KR101979569B1 - Apparatus and method for correcting external images in head up display system - Google Patents

Abstract

An apparatus and method for correcting an external image of a HUD system are provided. The external image correction device of the HUD system according to an embodiment of the present invention is an external image correction device of the HUD system for producing a virtual image in front of a driver by head-up displaying an image outside the vehicle, An image acquiring unit acquiring an image; An image analyzer for analyzing the brightness of the external image; A correction determining unit for determining whether brightness correction of the external image is necessary; And an image correction unit for correcting brightness of the external image.

Description

[0001] APPARATUS AND METHOD FOR CORRECTING EXTERNAL IMAGES IN HEAD UP DISPLAY SYSTEM [0002]

The present invention relates to an apparatus and method for correcting an external image of a HUD system, and more particularly, to an apparatus and method for correcting an external image of an HUD system, in which an external image is displayed in black as the darkness becomes darker, And more particularly to an apparatus and method for correcting an external image of a HUD system.

In general, automobiles have become an indispensable product in modern society because advanced technology has been applied to improve mobility and usability. In recent years, a head-up display (HUD) has been used to project information to the driver's eyes.

The head-up display (HUD) is a system that uses a mirror to enlarge the external image information such as vehicle speed, flow rate, vehicle information, night vision image and rear surveillance camera image by a lens, And is projected on the front window of the vehicle so that the driver can recognize easily while looking at the front, thereby ensuring safety.

Generally, when driving at a speed of about 100 km / h, there is a risk of a car accident because the driver moves his / her field of view to the road and moves the vehicle about 55 meters (about 2 seconds) to move the view to the road. One of the ways to reduce this risk has been proposed a vehicle head-up display (HUD) technology, and research and development thereof has been actively conducted.

Such a head-up display device for a vehicle displays various kinds of information such as driving information and image information on a main visual line of a driver of a wind shield of the vehicle, so that the driver can easily dispatch information related to the vehicle while driving. This allows the driver to operate safely by recognizing various information related to the vehicle without taking his eyes off the road.

However, in the case of an image which is inputted from a night vision, a rear camera or the like and heads up, the display device is displayed in black as the external image is darker, so that the image of the HUD (head up display) So that the distorted information can be transmitted to the driver.

FIG. 1A is a view showing a display image in which vehicle information is displayed by a display device, and FIG. 1B is a view showing a HUD image in which a display image of FIG. 1A is displayed by a head up display device.

1A and 1B, in the case of the general image 11 displayed in black when the vehicle information such as the speed and flow rate of the vehicle is displayed on the general display device, The HUD image 12, which is a virtual image, is displayed in a transparent state when the mirror is projected onto the windshield of the vehicle.

FIG. 2A is a view showing a night vision image obtained by photographing the front side of a vehicle with a night vision device, and FIG. 2B is a view showing a rear camera image obtained by photographing the rear side of the vehicle with a rear camera.

As shown in Figs. 2A and 2B, the night vision image 16 is photographed at night and is displayed in black. In addition, when the rear camera image 17 is photographed at night, it is displayed in black, and even when photographed in the daytime, the resolution is often low and many black images are displayed. When the external image such as the night vision image 16 or the backward camera image 17 displayed in black is displayed as the HUD image by the head-up display device, the HUD image is displayed in a transparent manner as described above.

Therefore, it is necessary to calibrate the brightness of the external image in advance in order to prevent the output of the HUD image, which may represent the dark part transparently and convey the distorted information.

The present invention provides an apparatus and method for correcting an external image of a HUD system that analyzes and corrects brightness of an external image input to the HUD system and displays a HUD image based on the corrected image, will be.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided an apparatus for correcting an external image of a HUD system, the apparatus comprising: An image acquiring unit for acquiring an external image by photographing the outside of the image capturing apparatus; An image analyzer for analyzing the brightness of the external image; A correction determining unit for determining whether brightness correction of the external image is necessary; And an image correction unit for correcting brightness of the external image.

According to another aspect of the present invention, there is provided an external image correction method of an HUD system for generating a virtual image in front of a driver by head-up displaying an external image, Capturing an external image of the subject; Analyzing brightness of the external image; Determining whether correction of the external image is necessary; And correcting the external image by compensating the gamma table when correction is required.

Other specific details of the invention are included in the detailed description and drawings.

According to the present invention, the HUD image can be prevented from being displayed transparently by analyzing and correcting the brightness of an external image input to the HUD system and displaying the HUD image based on the corrected image.

In addition, by displaying the HUD image more accurately, it is possible to transmit accurate information instead of distorted information, thereby preventing danger such as a vehicle accident.

