CN105227835A - A kind of assisted focused method and apparatus - Google Patents

Abstract

An auxiliary focusing method, the method is applied to a camera, and the method includes: step A, emit laser light on the target object, and receive the reflected laser light, and calculate the object distance according to the time difference between the emission and reception of the laser light, and perform this step n times, n object distances are calculated; step B, according to the above n object distances, issue n corresponding zoom focus follow curves, and perform corresponding image definition tests; select the one with the highest image definition evaluation value The corresponding object distance is taken as the optimal object distance; step C, delivering the zoom-focus following curve corresponding to the optimal object distance, and performing automatic focusing according to the zoom-focus following curve. The auxiliary focusing method of the present invention utilizes laser precise distance measurement, and can quickly issue a more accurate zooming focus tracking curve, making focusing faster and clearer.

Description

An auxiliary focusing method and device

technical field

The present invention relates to a focusing method and device, in particular to an auxiliary focusing method and device.

Background technique

The high-definition integrated camera will perform a zoom operation during the zooming process. In order to keep the focal plane coplanar with the photosensitive element, the focusing lens must be moved in real time following the movement of the zoom lens. For this purpose, the focus lens can be moved according to the zoom following curve. The zoom follow curve represents the mapping relationship between the zoom position (that is, the position of the zoom motor that controls the movement of the zoom lens) and the focus position (that is, the position of the focus motor that controls the movement of the focus lens) at a certain object distance. Different object distances correspond to different zoom follow curves. At present, most of the automatic focusing methods of cameras use software to estimate the object distance and then issue the zoom follow curve. On the one hand, this processing method has a certain error between the estimated value and the actual object distance, and the issued zoom focus tracking curve is not necessarily correct, so that the image may not be able to focus on the clearest position; on the other hand, during the focusing process In the software estimation, the image sharpness is judged by the FV value (FocusValue, image sharpness description value); in the case of delay in the system, the FV value may be delayed and the position of the clear point may be inaccurate. More zoom follower curves to estimate the object distance to determine the position of the clear point multiple times, and this will cause the focusing action to take longer to complete.

Contents of the invention

In view of the above requirements, the present invention proposes an auxiliary focusing method and device capable of accurate and fast focusing.

The present invention adopts the following technical solutions: an auxiliary focusing method, which is applied to a video camera, and the method includes:

Step A, emit laser light on the target object, and receive the reflected laser light, and calculate the object distance according to the time difference between the emission and reception of the laser light;

Step B. Issue the zoom-focus tracking curve corresponding to the object distance, and perform automatic focusing according to the zoom-zoom focus tracking curve.

The present invention can also adopt the following technical solutions: an auxiliary focusing method, which is applied to a video camera, and the method includes:

Step A, emit n lasers to the target object, and receive n reflected lasers correspondingly, and calculate n object distances according to the emission time of each laser and the time difference of reception; step B, according to the above n object distances, Issue n corresponding zoom focus follow curves, and perform corresponding image clarity tests; select the object distance corresponding to the highest image clarity evaluation value as the optimal object distance;

Step C. Delivering the variable magnification focus following curve corresponding to the optimal object distance, and performing automatic focusing according to the variable magnification focus follow curve.

Preferably, in step B, the image definition test is to run the zoom motor of the camera at a certain fixed position, and then run the focus motor of the camera to the corresponding focus position according to each zoom focus following curve; For the images taken at each focus position, the sharpness evaluation value is calculated to determine the optimal object distance.

Preferably, the certain fixed position to which the variable magnification motor of the camera operates is the telephoto end position.

Preferably, in the step A, the laser is emitted by the laser generator, and a part of the laser passes through the optical system and the amplification and shaping circuit to trigger the counter to start timing; the laser is reflected back after hitting the target, and Received by the laser receiver, a part of the received laser light passes through the optical system and the amplification and shaping circuit to trigger the counter to stop timing, and the object distance can be calculated according to the output of the counter.

