CN102193164A - Focusing method and camera device - Google Patents

Abstract

The present invention provides a focusing method and a camera device. The focusing method is used for a camera device having a zoom lens, and the method comprises the following steps: (a) detecting a starting position of the zoom lens; (b) capturing image information of the starting position, image information of a first position, and image information of a second position by the zoom lens; (c) determining which image information has the highest contrast value among the image information of the starting position, the image information of the first position, and the image information of the second position; (d) if the contrast value of the image information of the starting position is the highest, finding a correct focusing position according to the starting position by the zoom lens; and (e) if the contrast value of the image information of the first position is the highest, finding the correct focusing position by the zoom lens at a distance away from the camera device relative to the first position and at a non-equidistant focusing distance. The present invention can solve the problem of missing the focusing time due to too long.

Description

Focusing method and camera device

technical field

The invention relates to a focusing method and an imaging device, in particular to a fast and accurate focusing method and an imaging device.

Background technique

In the existing technology, the S0 continuous focusing method of the camera is to calculate the contrast value representing the sharpness at the current position of the lens and the slightly nearer and slightly farther positions. If the contrast value of the middle position is the highest, it is considered that the clearest position is at Within the scanning range, use the mathematical polynomial approximation method to find the clearest position. If it appears at the near or far end, move to the direction where the contrast value is larger until the contrast value decreases. Also use the mathematical polynomial approximation method to find out The clearest position, when the clearest position is found, the contrast value of the clearest position will be recorded to determine whether there is any change in the scene, if there is a change, restart the S0 continuous focusing program, if not, keep converging and do nothing .

However, with the existing technology, no matter whether the spacing is used to use a larger spacing or a smaller spacing, there are disadvantages; a larger spacing will cause instability and shaking and focus accuracy will cause problems; If the spacing is too small, it will lead to slow continuous focusing, especially when the scene moves from far away to very close. Since each sampling point of the lens must consume the time of capturing the frame of the picture, when the lens travel is very long , using smaller spacing will consume a lot of time.

Therefore, it is necessary to provide a focusing method and an imaging device to improve the deficiencies in the prior art.

Contents of the invention

The main purpose of the present invention is to provide a focusing method and an imaging device, so as to achieve the effect of shortening the continuous focusing time of S0.

In order to achieve the above-mentioned purpose, the focusing method of the present invention includes the following steps: detecting the initial position of the zoom lens; capturing the image information of the initial position, the image information of the first position and the image information of the second position by the zoom lens; Wherein the first position is relative to the initial position and away from the camera device, and the second position is relative to the initial position and close to the camera device; determine the image information of the initial position, the image information of the first position and the image information of the second position , which image information has the highest contrast value; if the contrast value of the image information at the initial position is the highest, the zoom lens is used to find the correct focus position according to the initial position; if the contrast value of the image information at the first position is the highest, then Using the zoom lens to move away from the camera device at a non-equidistant focus distance relative to the first position to find the correct focus position; The second position approaches the camera device at non-equidistant focus distance intervals to find out the correct focus position.

The present invention also provides a focusing method for an imaging device with a zoom lens, the method comprising the following steps: (a) detecting a starting position of the zoom lens; (b) capturing the starting position by the zoom lens image information of the initial position, image information of a first position, and image information of a second position; (c) judging the difference between the image information of the initial position, the image information of the first position, and the image information of the second position Among them, which image information has the highest contrast value; (d) if the contrast value of the image information at the starting position is the highest, find a correct focus position based on the starting position through the zoom lens; and (e) if The contrast value of the image information at the first position is the highest, and the correct focus position is found by using the zoom lens to move away from the camera device at a non-equidistant focus distance relative to the first position.

In order to achieve the above object, the imaging device of the present invention includes a zoom lens, an image analysis module, a focus distance providing module, and a processing module; wherein the zoom lens is used to capture image information of multiple locations; the image analysis module is used to analyze multiple locations The contrast value of the image information; the focus distance providing module is used to provide non-equidistant and fixed distance focus distance intervals; the processing module is electrically connected to the zoom lens, the image analysis module and the focus distance providing module; thereby, the processing module controls the zoom lens When performing the focusing action, the zoom lens first captures the image information of multiple positions at non-equidistant focusing distance intervals, and the image analysis module determines that when the contrast value of the image information of each position increases, the image information of the position that first decreases is the approximate focus position; and then find the correct focus position at equidistant focus distance intervals according to the approximate focus position.

The present invention can solve the problem that the focusing time of the zoom lens is too long due to the use of a fixed distance between the focusing distances.

Description of drawings

FIG. 1 is a schematic structural diagram of an embodiment of an imaging device of the present invention.

FIG. 2 is a schematic diagram of an embodiment of the imaging device of the present invention.