1A is a view showing a display image in which vehicle information is displayed by a display device.
FIG. 1B is a diagram illustrating a HUD image in which the display image of FIG. 1A is displayed by a head-up display device.
2A is a diagram showing a night vision image obtained by photographing the front of a vehicle with a night vision device.
2B is a view showing a rear camera image displayed by photographing the rear of the vehicle with a rear camera.
3 is a configuration diagram of an external image correction apparatus of the HUD system according to an embodiment of the present invention.
4A is a diagram showing a gamma curve curve in the HUD general mode.
4B is a view showing a gamma curve curve in the HUD general mode and the HUD external image mode together.
FIG. 5 is a diagram showing an example of a unit area of an external image to which the external image correction device of the HUD system of FIG. 3 is applied.
6 is a diagram illustrating correction of an external image by an external image correction device of the HUD system of FIG.
FIG. 7 is a diagram illustrating image correction based on various brightness analysis of an external image by the external image correction apparatus of the HUD system of FIG. 3. FIG.
FIG. 8 is a flowchart of an external image correction method of the HUD system according to an embodiment of the present invention.
9 is a detailed flowchart of an external image correction method of the HUD system of FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

3 is a configuration diagram of an external image correction apparatus of the HUD system according to an embodiment of the present invention. 4A is a view showing a gamma curve curve in the HUD general mode, and FIG. 4B is a view showing a gamma curve curve in the HUD general mode and the HUD external image mode together. 5 is a diagram illustrating an example of a unit area of an external image to which the external image correction device of the HUD system of FIG. 3 is applied.

3, an external image correction apparatus 100 of the HUD system 200 according to an embodiment of the present invention includes an HUD system 200 for creating a virtual image in front of a driver and displaying a head up image, Which is a device for correcting an external image. Specifically, the external image correction apparatus 100 of the HUD system 200 includes an image acquisition unit 110, an image analysis unit 120, a correction determination unit 130, and an image correction unit 140, And may further include an install unit 150.

The image acquiring unit 110 acquires an external image by photographing the outside of the vehicle. The image acquisition unit 110 may be a camera module. Here, at least one of a CCD (Charge Coupled Device) module or a CMOS (Complementary Metal Oxide Semiconductor) module can be used as an image sensor. A series of image processing for the image generated through the camera module is performed in the image obtaining unit 110. [

The result of the image processing may be notified to the driver through a general display device (not shown) installed in the vehicle. Such a display device includes a cathode ray tube (CRT), a liquid crystal display (LCD), a light-emitting diode (LED), an organic light emitting diode (OLED) Organic Light-Emitting Diode) or a plasma display (PDP, Plasma Display Panel), and displays the transferred image information.

The image acquiring unit 110 may acquire an image in front of the vehicle in the driving direction or a rearward image, that is, an external image, and transmit the acquired image to the image analyzing unit 120 or the image dividing unit 150. The image obtaining unit 110 may convert the obtained external image into an image data form and transmit the image data to the image analyzing unit 120 or the image dividing unit 150.

Also, the image acquisition unit 110 may convert the image into a compressed format in which the image is compressed to facilitate data transfer. The image data in the form of a compressed format may have various formats such as MPEG (Moving Picture Experts Group) -1 or MPEG-4.

The camera module constituting the image obtaining unit 110 may be a camera capable of shooting at night so as to detect the precise state of the vehicle at night. That is, it may be a camera module including an infrared sensor module for detecting infrared rays. In particular, the infrared sensor module is preferably a near-infrared sensor module for sensing near-infrared rays, but it is not limited thereto. It is a matter of course that the module may be a far-infrared sensor module for detecting far-infrared rays.

The image analyzing unit 120 analyzes the brightness of an external image acquired and transmitted by the image acquiring unit 110. In particular, the image analyzer 120 may analyze the brightness of the external image by detecting a brightness value of each pixel of the external image in a predetermined section. For example, the pixel value of each pixel in 8 bits can be expressed as 0 to 255, and the brightness of the external image is analyzed based on the pixel value.

Here, if the obtained external image is represented by the RGB method, it is preferable to convert the obtained external image into the YCbCr method to analyze the brightness of the external image. For this purpose, a transformation matrix for converting the RGB method to the YCbCr method may be used. This transformation matrix can be expressed by the following equation (1).

The correction determination unit 130 determines whether the brightness correction of the external image is necessary. More specifically, when the brightness of the external image is lower than a preset reference brightness, the correction determining unit 130 may determine that the brightness correction is necessary. For example, when the average value of the luminance averages of all the pixels of the external image is lower than the reference luminance value, it can be determined that correction is necessary. Alternatively, if the external image is divided into a plurality of regions and the average luminance value difference between the regions is equal to or greater than a reference difference value that is a preset reference, it may be determined that the brightness correction of the external image is necessary. In addition, it will be apparent to those skilled in the art that various algorithms may be used to determine when image brightness correction is needed, and that various algorithms not described herein may be applied.