The present invention also provides an auxiliary focusing device, which is applied to a video camera, and the device includes:

The laser ranging module is used to emit laser light and receive the laser light reflected by the target object, and calculate the object distance according to the time difference between the emission and reception of the laser light; the variable magnification focusing processing module is used to issue The zoom focus follows the curve for automatic focus.

Preferably, the laser ranging module measures and calculates multiple times and obtains n object distances, and the zoom focus processing module issues corresponding n zoom focus tracking curves, and the cameras test the n zoom focus tracking curves respectively. The image sharpness value, select the primary object distance with the best sharpness as the optimal object distance, and the zoom focus processing module finally issues a zoom focus follow curve corresponding to the optimal object distance.

Preferably, the variable magnification focusing processing module operates the variable magnification motor at the telephoto end position, runs the focus motors to the corresponding focus positions according to the above variable magnification focusing following curve, and takes an image, and calculates its sharpness evaluation value .

Preferably, it also includes a control module, the control module communicates with the laser ranging module through the SPI bus, obtains the object distance information, and transmits it to the variable magnification focusing processing module.

Preferably, the laser ranging module includes a laser generator, an optical system, an amplification and shaping circuit, a laser receiver, and a counter. The laser generator emits laser light, and a part of the laser light passes through the optical system and the amplification and shaping circuit to trigger the The counter starts timing; another part of the laser light is reflected back after hitting the target, and is received by the laser receiver. A part of the received laser light passes through the optical system and the amplification and shaping circuit to trigger the counter to stop timing. According to the output of the counter The object distance can be calculated.

Therefore, the method of the present invention based on the method of measuring the distance of the object based on laser ranging can issue a more accurate zoom follow curve, making the focus faster and clearer.

Description of drawings

The accompanying drawings are for providing a further understanding of the present invention, they are included and constitute a part of the application, the accompanying drawings show the embodiments of the present invention, and together with the description, serve to explain the principle of the present invention. In the attached picture:

FIG. 1 is a schematic diagram of an auxiliary focusing method according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an auxiliary focusing method according to a second embodiment of the present invention.

Fig. 3 is a block diagram of the auxiliary focusing device of the present invention.

detailed description

The invention discloses an auxiliary focusing method, which is applied to a video camera, and the invention also discloses an auxiliary focusing device corresponding to realizing the method. Since other structures of the camera are not the focus of the present invention, this patent will not describe in detail here, but the basic structural design needs to ensure that the laser beam emitted by the ranging module can be in the central area of the camera imaging, so that the object distance tested is exactly the weight of the focus area to ensure the validity of the object distance.

Fig. 1 is a schematic diagram of the auxiliary focusing method in the first embodiment of the present invention. The auxiliary focusing method of the present invention is based on laser ranging, and mainly includes the following steps: n times of laser ranging to obtain n object distance information; from the n object distances Determine the optimal object distance; issue the corresponding zoom focus follow curve according to the optimal object distance for automatic focusing.

In this embodiment, n is 3, that is, the distance measuring step is performed three times, and the optimal object distance is determined from the three object distances. Apparently, those skilled in the art can adjust the value of n as needed.

The process of laser ranging includes: emitting laser light to the target object and receiving the reflected laser light, and calculating the distance between the target object and the camera according to the time difference between the emission and reception of the laser light, that is, the object distance. Specifically, the laser is first emitted by the laser generator, and a part of the laser passes through the optical system and the amplification and shaping circuit to trigger the counter to start timing; the laser is reflected back after hitting the target, and is received by the laser receiver. A part of the received laser light passes through the optical system and the amplification and shaping circuit to trigger the counter to stop counting, and the object distance can be calculated according to the output of the counter.