FIG. 3 and FIG. 4 are flowcharts of steps related to an embodiment of the focusing method of the present invention.

Description of main component symbols:

Camera device 1 Initial position P0

Zoom lens 10 First position P1

Image analysis module 20 Second position P2

Focusing distance providing module 30 Third position P3

Algorithm module 40 The fourth position P4

processing module 50

Detailed ways

In order to make the above and other objects, features and advantages of the present invention more comprehensible, preferred embodiments are listed below and described in detail in conjunction with the accompanying drawings.

Please refer to FIG. 1 below, which is a schematic structural diagram of an embodiment of the camera device of the present invention.

As shown in FIG. 1 , the imaging device 1 of the present invention includes a zoom lens 10 , an image analysis module 20 , a focus distance providing module 30 , an algorithm module 40 and a processing module 50 ; wherein the zoom lens 10 is used to capture image information of multiple locations. The image analysis module 20 is used to analyze the contrast value of the image information of multiple positions; the focus distance providing module 30 is used to provide non-equidistant and fixed distance focus distance intervals; the processing module 50 is electrically connected to the zoom lens 10 and the image analysis module 20. The focus distance providing module 30 and the algorithm module 40, and the processing module 50 are used to control the work of the above-mentioned devices or modules.

As shown in Figure 2, in one embodiment of the present invention, the imaging device 1 of the present invention is a digital camera, but the present invention is not limited thereto, for example, the imaging device 1 can also be a digital video camera, a camera phone or A personal digital assistant (PDA) with a camera function or other portable electronic devices with a camera function, etc.

Hereinafter, taking the imaging device 1 of the present invention shown in Fig. 1 and Fig. 2 as an example, each step of the focusing method of the present invention will be described in detail. It is not limited to be applied to the imaging device 1 shown in FIG. 1 and FIG. 2 . It should be noted that, in an embodiment of the present invention, the imaging device 1 uses the S0 continuous focusing mode to perform the focusing operation, but the present invention is not limited to the continuous focusing mode.

Please refer to FIG. 1 to FIG. 4 , regarding an embodiment of the focusing method of the present invention, wherein FIG. 3 and FIG. 4 are flow charts of the steps of an embodiment of the focusing method of the present invention.

As shown in FIG. 3 , the present invention first proceeds to step S701 : judging whether there is a correct focus position and whether the correct focus position has not changed.

In one embodiment of the present invention, the correct focus position refers to the focus position at which the zoom lens 10 can capture the clearest image of a scene. In one embodiment of the present invention, the processing module 50 determines Whether the zoom lens 10 has acquired the correct focus position of the scene.

If there is no correct focus position or the correct focus position changes due to the movement of the camera device 1 or the change of the whole scene, go to step S702: detect the initial position of the zoom lens.

As shown in FIG. 2 , in an embodiment of the present invention, the processing module 50 detects the initial position P0 of the zoom lens 10 , where the initial position P0 refers to the position of the zoom lens 10 before the continuous focus mode is performed.

Then proceed to step S703: capture the image information of the initial location, the image information of the first location, and the image information of the second location.

In an embodiment of the present invention, the image information of the initial position P0, the image information of the first position P1 and the image information of the second position P2 are captured by the zoom lens 10, wherein the first position is relative to the initial position of P1. The position P0 is far away from the position of the camera 1 , and the second position P2 is close to the position of the camera 1 relative to the initial position P0 .

Then proceed to step S704: determine which image information has the highest contrast value among the image information at the initial location, the image information at the first location, and the image information at the second location.

In an embodiment of the present invention, the image analysis module 20 is used to analyze which image information has the highest contrast value among the image information of the initial position P0, the image information of the first position P1 and the image information of the second position P2 . In an embodiment of the present invention, the image analysis module 20 uses a contrast value to represent the sharpness of the image of the scene. The higher the contrast value, the clearer it is, but the present invention is not limited thereto.

As shown in FIG. 4 , if the contrast value of the image information at the starting position P0 is the highest, proceed to step S705 : capture the image information of a plurality of adjacent positions before the position.

In an embodiment of the present invention, if the contrast value of the image information at the initial position P0 is the highest, the initial position P0 is the approximate focus position, and the zoom lens 10 captures images of multiple adjacent positions at the initial position P0. In the image information, the adjacent positions are substantially at a fixed distance, and the fixed distance depends on the manufacturer of the zoom lens 10 , but the present invention is not limited thereto. For example, the fixed distance can also be set by the user.

Finally, proceed to step S706: use an algorithm to calculate the image information of each adjacent position and find out the correct focus position.

In an embodiment of the present invention, the algorithm module 40 is used to provide an algorithm and calculate the correct focus position, wherein the algorithm includes a mathematical polynomial approximation method, and the distance and contrast value of the image information of each adjacent position are substituted into the algorithm to obtain The clearest correct focus position, since the use of algorithms to obtain the clearest correct focus position has been widely used in related technical fields, and is not the focus of the present invention, so its detailed calculation principle will not be repeated here.