When the correction determining unit 130 determines that the brightness correction of the external image is necessary, the image correction unit 140 corrects the brightness of the external image. For example, the image correction unit 140 may correct the brightness of the external image by compensating the gamma table. A process of correcting brightness of an image according to compensation of the gamma table will be described with reference to FIGS. 4A and 4B.

As shown in FIG. 4A, the image obtained from the image sensor before being displayed can form an accurate linear curve of input brightness and output brightness. However, as shown in FIG. 4B, the image displayed on the display device has a higher-order function relationship, which is a curve, not a linear relationship. The human eye can not perceive the brightness perfectly linearly and recognizes that the brightness changes in the dark areas have changed more than the actual changes, and that the brightness changes in the bright areas have changed less than the actual changes. In FIG. 4B, the upper curve shows the cognitive sensitivity within a range of brightness (for example, 0 to 255). In other words, the image of the image looks like a curved upward curved image, unlike the actual curve below the slope 1 when viewed by the human eye.

Thus, even though the dark side of the input changes slightly, the output is interpreted as being brighter than the difference. Conversely, if it goes to the bright side, the brightness of the output changes as much as the actual difference. Accordingly, the brightness of the image can be adjusted by changing the value of the left end of the upper curve curve shown in FIG. 4B, thereby brightening the image displayed in black. In other words, when the gamma value is adjusted, the brightness of the black level is more influenced, and the brightness change of the dark portion is more sensitive than the brightness change of the bright portion. Therefore, the image correction unit 140 compensates the gamma table, thereby making it possible to correct the dark external image more brightly.

The image division unit 150 divides the external image acquired by the image acquisition unit 110 into a plurality of unit areas. In analyzing and correcting the brightness of the external image, the entire area of the external image may be sampled and analyzed. However, since the brightness of the external image may be grouped by predetermined areas, a specific area of the external image may be sampled and analyzed. For example, the outside image of a vehicle taken at night may be seen darker than the upper part due to the light illuminated by the lamp of the vehicle. Thus, it may be advantageous to divide the external image into a plurality of unit areas and analyze the brightness of each area.

The external image may be divided into unit regions of MXN by the image divider 120. [ For example, the number of unit areas in the horizontal and vertical directions may be divided differently, but the number of unit areas in the horizontal and vertical units may be divided equally. Preferably, as shown in FIG. 5, the image divider 150 divides an external image into unit areas of 8 × 8 size. This is because it relates to JPEG (Joint Picture Expert Group), which is a standard for image compression, and MPEG, and is the most optimized segmentation method empirically. In addition, each unit area has a constant pixel size, and each unit area may be divided by the image dividing unit 150 to have a pixel size of 16 × 16. Of course, it is not limited to the pixel size but may be divided into various pixel sizes such as 192X128.

When the external image is divided into a plurality of unit areas by the image dividing unit 120, the image analyzing unit 120 can analyze the brightness of each unit area. Since the brightness of the lower portion of the vehicle is relatively dark due to the influence of the headlight of the vehicle, the brightness difference of the external image can be reduced as a whole by performing brightness correction only on a unit region in which the brightness difference of each unit region is relatively dark. To this end, the image correcting unit 140 can correct the brightness by compensating the gamma table only in a unit area darker than a predetermined reference brightness among the unit areas.

FIG. 6 is a diagram illustrating correction of an external image by the external image correction apparatus of the HUD system of FIG. 3, and FIG. 7 is a flowchart of a correction of the external image by the external image correction apparatus of the HUD system of FIG. FIG.

Referring to FIG. 6, the brightness of the image is analyzed by the image correction apparatus 100 for the captured external image A10. After the brightness correction is performed, the corrected image A20 is displayed on the HUD system (200) and displayed as a HUD image. The brightness of the external image A10 is improved by the brightness correction as a whole, so that the black level area of the black image is reduced, so that the HUD image is not transparent and displayed more darkly.

Referring to FIG. 7, in analyzing the brightness of the image by the image correcting apparatus 100, the external image A10 captured and obtained can use various analysis techniques. The brightness of the center part of each unit area is analyzed by dividing the external image A10 into a plurality of unit areas A11 and the brightness of the four edges of the external image A10 is analyzed A12, The brightness of the whole area can be analyzed (A13) or the brightness of the entire area can be analyzed (A13). After analyzing the brightness of the external image A10 by these various analysis techniques, the corrected image A20 is generated by compensating the gamma table when brightness correction is necessary.

