CN105163036A - Lens automatic focusing method - Google Patents

Lens automatic focusing method Download PDF

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CN105163036A
CN105163036A CN201510657845.2A CN201510657845A CN105163036A CN 105163036 A CN105163036 A CN 105163036A CN 201510657845 A CN201510657845 A CN 201510657845A CN 105163036 A CN105163036 A CN 105163036A
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matrix
subgraph
image
fse
coefficient
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CN105163036B (en
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章睿
杨瑞瑞
汤加跃
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CHENGDU SANLINGJIA MICROELECTRONIC Co Ltd
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CHENGDU SANLINGJIA MICROELECTRONIC Co Ltd
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Abstract

The invention provides a lens automatic focusing method. The method comprises the following steps that: (1) a focusing motor moves step by step in a movable range thereof, a lens collects a plurality of images every time when the focusing motor moves one step, a definition value of each image is calculated, and a mean value is obtained; and (2) all obtained values are compared and judged so as to obtain a maximum image definition value, the focusing motor is moved to the focusing motor position corresponding to the maximum image definition value, and automatic focusing is completed. According to the invention, automatic focusing is realized through software, a fixed algorithm is adopted for carrying out corresponding processing on information contained in digital images, corresponding controlled variables are obtained, and a stepping motor is driven to drive the lens move back and forth until the clearly focused image is obtained, so that the focusing speed is high, and the precision is high.