The way to determine the optimal object distance is as follows: according to the above n object distances, issue n corresponding zoom follower curves for image sharpness test; then select the object distance corresponding to the highest image sharpness evaluation value as optimal object distance. The specific method of the image definition test includes: after running the zoom motor of the camera at a certain fixed position, according to each zoom focus following curve, the focus motor of the camera runs to the corresponding focus position; for each focus position Calculate the sharpness evaluation value of the captured image; finally, the object distance corresponding to the image with the highest sharpness evaluation value is taken as the optimal object distance.

In the above method of testing the image definition evaluation values corresponding to the n variable magnification focus following curves, the certain fixed position to which the zoom motor of the camera operates is the telephoto end position. In other implementation manners, other positions are also possible, and the telephoto end is not necessary.

The automatic focusing step is to move the focus position of the zoom motor and the focus motor of the camera to the calculated specific positions respectively according to the zoom focus tracking curve issued according to the above-mentioned optimal object distance, so as to keep the focus plane and the photosensitive element coplanar , to obtain a better clear image and achieve focus.

Fig. 2 is a schematic diagram of the auxiliary focusing method in the second embodiment of the present invention. The main difference between this method and the auxiliary focusing method in the first embodiment is that the laser ranging step is only performed once to obtain an object distance, and then directly issued The zoom focus corresponding to the object distance follows the curve for automatic focusing. In contrast, the process of determining the optimal object distance is omitted. In view of the accuracy of laser distance measurement in this embodiment, it is considered that the object distance is measured only once, which is also relatively accurate. The specific laser ranging steps are completely the same as the laser ranging method in the first embodiment, and will not be repeated here.

The present invention also provides an auxiliary focusing device corresponding to the above-mentioned auxiliary focusing method, which includes a laser ranging module and a variable magnification focusing processing module, as shown in FIG. 3 .

The laser ranging module is used to emit laser light and receive the laser light reflected by the target object, and measure and calculate the object distance according to the time difference between the emission and reception of the laser light.

In the auxiliary focusing method of the above-mentioned first embodiment, the laser ranging step of the laser ranging module is executed n times to obtain n object distances, and the variable magnification focusing processing module is used to obtain from the laser ranging module The optimal object distance is determined from the calculated n object distances, and a corresponding zoom follow curve is issued according to the optimal object distance, and then automatic focusing is performed. The specific method of determining the optimal object distance has been introduced above, and will not be described in detail.

In the auxiliary focusing method of the second embodiment above, the laser ranging step of the laser ranging module is executed once to obtain an object distance, and the variable magnification focusing processing module issues a corresponding The zoom focus follows the curve for automatic focus.

The auxiliary focusing device of the present invention also includes a control module, the control module mainly realizes the control of the entire camera system, the control module communicates with the laser ranging module through the SPI bus, obtains the object distance information, and The object distance information is transmitted to the variable magnification focusing processing module.

The laser ranging module of the present invention will be described in detail below. The laser ranging module includes a control power supply, a laser generator, a laser receiver, an optical system, an amplification and shaping circuit, a counter, and a sampling circuit. The specific process of the ranging of the laser ranging module is as follows: After receiving the ranging instruction, the laser ranging module enters the ranging working state, and the aforementioned control module sends a reset signal, so that the above-mentioned counter resets the count and realizes the amplification and shaping circuit Gain control, trigger the above-mentioned laser transmitter to emit pulsed laser at this time. A small part of the laser light emitted by the aforementioned laser generator is photoelectrically converted by the sampling circuit, which is used as an opening signal for the distance measurement and counting of the control circuit, and the counter starts counting at this time. Most of the other laser light hits the target and is reflected back and gathered in the laser receiver for photoelectric conversion, and amplified by the amplification and shaping circuit, and then transmitted to the control circuit as the closing signal for distance measurement and counting, and the counter stops counting. According to the output of the counter, The distance to the target to be measured can be calculated. The distance measurement result, that is, the primary object distance information, is calculated and saved to the single-chip microcomputer, and transmitted to the control module.