As shown in FIG. 3 , in an embodiment of the present invention, if the contrast value of the image information at the first position P1 is the highest, proceed to step S707 : capture the image information at the third position.

As shown in FIG. 2 , in one embodiment of the present invention, if the contrast value of the image information at the first position P1 is the highest, the image information at the third position P3 is captured by the zoom lens 10, wherein the third position P3 is far away from The camera device 1 is separated from the first position P1 by a moving distance.

Then proceed to step S708: determine whether the contrast value of the image information at the third position has decreased.

In an embodiment of the present invention, the image analysis module 20 is used to determine whether the contrast value of the image information at the third position P3 is lower than the contrast value of the image information at the first position P1.

If the contrast value of the image information at the third position P3 decreases, proceed to step S705: capture image information at a plurality of adjacent positions before the position.

In an embodiment of the present invention, if the contrast value of the image information at the third position P3 decreases, it means that the correct in-focus position is located between the third position P3 and the first position P1, and the third position P3 is an approximate in-focus position. Then the zoom lens 10 captures the image information of a plurality of adjacent positions before the third position P3, further speaking, the zoom lens 10 captures the image information of a plurality of adjacent positions between the third position P3 and the first position P1 The image information of the adjacent positions is substantially a fixed distance apart, and the fixed distance depends on the manufacturer of the zoom lens 10, but the present invention is not limited thereto.

In an embodiment of the present invention, if the contrast value of the image information at the third position P3 increases, proceed to step S709: set the first position P1 as the initial position P0, and set the third position P3 as the first position P1 , and change the moving distance.

In an embodiment of the present invention, if the contrast value of the image information at the third position P3 increases, it means that the correct focus position is located farther away from the third position P3, and the processing module 50 sets the first position P1 as the starting point. The initial position P0, the third position P3 is set as the first position P1, and the moving distance between the new third position P3 and the new first position P1 is increased by an equal distance or an equal ratio distance, but the present invention does not limit. In an embodiment of the present invention, after step S709 of the present invention is performed, then step S707 is repeated.

In an embodiment of the present invention, if the contrast value of the image information at the second position P2 is the highest, proceed to step S710: capture the image information at the fourth position.

In an embodiment of the present invention, if the contrast value of the image information at the second position P2 is the highest, the image information at the fourth position P4 is captured by the zoom lens 10, wherein the fourth position P4 is close to the camera device 1 and relatively There is a movement distance between the second position P2.

Then proceed to step S711 : determine whether the contrast value of the image information at the fourth position decreases.

In an embodiment of the present invention, the image analysis module 20 is used to determine whether the contrast value of the image information at the fourth position P4 is lower than the contrast value of the image information at the second position P2.

If the contrast value of the image information at the fourth position P4 decreases, proceed to step S705: capture the image information of a plurality of adjacent positions before the position.

In an embodiment of the present invention, if the contrast value of the image information at the fourth position P4 decreases, it means that the correct in-focus position is located between the fourth position P4 and the second position P2, and the fourth position P4 is an approximate in-focus position. Then the zoom lens 10 captures image information of a plurality of adjacent positions before the fourth position P4, further speaking, the zoom lens 10 captures image information of a plurality of adjacent positions between the fourth position P4 and the second position P2 In the image information, the adjacent positions are substantially at a fixed distance, and the fixed distance depends on the manufacturer of the zoom lens 10 , but the present invention is not limited thereto.

In one embodiment of the present invention, if the contrast value of the image information at the fourth position P4 increases, proceed to step S712: set the second position P2 as the initial position P0, and set the fourth position P4 as the second position P2 , and change the moving distance.

In an embodiment of the present invention, if the contrast value of the image information at the fourth position P4 increases, it means that the correct focus position is located between the fourth position P4 and the camera device 1, and the processing module 50 sets the second position P2 to is the initial position P0, the fourth position P4 is set as the second position P2, and the moving distance between the new fourth position P4 and the new second position P is increased by an equal difference distance or an equal ratio distance, but the present invention does not This is the limit. In an embodiment of the present invention, after step S712 of the present invention is performed, then step S710 is repeated.

With the focusing method and camera device of the present invention, the camera device first captures image information of multiple positions at intervals of non-equidistant focus distances, and obtains a rough focus position, and then uses equidistant focus distance intervals according to the rough focus positions to find the correct focus position; since the non-equidistant focus distance intervals are increased by equal distances or proportional distances, it is possible to quickly find an approximate focus position, and then use equidistant focus distance intervals to find the precise correct focus position, It can solve the problem that the focus time of the zoom lens is too long in the prior art because the focus distance intervals are all fixed intervals.