Description

A kind of self-focusing method of camera lens
Technical field
The present invention relates to technical field of visual measurement, especially relate to a kind of self-focusing method of camera lens.
Background technology
Automatic focus is from general principle, and automatic focus can be divided into two large classes: a class initiatively focuses on, based on the range finding auto-focusing of camera lens and the range measurement between target that is taken; Another kind of is passive focusing, based on the focus detection auto-focusing of imaging clearly on focusing screen.
Initiatively focus on and mainly contain infrared distance measuring method and supersonic sounding method.Infrared distance measuring ratio juris is, initiatively launches infrared ray as range finding light source by camera, and by the geometrical relationship formed between infrared diode, then calculate focusing from; Ultrasonic ranging method is found range the time of propagating between digital camera and object according to ultrasonic wave.Infrared-type and ultrasonic type auto-focusing are that utilization initiatively launches light wave or sound wave is found range, and are referred to as active auto-focusing.Passive focusing mainly contains contrast method and phase method.Contrast method realizes auto-focusing by the contour edge of detected image, and the contour edge of image is more clear, then its brightness step is larger, and the contrast in other words between edge's scenery and background is larger.Otherwise image out of focus, contour edge is smudgy, and brightness step or contrast decline, and out of focus far away, contrast is lower.Phase method is that the side-play amount by detecting picture realizes auto-focusing.
Summary of the invention
The object of the invention is to: for prior art Problems existing, provide a kind of camera lens self-focusing method, the focus method focusing speed solving existing contrast method is slow, and the problem that focusing accuracy is not high.
Goal of the invention of the present invention is achieved through the following technical solutions:
A kind of self-focusing method of camera lens, it is characterized in that, the method comprises the following steps:
(1) focus motor progressively moves in its moveable scope, often moves and moves a step, then camera lens gathers multiple images, and calculates the definition values of often opening image respectively, then averages;
(2) all mean values obtained are compared judgement, obtain maximum image definition values, focus motor is moved to this focus motor position corresponding to maximum image definition values, complete automatic focus.
As further technical scheme, the calculation procedure of often opening the definition values of image is as follows:
(11) Y-component of image is divided into 9 subgraphs of 3x3;
(12) each subgraph is divided into the block of several 8x8 pixels, each piece builds corresponding 8x8 matrix I with the pixel value of its each pixel, integer transform is done to each matrix I, obtain 8x8 the rear coefficient of conversion, square operation is done to each coefficient, obtains the transformation energy matrix B E corresponding to each piece;
(13) to each subgraph, the coefficient of the correspondence position of the transformation energy matrix B E of some pieces that are divided into adds up, each subgraph obtains final subgraph transformation energy matrix PE (i), PE (i) for 8x8 matrix, i value be 0 ~ 8;
(14) be weighted cumulative to the 8x8 coefficient correspondence position of final subgraph transformation energy matrix PE (i) of 9 subgraphs, obtain full images transformation energy matrix E, E is 8x8 matrix;
(15) the 8x8 coefficient of full images transformation energy matrix E is scanned according to Zig-Zag order, be converted to array SE (x), x is 0 ~ 63, wherein SE (0) is called DC energy, SE (1) ~ SE (63) is called interchange data, by SE (1), SE (2), ~ SE (63) is multiplied by 1 respectively, 2, ~ 63, obtain FSE (1), FSE (2), ~ FSE (63), cumulative FX=FSE (1)+FSE (2)+... + FSE (63), FX is called AC energy, AC energy FX is obtained the definition values of image divided by DC energy FSE (0).
As further technical scheme, 9 subgraphs be divided in step (11), wherein center image is comparatively large, and around subgraph is less.
As further technical scheme, the transformation for mula doing integer transform to each matrix I in step (12) is F=I*T 8x8, wherein F is the 8x8 matrix after conversion, and T is that fixed matrix is as follows:
T 8 x 8 = 8 8 8 8 8 8 8 8 12 10 6 3 - 3 - 6 - 10 - 12 8 4 - 4 - 8 - 8 - 4 4 8 10 - 3 - 12 - 6 6 12 3 - 10 8 - 8 - 8 8 8 - 8 - 8 8 6 - 12 3 10 10 - 3 12 - 6 4 - 8 8 - 4 - 4 8 - 8 4 3 - 6 10 - 12 12 - 10 6 - 3 .
As further technical scheme, in step (14) during weighted accumulation, around the weight coefficient of subgraph is less than the weight coefficient of center subgraph.
As further technical scheme, around the weight coefficient of subgraph equals 0.5 ~ 1 times of the weight coefficient of center subgraph.
Compared with prior art, the present invention can pass through software simulating automatic focus, namely by fixing algorithm, respective handling is carried out to the information that digital picture inherence comprises, obtain corresponding controlled quentity controlled variable, Driving Stepping Motor, drives camera lens to move forward and backward, focuses on clearly image until obtain, not only focusing speed is fast, and precision is high.Because passive method does not need extra distance-measuring equipment, therefore adopt the general small volume of this instrument, easy to carry, use flexibly, can be applicable to digital camera, networking makes a video recording in first-class optical system.
Accompanying drawing explanation
Fig. 1 is nine subgraphs being divided into 3X3;
Fig. 2 is the scanning sequency figure of Zig-Zag;
Fig. 3 is automatic focus implementation framework.
Embodiment
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Embodiment
The invention provides a kind of self-focusing method of camera lens, belong to the passive focusing of contrast method.The method is by subregion computed image definition, then weighted average regional image definition, obtains final image definition, according to image definition, in the scope limiting focus motor, and mobile focus motor search maximum image definition.
The inventive method realize principle as shown in Figure 3, gather image by lens optical system, receive cmos image sensor pass the video data of coming, then through the process of automatic focus adjusting module, obtain view data clearly.Its specific implementation step is as follows:
(1) the video data YUV that cmos image sensor transmits is received;
(2) Y-component of a two field picture is divided into 9 subgraphs of 3x3, each subgraph all can be divided into the block of several 8x8.As Fig. 1, wherein center image ratio is comparatively large, and around image is smaller, and we are with from left to right, and order is from top to bottom nominally P0, P1, P2, P3, P4, P5, P6, P7, P8, wherein maximum centered by P4 subgraph;