6 and 7, it can be seen that the brightness of the corrected image A20 is improved by correcting the brightness by compensating the gamma table by analyzing the brightness of the external image A10. As the corrected image A20 is input to the HUD system 200, the transparency of the HUD image is lowered so that more accurate information is transmitted to the driver.

FIG. 8 is a flowchart of an external image correction method of the HUD system according to an embodiment of the present invention, and FIG. 9 is a detailed flowchart of an external image correction method of the HUD system of FIG.

Referring to FIG. 8, an external image correction method of the HUD system according to an embodiment of the present invention is a method of correcting an external image of an HUD system that displays a head-up display by creating a virtual image in front of a driver. In other words, when the brightness of the external image is corrected, the image recognized by the human eye is brighter than the difference even if the brightness of the dark side is slightly changed. On the contrary, when the brightness is changed more than the actual difference, So that the brightness of the image can be improved as a whole by compensating the gamma table.

To this end, the external image correction method of the HUD system includes the steps of acquiring an external image by capturing the exterior of the vehicle (S10), analyzing the brightness of the external image (S20), and determining whether correction of the external image is necessary S30). If correction is required, the gamma table is compensated to correct the external image (S40). As a result, the darker the darkness of the external image (night vision image, rear camera image, etc.), the darker the HUD image is displayed on the head-up display device, and the HUD image actually displayed is a virtual image, Can be prevented.

At this time, in order to determine whether correction of the external image is necessary (S30), the external image is binarized to obtain a binarized image (S27). If the pixel represented by black in the binarized image exceeds a predetermined reference number, It can be determined that correction of the image is necessary (S29). Here, all the pixels of the binarization image are represented only in black and white. As a criterion for this, a pixel having a low value based on a predetermined threshold value may be expressed as a black pixel and a pixel having a high value. The predetermined threshold value may be an average of brightness values of all the pixels, or iterative selection, two peak method, or the like. Alternatively, the user can set the threshold directly. By expressing the image as a binary image, it is possible to quickly find an area made of a relatively dark area, and brightness correction can be performed only on a part where the area of the black area is large.

By the external image correction method of the HUD system, it is possible to provide the driver with a more accurate HUD image so that the driver can run safely.

Meanwhile, the external image correction method of the HUD system according to an embodiment of the present invention can be implemented as one module by software and hardware, and the embodiments of the present invention described above can be created as a program that can be executed in a computer, And can be implemented in a general-purpose computer that operates the program using a computer-readable recording medium. The computer-readable recording medium is implemented in the form of a carrier wave such as a ROM, a floppy disk, a magnetic medium such as a hard disk, an optical medium such as a CD or a DVD, and a transmission through the Internet. In addition, the computer-readable recording medium may be distributed to a network-connected computer system so that computer-readable codes may be stored and executed in a distributed manner.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

100: External image correction device of HUD system
110:
120: Image analysis section
130:
140: image correction unit
150:
200: HUD system

Claims (12)

1. An external image correcting device of a HUD system for generating a virtual image in front of a driver and displaying a head up image,
An image acquiring unit for acquiring an external image by photographing the outside of the vehicle;
A video divider dividing the external image into a plurality of unit regions;
An image analyzer for analyzing the brightness of each unit area;
A correction determining unit for determining whether brightness correction of the external image is necessary; And
And an image correction unit for correcting the brightness of the external image by compensating the gamma table,
Wherein the gamma table is compensated only for a unit area darker than a preset reference brightness among the unit areas to brighten the dark unit area. The method according to claim 1,
Wherein the image acquiring unit uses any one of a CCD and a CMOS as an image sensor. 3. The method of claim 2,
Wherein the image acquiring unit includes a near-infrared ray sensor. The method according to claim 1,
Wherein the image analyzing unit analyzes the brightness of the external image by detecting a brightness value of each pixel of the external image in a predetermined section. The method according to claim 1,
Wherein the correction determining unit determines that the brightness correction is necessary when the brightness of the external image is lower than a preset reference brightness. delete delete The method according to claim 1,
Wherein the image dividing unit divides the external image into 8x8 size unit regions. delete delete A method for correcting an external image of a HUD system for generating a virtual image in front of a driver and displaying a head-up display,
Capturing the outside of the vehicle to acquire an external image;
Dividing the external image into a plurality of unit areas;
Analyzing brightness of each of the unit areas;
Determining whether correction of the external image is necessary; And
And correcting the external image by compensating the gamma table when correction is required,
Wherein the step of correcting the external image corrects the dark unit area by compensating the gamma table only in a unit area darker than a preset reference brightness among the unit areas. 12. The method of claim 11,
Wherein the step of determining whether correction of the external image is necessary comprises:
Acquiring a binarized image by binarizing the external image; And
And determining that the correction of the external image is necessary if the pixel represented by black in the binarized image exceeds a preset reference number.

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