The auxiliary focusing device of the present invention uses a laser ranging module, which can accurately obtain the object distance, reduces the time for identifying the optimal object distance, and can better reflect the rapid auxiliary focusing ability and Advantages of high-definition imaging.

It will be apparent to those skilled in the art that various modifications and variations can be made to the above-described exemplary embodiments of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention that come within the scope of the appended claims and their equivalents.

Claims (10)

1. an auxiliary focus method, the method is applied to video camera, it is characterized in that, the method comprises: Step A, emit laser light on the target object, and receive the reflected laser light, and calculate the object distance according to the time difference between the emission and reception of the laser light; Step B. Issue the zoom-focus tracking curve corresponding to the object distance, and perform automatic focusing according to the zoom-zoom focus tracking curve. 2. An auxiliary focus method, which is applied to a video camera, is characterized in that the method comprises: Step A, emit n lasers to the target object, and receive n reflected lasers correspondingly, and calculate n object distances according to the time difference between the emission and reception of each of the lasers; Step B. According to the above n object distances, issue n corresponding zoom follower curves, and perform a corresponding image definition test; select the object distance corresponding to the highest image definition evaluation value as the optimal object distance; Step C. Delivering the variable magnification focus following curve corresponding to the optimal object distance, and performing automatic focusing according to the variable magnification focus follow curve. 3. The auxiliary focusing method according to claim 2, wherein in step B, the image definition test is to run the zoom motor of the video camera at a certain fixed position, and follow each variable zoom motor. The focus motor of the camera runs to the corresponding focus position respectively; for the image captured at each focus position, calculate its sharpness evaluation value, and determine the optimal object distance. 4 . The auxiliary focusing method according to claim 3 , wherein the certain fixed position to which the zoom motor of the camera operates is the telephoto end position. 5 . 5. The auxiliary focusing method according to claim 2, wherein in said step A, said laser is emitted by a laser generator, and a part of said laser passes through an optical system and an amplification and shaping circuit to trigger a counter to start Timing: the laser is reflected back after hitting the target and is received by the laser receiver. A part of the received laser passes through the optical system and the amplification and shaping circuit to trigger the counter to stop timing, and it can be calculated according to the output of the counter out of the object distance. 6. An auxiliary focusing device, which is applied to a video camera, is characterized in that the device includes: The laser ranging module is used to emit laser light and receive the laser light reflected by the target object, and calculate the object distance according to the time difference between the emission and reception of the laser light; The variable magnification focus processing module is used to issue a variable magnification focus follow curve according to the object distance for automatic focusing. 7. The auxiliary focusing device according to claim 6, characterized in that: the laser distance measurement module measures and calculates multiple times and obtains n object distances, and the zoom zoom processing module issues corresponding n zoom zoom follow-up curve, the camera respectively tests the image clarity values under the n zoom focus tracking curves, selects the primary object distance with the best clarity as the optimal object distance, and the zoom focus processing module finally issues the corresponding optimal object distance. The zoom focus of the object distance follows the curve. 8. The auxiliary focusing device according to claim 7, wherein the zoom focusing processing module runs the zoom motor at the telephoto end position, and runs the focus motor to the corresponding The focus position of the image is taken, and the sharpness evaluation value is calculated. 9. The auxiliary focusing device according to claim 6, further comprising a control module, the control module communicates with the laser distance measuring module through the SPI bus, obtains the object distance information, and transmits it to the variable magnification Focus processing module. 10. Auxiliary focusing device as claimed in claim 6, characterized in that, the laser ranging module comprises a laser generator, an optical system, an amplification and shaping circuit, a laser receiver and a counter, and the laser generator emits laser light, a part of which The laser beam passes through the optical system and the amplification and shaping circuit to trigger the counter to start timing; another part of the laser light is reflected back after hitting the target, and is received by the laser receiver, and a part of the received laser light passes through the optical system and the amplification and shaping circuit. The circuit triggers the counter to stop timing, and the object distance can be calculated according to the output of the counter.