less than 15. ARBk_rbin(i) represents the normalized number of pixels of value i in the histogram of the R pixel values ​​of the second segmented region ARBk. ARAk_gbin(i) represents the normalized number of pixels of value i in the histogram of the G pixel values ​​of the first segmented region ARAk. ARBk_gbin(i) represents the normalized number of pixels of value i in the histogram of the G pixel values ​​of the second segmented region ARBk. ARAk_bbin(i) represents the normalized number of pixels of value i in the histogram of the B pixel values ​​of the first segmented region ARAk. ARBk_bbin(i) represents the normalized number of pixels of value i in the histogram of the B pixel values ​​of the second segmented region ARBk.

[0055] The comparison unit CP compares the difference SADk with a threshold. If the difference SADk is greater than the threshold, it determines that a distortion correction error has occurred in the second segmentation region ARB. SADk in equation (1) is a real number greater than 0 and less than 6. When the histograms are perfectly consistent, SADk = 0. The closer SADk is to 0, the higher the consistency of the histograms. A threshold is set based on the required consistency of the histograms. For example, the processing device 200 writes the threshold into a register (not shown) set in the circuit device 100, and the comparison unit CP compares this threshold with the difference SADk.

[0056] In the above embodiment, the error detection circuit 320 compares the histogram of the pixel values ​​of the input image data IMA in each first segmentation region ARA with the histogram of the pixel values ​​of the output image data IMB in each second segmentation region ARB, thereby detecting distortion correction errors.

[0057] When a distortion correction error occurs in the second segmented region ARB, the histogram of the second segmented region ARB is inconsistent with the histogram of the first segmented region ARA corresponding to the second segmented region ARB. According to this embodiment, by comparing the histograms of each first segmented region ARA with the histograms of each second segmented region ARB, regions with inconsistent histograms can be identified as distortion correction errors. Furthermore, as mentioned above, consistency here is not limited to complete consistency.

[0058] Furthermore, in this embodiment, the error detection circuit 320 compares the histograms of the R pixel values, G pixel values, and B pixel values ​​of the input image data IMA in each first segmentation region ARA with the histograms of the R pixel values, G pixel values, and B pixel values ​​of the output image data IMB in each second segmentation region ARB, thereby detecting distortion correction errors.

[0059] According to this embodiment, the input image data IMA and the output image data IMB are compared using histograms for each of the RGB values, thereby enabling accurate error detection. For example, compared to using a histogram of luminance values, using histograms for each of the RGB values ​​allows for histogram comparison that includes not only luminance but also color information.

[0060] Furthermore, in this embodiment, the error detection circuit 320 normalizes the histogram of pixel values ​​of the input image data IMA in each first segmentation region ARA using the number of pixels in each first segmentation region ARA, and normalizes the histogram of pixel values ​​of the output image data IMB in each second segmentation region ARB using the number of pixels in each second segmentation region ARB. The error detection circuit 320 compares 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, thereby detecting distortion correction errors.

[0061] The output image data IMB is the distortion-corrected image data. Therefore, the shape of the second segmented region ARB in the output image is different from the shape of the first segmented region ARA set in the input image. Consequently, the number of pixels in the first segmented region ARA is different from the number of pixels in the second segmented region ARB. According to this embodiment, the histogram is normalized using the number of pixels in the segmented regions, thus enabling a comparison of the histogram before and after distortion correction.

[0062] 3. Detailed structural examples of circuit devices, from the first to the third detailed structural examples.

[0063] Figure 6 This is the first detailed structural example of the circuit device 100. Figure 6 In this circuit, distortion correction circuit 110 includes coordinate counter 112, coordinate transformation circuit 113, interpolation circuit 114, and storage circuit 115. Here, distortion correction circuit 110 is described as an example of a reverse distortion engine.