To sum up, the present invention, regardless of its purpose, means, and efficacy, shows its characteristics that are completely different from the known technology. I urge the examiner to be aware of it and grant a patent as soon as possible to benefit the society. I really appreciate it. However, it should be noted that the above-mentioned embodiments are examples only for the convenience of description, and the scope of rights claimed in the present invention should naturally be determined by the scope of the claims, rather than limited to the above-mentioned embodiments.

Claims (12)

1. A focusing method for a camera with a zoom lens, the method comprising the following steps: (a) detecting a starting position of the zoom lens; (b) capturing the image information of the starting position, the image information of a first position and the image information of a second position by the zoom lens; (c) judging which image information has the highest contrast value among the image information at the initial location, the image information at the first location, and the image information at the second location; (d) If the contrast value of the image information at the starting position is the highest, then find a correct focus position based on the starting position through the zoom lens; and (e) If the contrast value of the image information at the first position is the highest, the correct focus position is found by using the zoom lens to move away from the camera device at a non-equidistant focus distance relative to the first position . 2. The focusing method according to claim 1, wherein in step (b), the first position is far away from the imaging device relative to the initial position, and the second position is close to the imaging device relative to the initial position . 3. focusing method as claimed in claim 1, wherein step (e) also comprises the following steps: (f) If the contrast value of the image information at the first position is the highest, capture image information at a third position through the zoom lens, wherein the third position is far away from the camera device and is far away from the first position a moving distance; (g) judging whether the contrast value of the image information at the third position has decreased; (h) If the contrast value of the image information at the third position decreases, then find the correct focus position according to the third position; and (i) If the contrast value of the image information at the third position increases, set the first position as the initial position, set the third position as the first position, and repeat step (f), wherein the The movement distance is increased by one scale distance or one scale distance. 4. The focusing method according to claim 1, wherein after the step (c), further comprising a step (j): if the contrast value of the image information at the second position is the highest, using the zoom lens with respect to the second position Two positions are approached to the camera device at the non-equidistant focus distance interval to find the correct focus position. 5. focusing method as claimed in claim 4, wherein step (j) also comprises the following steps: (k) If the contrast value of the image information at the second position is the highest, capture image information at a fourth position by the zoom lens, wherein the fourth position is close to the camera device and is far away from the second position the distance traveled; (l) judging whether the contrast value of the image information at the fourth position has decreased; (m) If the contrast value of the image information at the fourth position decreases, then find the correct focus position according to the fourth position; and (n) If the contrast value of the image information at the third position increases, set the second position as the initial position, set the fourth position as the second position, and repeat step (k), wherein the The movement distance is increased by the geometric difference distance or the geometric ratio distance. the 6. focusing method as claimed in claim 3, wherein step (h) also comprises the following steps: (o) capturing image information of a plurality of adjacent locations before the third location by the zoom lens, wherein each adjacent location is substantially a fixed distance apart; (p) Using an algorithm to calculate the image information of each adjacent position and find out the correct focus position. 7. focusing method as claimed in claim 5, wherein step (m) also comprises the following steps: (q) capturing image information of the plurality of adjacent locations before the fourth location by the zoom lens, wherein each adjacent location is substantially apart from the fixed distance; and (r) Using the algorithm to calculate the image information of each adjacent position and find out the correct focus position. 8. focusing method as claimed in claim 3, wherein before step (a), also comprise the following steps: (s) determining whether the correct focus position exists and whether the correct focus position has not changed; and (t) If the correct focus position does not exist or the correct focus position changes, go to step (a). 9. The focusing method as claimed in claim 1, wherein the method is used in an S0 continuous focusing mode. 10. A camera device, comprising: a zoom lens for capturing image information of multiple positions; An image analysis module, used to analyze the comparison value of the image information of the multiple locations; A focus distance providing module, used for providing a non-equidistant and a fixed focus distance interval; and A processing module, electrically connected to the zoom lens, the image analysis module and the focus distance providing module; Thereby, the processing module controls the zoom lens to perform a focusing action, the zoom lens first captures image information of multiple positions at intervals of the non-equidistant focusing distance, and the image analysis module judges when the images of each position After the contrast value of the information increases, the image information of the position that first decreases is a rough focus position; then a correct focus position is found at the equidistant focus distance interval according to the rough focus position. 11. The imaging device of claim 10, wherein the imaging device further comprises: An algorithm module, electrically connected to the processing module, the algorithm module is used to provide an algorithm and calculate a correct focus position; Wherein, the zoom lens captures image information of a plurality of adjacent positions before the rough focus position, wherein each adjacent position is substantially apart from the fixed distance, whereby the processing module controls the algorithm module and according to the algorithm and each Image information of adjacent positions and find out the correct focus position. 12. The camera device as claimed in claim 10, wherein the camera device uses an S0 continuous focusing mode. the

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