This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 096146862 filed in Taiwan, R.O.C. on Dec. 7, 2007, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an image processing method. More particularly, the present invention relates to a method of displaying a shot image on a car reverse video system.
2. Related Art
Car has gradually become the major transportation means, and as the rapid progress of the car industry, the mass has increasingly higher requirements on the driving safety and comfortableness. The requirements, especially for the driving safety, for example, safety belt, safety air bag, lane departure warning (LDW) system, reverse radar, and other patents for car have been proposed one after another, so as to ensure the driving safety. Generally, rear view mirrors are disposed on the left and right sides of the car and in front of the driver's seat, and provided for the driver to view the circumstance behind the car, thereby reducing the possibility of being crashed externally. In addition, in some cars, a rear ground mirror is further disposed at the back of the car (for example, above a spoiler), which is provided for the driver to directly view the situation within one meter from the ground at the rear end of the car. However, practically, because of the visual field problem of the reflecting mirrors and the rear view mirrors, the visual field information still includes visual field dead angle/blind spot region. Therefore, the car reverse radar technique has been increasingly developed to solve the problem of the visual field dead angle/blind spot region, in which a reverse radar system sends out a signal, and once the reverse radar system receives a signal reflected back due to encountering an obstacle, a warning sound is generated. However, the position where the reverse radar is mounted and the angle for sending the signal by the reverse radar may also have the dead angle problem. For example, when the position of the obstacle is lower than a preset critical point, the reverse radar system cannot receive a reflected signal, such that it cannot detect the obstacle. In addition, the reverse radar system only informs the driver with warning sound, but cannot show the real situation behind the car in real time.
In recent years, a car reverse video system used for shooting the scene behind the car when the car is reversed has been developed. Through the car reverse video system, the traffic situation behind the car is shown in real time (for example, which kind of obstacle behind the car can be determined), and the driver may reverse the car while directly watching the real images behind the car. In usage, the car reverse video system also has the dead angle problem, since the shooting angle is not wide enough. Currently, one way of solving the dead angle problem when shooting images by the car reverse video system is to use a movable lens to dynamically calibrate the shooting angle. When the obstacle is relatively far away from the back of the car, the shooting viewing angle is relative horizontal. When the obstacle is relatively close to the back of the car, the shooting viewing angle is adjusted downwards, such that the viewing angle is made to be close to the back of the car, and thus, the driver is made to have a distinct sense of distance. However, the movable shooting lens device has a higher cost and a higher damaging probability than that of the fixed lens.
In view of the above viewing angle problem of the car reverse video system, the present invention is directed to a method of displaying a shot image on a car reverse video system, in which a scene image is deformed by calibrating pixel pitches in the shot scene image, such that the shot scene image generates a visual effect of switching the viewing angle.
In order to achieve the above objective of switching the image viewing angle of the shot image, the present invention includes the following steps. Firstly, a scene image behind a car is shot through a photographic lens. Next, a distance detector is activated to detect a distance from an obstacle behind the car. Then, when the distance from the obstacle is smaller than a preset distance, a scaling ratio is set according to an equation below:
Scaling Ratio=Preset Distance/Distance from Obstacle;
Then, according to the scaling ratio and distances between a reference point and all the pixels in the scene image, the pixel pitches are adjusted, such that the scene image is deformed, so as to achieve an effect of switching the viewing angle.
In the method of displaying the shot image on the car reverse video system according to a preferred embodiment of the present invention, the lens of the car reverse video system may be a common lens, a wide angle lens, or a fisheye lens.
In the method of displaying the shot image on the car reverse video system according to the preferred embodiment of the present invention, the step of calculating the distance from the obstacle includes: activating the distance detector and sending an ultrasonic signal; and receiving the ultrasonic signal; and meanwhile, calculating a distance between the obstacle and the car according to a returning time of the ultrasonic signal.
In the method of displaying the shot image on the car reverse video system according to the preferred embodiment of the present invention, the motion of adjusting the pixel pitches in the scene image includes the following steps. Firstly, a first scaling region is disposed at an upper half position of the scene image, and a second scaling region is disposed at a lower half position of the scene image. Then, according to the above scaling ratio, the pixel pitches in the first scaling region are reduced by equal proportion, and the pixel pitches in the second scaling region are enlarged by equal proportion.
In the method of displaying the shot image on the car reverse video system according to the preferred embodiment of the present invention, the motion of adjusting the pixel pitches of the scene image further includes the following steps. Firstly, a reference line is disposed at the scene image according to the scaling ratio. Next, all those pixels above the reference line in the scene image are filtered out. Then, the remaining pixel pitches are increased in a manner of logarithmic scale according to the distance from the reference line. Then, a calibrated image is generated according to the calibrated pixel pitches, and then the calibrated image is displayed on a screen of the car reverse video system.
In view of the above, in the method of displaying the shot image on the car reverse video system of the present invention, the scaling ratio of the shot scene image is mainly determined by means of detecting the distance between the car and the obstacle, and then the pixel pitches in the scene image are calibrated according to the scaling ratio, thus the pixel pitches of the scene image close to the ground are enlarged, thereby generating a visual effect that “the shooting angle is adjusted downwards”, so as to achieve an effect of switching the shooting viewing angle, without adjusting the angle of the shooting lens.
The present invention will become more fully understood from the detailed description given herein below for illustration only, which thus is not limitative of the present invention, and wherein:
The objectives and features of the present invention will be described below in detail through preferred embodiments. However, the concepts of the present invention can also be used in other scope. The embodiments listed below are merely intended to illustrate the objectives and implementation of the present invention, but not to limit the scope thereof.
Scaling Ratio=Preset Distance/Distance from Obstacle (Step S130);
Then, according to the scaling ratio and distances between a reference point and all the pixels in the scene image, the pixel pitches are adjusted, such that the scene image is deformed, so as to achieve an effect of switching the viewing angle (Step S140).
The method of displaying the shot image on the car reverse video system in this embodiment is illustrated below through the following example.
Once the car reverse video system determines that the distance from the obstacle 230 behind the car is smaller than the preset distance, it begins to process the scene image. In this embodiment, the preset distance is, for example, the distance d. According to a ratio of the preset distance to the distance from the obstacle (the ratio is 2 in this embodiment), a scaling ratio is calculated, and the pixel pitches in the shot scene image are adjusted according to the scaling ratio, so as to generate the deformed scene image.
In addition, in some embodiments, the effect of overlooking the ground is achieved by cutting off the upper part of the shot scene image and enlarging the lower part of the image.
To sum up, the car reverse video system does not use a photographic lens with variable shooting angle, but merely executes the “method of displaying a shot image on a car reverse video system” of the present invention to process the image shot by the photographic lens with fixed shooting angle, and thus visually changing the viewing angle of the shot scene image. The method of displaying the shot image of the present invention at least has the following advantages.
1. As for the shooting and imaging of the car reverse video system, the viewing angle of the shot image is changed according to the distance from the obstacle, such that the driver has a distinct sense of distance, which is helpful for the driver to grasp the road situation behind the car.
2. The photographic lens can change the shot viewing angle, without being turned frequently, which effectively avoids the probability of damaging the photographic lens, and thereby saving the maintenance cost of the car reverse video system.
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96146862 A | Dec 2007 | TW | national |
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