[0064] Coordinate counter 112 outputs the pixel coordinates GZB = (x, y) on the output image data IMB. Coordinate transformation circuit 113 converts the pixel coordinates (x, y) into reference coordinates GZA = (u, v) on the input image data IMA. Storage circuit 115 temporarily stores the input image data IMA and outputs the pixel data PXD at the reference coordinates (u, v). Specifically, coordinate transformation circuit 113 converts the reference coordinates (u, v) into a read address, and storage circuit 115 reads the pixel data PXD at the reference coordinates (u, v) from this read address. More specifically, coordinate transformation circuit 113 outputs the read addresses of multiple pixels surrounding the reference coordinates (u, v), and storage circuit 115 reads the pixel data of these multiple pixels. Interpolation circuit 114 performs interpolation processing on the multiple pixel data read corresponding to the reference coordinates (u, v), thereby obtaining the pixel data at the pixel coordinates (x, y) in the output image data IMB.

[0065] The region determination unit 321 of the error detection circuit 320 determines the first segmentation region ARA to which the reference coordinates GZA = (u, v) on the input image data IMA belong, and thereby determines the second segmentation region ARB to which the pixel coordinates (x, y) on the output image data IMB belong.

[0066] The error determination unit 322 calculates histograms based on the region determination results, using the input image data IMA of each first segmentation region ARA and the output image data IMB of each second segmentation region ARB, and compares them to determine whether each second segmentation region ARB has generated a distortion correction error.

[0067] Figure 7 This is the second detailed structural example of the circuit device 100. Figure 7 In the circuit, the error detection circuit 320 includes a region determination unit 321, an error determination unit 322, and an error detection coordinate transformation unit 323.

[0068] The error detection coordinate transformation unit 323 converts the coordinates GZB = (x, y) on the output image data IMB into coordinates GZA = (u, v) on the input image data IMA. The region determination unit 321 determines the first segmentation region ARA to which the coordinates GZA on the input image data IMA belong, based on the coordinates GZA and GZB from the error detection coordinate transformation unit 323. Furthermore, it determines the second segmentation region ARB to which the coordinates GZB on the output image data IMB belong. The error determination unit 322 calculates a histogram based on the region determination results, using the input image data IMA for each first segmentation region ARA and the output image data IMB for each second segmentation region ARB. These histograms are then compared to determine whether a distortion correction error has occurred in each second segmentation region ARB.

[0069] Figure 8 This is the third detailed structural example of the circuit device 100. Figure 8 In the circuit, the error detection circuit 320 includes a region determination unit 321, an error determination unit 322, and an inverse distortion correction unit 324.

[0070] The inverse distortion correction unit 324 performs inverse distortion correction, which is the inverse of the distortion correction performed by the distortion correction circuit 110, on the output image data IMB, thereby generating the second input image data IMA2. If the inverse distortion correction is complete, the second input image data IMA2 is identical to the input image data IMA. However, sometimes the inverse distortion correction is not complete due to interpolation or other processes; therefore, it is sufficient for the second input image data IMA2 to be approximately the same as the input image data IMA. The region determination unit 321 determines the first segmented region ARA to which the coordinate GZA2 on the second input image data IMA2 belongs. Based on the region determination result, the error determination unit 322 calculates a histogram based on the input image data IMA of each first segmented region ARA, calculates a histogram based on the second input image data IMA2 of each first segmented region ARA, and compares them. The error determination unit 322 determines whether each first segmented region ARA has generated a distortion correction error, and thereby determines whether the corresponding second segmented region ARB has generated a distortion correction error.

[0071] In the above embodiment, the circuit device 100 includes an interrupt signal generation circuit 170, which generates an interrupt signal IRQ when a distortion correction error is detected by the error detection circuit 320.

[0072] According to this embodiment, when a distortion correction error is detected by the error detection circuit 320, 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.

[0073] Furthermore, in this embodiment, the circuit device 100 includes a status register 160 that stores information indicating the second segmented region ARB in the second segmented region group where a distortion correction error has been detected.

[0074] 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 which second segmented region ARB in the second segmented region group has been found to have a distortion correction error. For example, when an external processing device 200 accesses the status register 160, it can determine which second segmented region ARB has a distortion correction error, i.e., which first segmented region ARA has a distortion correction error.

[0075] 4. Detailed structural example of the fourth circuit device

[0076] Figure 9 This is a fourth detailed structural example of the circuit device 100 and a detailed structural example of the display device 30 when using the circuit device 100 of the fourth detailed structural example. In the circuit device 100 of the fourth detailed structural example, any one of the first to third detailed structural examples described above can be combined.

[0077] 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 for illuminating the liquid crystal display panel with backlight. The processing device 200 controls the backlight device 10 by turning it on and off, or by dimming the backlight device 10.

[0078] 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.

[0079] Interface circuit 140 is a communication interface used for communication between processing device 200 and circuit device 100. Interface circuit 140 is, for example, a serial interface such as SPI or I2C. SPI is an abbreviation for Serial Peripheral Interface, and I2C is an abbreviation for Inter-Integrated Circuit.

[0080] The error detection circuit 320 writes information indicating that a distortion correction error was detected in the second segment region ARB of the second segment region group into the status register 160. The information indicating that a distortion correction error was detected in the second segment region ARB can also be information indicating the first segment region ARA corresponding to the second segment region ARB that was detected with a distortion correction error.

[0081] 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 from one or more of the second segmented regions in the second segmented region group, the interrupt signal generation circuit 170 outputs an interrupt signal IRQ to the processing device 200.

[0082] Upon receiving an interrupt signal IRQ, the processing device 200 performs distortion correction error handling. For example, upon receiving the interrupt signal IRQ, the processing device 200 may turn off the backlight of the display device 30, or it may stop the transmission of input image data IMA. Alternatively, upon receiving the interrupt signal IRQ, the processing device 200 obtains information from the status register 160 via the interface circuit 140 regarding the second segmented region ARB, indicating that a distortion correction error has been detected. Based on the obtained information, the processing device 200 performs distortion correction error handling for each region. This example will be described below.

[0083] Figure 10 This illustrates a first example of handling distortion correction errors according to each region. The processing device 200 sends input image data IMA to the circuit device 100, causing the first segmented region ARA, corresponding to the second segmented region ARB where a distortion correction error was detected, to become black data. In a HUD display based on this input image data IMA, the third segmented region ARH, corresponding to the first segmented region ARA (black data), is displayed transparently.

[0084] Figure 11 This is the second example of how to handle distortion correction errors according to each region. For example... Figure 11 As shown in the right figure, the backlight device includes an array of light-emitting elements, which consists of multiple light-emitting elements arranged in an array. Each light-emitting element is an LED or similar light-emitting element that can be independently controlled to be turned on or off. LED is an abbreviation for Light Emitting Diode. The multiple light-emitting elements are configured to illuminate the display area of ​​the display panel 20 substantially 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 segmented region ARB where a distortion correction error was detected, and turns on the other light-emitting elements. Figure 11 In the right image, black circles represent off-light-emitting elements, and white circles represent on-light-emitting elements. Therefore, the third segmented region ARH on the HUD display, corresponding to the second segmented region ARB where distortion correction errors were detected, is transparent.

[0085] In this embodiment described above, the display device 30 includes a display panel 20 and a backlight device 10 for the display panel 20. The processing device 200 controls the backlight device 10 based on the detection results of distortion correction errors.

[0086] According to this embodiment, the processing device 200 can perform error handling based on the detection result of distortion correction error output by the circuit device 100. For example, the processing device 200 may also turn off the backlight device 10 when distortion correction error occurs in one or more of the second segmented regions in the second segmented region group. Alternatively, if the backlight device has an array of light-emitting elements, the processing device 200 may also turn off the light-emitting elements corresponding to the second segmented regions where distortion correction error has occurred.

[0087] The circuit arrangement described above in this embodiment is used in a head-up display device. The circuit arrangement includes a distortion correction circuit and an error detection circuit. The distortion correction circuit corrects the distortion of input image data, which is image data of an input image, and outputs output image data as image data of a distortion-corrected output image. The error detection circuit compares the input image data of each first segmented region with the output image data of each second segmented region when each first segmented region of a first segmented region group obtained by segmenting the input image corresponds to each second segmented region of a second segmented region group in the output image during distortion correction, thereby detecting distortion correction errors in each second segmented region.

[0088] According to this embodiment, when a distortion correction error occurs in a portion of an image, the region where the error occurred can be detected. Specifically, the input image data of each first segmentation region is compared with the output image data of each second segmentation region, thereby detecting that the first and second segmentation regions with low consistency are regions where distortion correction errors have occurred. Furthermore, according to this embodiment, the output image is an image distorted due to distortion correction; therefore, a first segmentation region group is set in the undistorted input image. At this time, each first segmentation region of the first segmentation region group obtained by segmenting the input image corresponds to each second segmentation region of the second segmentation region group in the output image in distortion correction. Therefore, the error detection circuit can use this correspondence to compare the input image data of each first segmentation region with the output image data of each second segmentation region.

[0089] Furthermore, in this embodiment, the error detection circuit can also determine the correspondence between each first segmentation region and each second segmentation region based on the correspondence information between the coordinates on the input image and the coordinates on the output image, which are corresponding through distortion correction.

[0090] According to this embodiment, coordinate transformation between coordinates on the input image and coordinates on the output image is performed during the coordinate transformation for distortion correction. The error detection circuit can use this correspondence to determine which first segmentation region the coordinates on the input image corresponding to the coordinates on the output image belong to. Thus, the first segmentation region on the input image corresponds to the second segmentation region on the output image.

[0091] Furthermore, in this embodiment, the error detection circuit can also compare the histogram of the pixel values ​​of the input image data in each first segmentation region with the histogram of the pixel values ​​of the output image data in each second segmentation region, thereby detecting distortion correction errors.

[0092] When a distortion correction error occurs in the second segmentation region, the histogram of the second segmentation region is inconsistent with the histogram of the corresponding first segmentation region. According to this embodiment, by comparing the histograms of each first segmentation region with the histograms of each second segmentation region, regions with inconsistent histograms can be identified as distortion correction errors.

[0093] Furthermore, in this embodiment, the error detection circuit can also compare the histograms of the R pixel values, G pixel values, and B pixel values ​​of the input image data in each first segmentation region with the histograms of the R pixel values, G pixel values, and B pixel values ​​of the output image data in each second segmentation region, thereby detecting distortion correction errors.

[0094] According to this embodiment, the input image data and output image data are compared using histograms for each of the RGB values, thereby enabling accurate error detection. For example, compared to using a histogram of luminance values, using histograms for each of the RGB values ​​allows for the comparison of histograms by including not only luminance but also color information.

[0095] Furthermore, in this embodiment, the error detection circuit may also normalize the histogram of pixel values ​​of the input image data in each first segmentation region using the number of pixels in each first segmentation region, and normalize the histogram of pixel values ​​of the output image data in each second segmentation region using the number of pixels in each second segmentation region. The error detection circuit may also compare the normalized histogram of pixel values ​​of the input image data with the normalized histogram of pixel values ​​of the output image data to detect distortion correction errors.

[0096] The output image data is the distortion-corrected image data; therefore, the shape of the second segmented region in the output image is different from the shape of the first segmented region set in the input image. Consequently, the number of pixels in the ARA of the first segmented region is different from the number of pixels in the second segmented region. According to this embodiment, the histogram is normalized using the number of pixels in the segmented regions; therefore, the histogram can be compared before and after distortion correction.

[0097] In addition, 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.

[0098] 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.

[0099] Furthermore, in this embodiment, the circuit device may also include a status register that stores information indicating a second segmentation region in the second segmentation region group in which a distortion correction error has been detected.

[0100] According to this embodiment, when a distortion correction error is detected by the error detection circuit, the status register can store information indicating the second segmented region in the second segmented region group where the distortion correction error was detected. For example, an external processing device accesses the status register, thereby determining which second segmented region has a distortion correction error, i.e., which first segmented region has a distortion correction error.

[0101] Furthermore, the head-up display device of this embodiment includes: a circuit device as described in any one of the above; a processing device that controls the circuit device; and a display device that projects and displays an image based on output image data from the circuit device.

[0102] Furthermore, in this embodiment, the display device may also include a display panel and a backlight device for the display panel. The processing device may also control the backlight device based on the detection results of distortion correction errors.

[0103] According to this embodiment, the processing device can perform error handling based on the detection result of distortion correction errors output by the circuit device. For example, the processing device can also turn off the backlight device when distortion correction errors occur in one or more of the second segmented regions in the second segmented region group. Alternatively, if the backlight device has an array of light-emitting elements, the processing device can also turn off the light-emitting elements corresponding to the second segmented regions where distortion correction errors have occurred.

[0104] Furthermore, although this embodiment has been described in detail above, those skilled in the art should readily understand that various modifications can be made without substantially departing from the invention and its effects. Therefore, it is assumed that all such modifications are included within the scope of this invention. For example, in the specification or drawings, any term that is described at least once with a broader or synonymous term can be replaced with that different term anywhere in the specification or drawings. Moreover, all combinations of this embodiment and its modifications are also included within the scope of this invention. Furthermore, the structure and operation of circuit devices, head-up display devices, processing devices, and display systems are not limited to those described in this embodiment, and various modifications can be implemented.

Claims

1. A circuit device for a head-up display device, characterized in that, The circuit device includes: A distortion correction circuit performs distortion correction on the input image data, which is used as the input image data, and outputs the output image data as the distortion-corrected output image. as well as An error detection circuit, when each first segmented region of the first segmented region group obtained by segmenting the input image corresponds to each second segmented region of the second segmented region group in the output image during distortion correction, compares the histogram of the pixel values ​​of the input image data of each first segmented region with the histogram of the pixel values ​​of the output image data of each second segmented region, thereby detecting distortion correction errors in each second segmented region that indicate that the distortion correction has not been performed correctly. The error detection circuit determines which of the first segmentation regions in the first segmentation region group corresponds to each of the second segmentation regions based on the correspondence information between the coordinates on the input image and the coordinates on the output image corresponding to the distortion correction. Based on the result of the region determination and the comparison result, it detects which region of the displayed image on the head-up display device has not been properly distorted.

2. The circuit device according to claim 1, characterized in that, The error detection circuit compares the histograms of the R pixel values, G pixel values, and B pixel values ​​of the input image data in each of the first segmentation regions with the histograms of the R pixel values, G pixel values, and B pixel values ​​of the output image data in each of the second segmentation regions, thereby detecting the distortion correction error.

3. The circuit device according to claim 1, characterized in that, The error detection circuit normalizes the histogram of pixel values ​​of the input image data in each of the first segmentation regions using the number of pixels in each of the first segmentation regions, and normalizes the histogram of pixel values ​​of the output image data in each of the second segmentation regions using the number of pixels in each of the second segmentation regions. The normalized histogram of pixel values ​​of the input image data is compared with the normalized histogram of pixel values ​​of the output image data to detect the distortion correction error.

4. The circuit device according to claim 1, characterized in that, The circuit device includes an interrupt signal generation circuit that generates an interrupt signal when the distortion correction error is detected by the error detection circuit.

5. The circuit device according to claim 4, characterized in that, The circuit device includes a status register that stores information indicating a second segmentation region in the second segmentation region group where the distortion correction error was detected.

6. A head-up display device, characterized in that, It includes: The circuit device according to any one of claims 1 to 5; Processing device that controls the circuit device; and A display device that projects and displays an image based on the output image data from the circuitry.

7. The head-up display device according to claim 6, characterized in that, The display device includes: Display panel; and The backlight device of the display panel, The processing device controls the backlight device based on the detection results of the distortion correction error.

Images