(3) each subgraph is divided into the block of MxN 8x8, each 8x8 block builds corresponding 8x8 matrix I with the pixel value of each point, does integer transform to the block of each 8x8, obtains 8x8 the rear coefficient of conversion, does square operation to each coefficient;
Wherein, integer transform formula is F=I*T 8x8, F is the 8x8 matrix after conversion, and I is input as image 8x8 block, and T is that fixed matrix is as follows:
T 8 x 8 = 8 8 8 8 8 8 8 8 12 10 6 3 - 3 - 6 - 10 - 12 8 4 - 4 - 8 - 8 - 4 4 8 10 - 3 - 12 - 6 6 12 3 - 10 8 - 8 - 8 8 8 - 8 - 8 8 6 - 12 3 10 10 - 3 12 - 6 4 - 8 8 - 4 - 4 8 - 8 4 3 - 6 10 - 12 12 - 10 6 - 3
The formula each coefficient being done to square operation is:
BE (x, y)=F (x, y) * F (x, y), x=0 ~ 7, y=0 ~ 7, BE is transformation energy matrix.
(4) to each subgraph, the coefficient of the correspondence position of the transformation energy matrix B E of MxN the 8x8 block be divided into by subgraph adds up, each subgraph obtains final subgraph transformation energy matrix PE (i), and PE (i) is 8x8 matrix, i=0 ~ 8;
(5) be weighted cumulative to the 8x8 coefficient correspondence position of final subgraph transformation energy matrix PE (i) of 9 subgraphs, the weight coefficient of the subgraph (weight coefficient of around subgraph centered by the weight coefficient 0.5 ~ 1 times of subgraph less of the weight coefficient of center subgraph around, the present embodiment gets 0.6 times), obtain full images transformation energy matrix E, E is 8x8 matrix.
(6) by the scanning sequency of the 8x8 coefficient of full images transformation energy matrix E by Zig-Zag, be converted to array SE (x), x is 0 ~ 63, wherein SE (0) is called DC energy, SE (1) ~ SE (63) is called interchange data, by SE (1), SE (2) ~ SE (63) is multiplied by 1 respectively, 2 ~ 63, obtain FSE (1), FSE (2), ~ FSE (63), cumulative FX=FSE (1)+FSE (2)+... + FSE (63), FX is called AC energy.ZigZag scanning sequency as shown in Figure 2.
(7) AC energy FX is obtained image definition Fc divided by DC energy FSE (0).
(8) according to present convergence motor mobile range, (motor has been determined, moving range is also fixed), with image clarity values Fc for criterion, mobile focus motor in focus motor mobile range, motor is capable further, at multiple images of this station acquisition, calculate the definition values of often opening image respectively, then average; Then all definition mean value is compared judgement, obtain the focus motor position of maximum image definition values Fc, finally motor is moved to this position, then complete automatic focus.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, it should be pointed out that all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. the self-focusing method of camera lens, it is characterized in that, the method comprises the following steps:
(1) focus motor progressively moves in its moveable scope, often moves and moves a step, then camera lens gathers multiple images, and calculates the definition values of often opening image respectively, then averages;
(2) all mean values obtained are compared judgement, obtain maximum image definition values, focus motor is moved to this focus motor position corresponding to maximum image definition values, complete automatic focus.
2. the self-focusing method of a kind of camera lens according to claim 1, it is characterized in that, the calculation procedure of often opening the definition values of image is as follows:
(11) Y-component of image is divided into 9 subgraphs of 3x3;
(12) each subgraph is divided into the block of several 8x8 pixels, each piece builds corresponding 8x8 matrix I with the pixel value of its each pixel, integer transform is done to each matrix I, obtain 8x8 the rear coefficient of conversion, square operation is done to each coefficient, obtains the transformation energy matrix B E corresponding to each piece;
(13) to each subgraph, the coefficient of the correspondence position of the transformation energy matrix B E of some pieces that are divided into adds up, each subgraph obtains final subgraph transformation energy matrix PE (i), PE (i) for 8x8 matrix, i value be 0 ~ 8;
(14) be weighted cumulative to the 8x8 coefficient correspondence position of final subgraph transformation energy matrix PE (i) of 9 subgraphs, obtain full images transformation energy matrix E, E is 8x8 matrix;
(15) the 8x8 coefficient of full images transformation energy matrix E is scanned according to Zig-Zag order, be converted to array SE (x), x is 0 ~ 63, wherein SE (0) is called DC energy, SE (1) ~ SE (63) is called interchange data, by SE (1), SE (2), ~ SE (63) is multiplied by 1 respectively, 2, ~ 63, obtain FSE (1), FSE (2), ~ FSE (63), cumulative FX=FSE (1)+FSE (2)+... + FSE (63), FX is called AC energy, AC energy FX is obtained the definition values of image divided by DC energy FSE (0).
3. the self-focusing method of a kind of camera lens according to claim 2, is characterized in that, 9 subgraphs be divided in step (11), and wherein center image is comparatively large, and around subgraph is less.
4. the self-focusing method of a kind of camera lens according to claim 2, is characterized in that, the transformation for mula doing integer transform to each matrix I in step (12) is F=I*T 8x8, wherein F is the 8x8 matrix after conversion, and T is that fixed matrix is as follows:
T 8 x × 8 8 8 8 8 8 8 8 8 12 10 6 3 - 3 - 6 - 10 - 12 8 4 - 4 - 8 - 8 - 4 4 8 10 - 3 - 12 - 6 6 12 3 - 10 8 - 8 - 8 8 8 - 8 - 8 8 6 - 12 3 10 10 - 3 12 - 6 4 - 8 8 - 4 - 4 8 - 8 4 3 - 6 10 - 12 12 - 10 6 - 3 .
5. the self-focusing method of a kind of camera lens according to claim 2, is characterized in that, in step (14) during weighted accumulation, around the weight coefficient of subgraph is less than the weight coefficient of center subgraph.
6. the self-focusing method of a kind of camera lens according to claim 5, is characterized in that, around the weight coefficient of subgraph equals 0.5 ~ 1 times of the weight coefficient of center subgraph.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017054677A1 (en) * 2015-09-30 2017-04-06 努比亚技术有限公司 Mobile terminal photographing system and mobile terminal photographing method
CN107277381A (en) * 2017-08-18 2017-10-20 成都市极米科技有限公司 Camera focusing method and device
CN110411945A (en) * 2019-08-06 2019-11-05 沈阳大学 A kind of Image Acquisition camera for assembly line piece test
CN111654632A (en) * 2020-06-19 2020-09-11 展讯通信（上海）有限公司 Contrast focusing method, apparatus, electronic device and storage medium
CN113938596A (en) * 2020-06-29 2022-01-14 北京字节跳动网络技术有限公司 Method and device for shooting image

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Publication number Priority date Publication date Assignee Title
US20090268172A1 (en) * 2008-04-28 2009-10-29 Hon Hai Precision Industry Co., Ltd. Projector with autofocus device
CN101762232A (en) * 2008-12-23 2010-06-30 鸿富锦精密工业（深圳）有限公司 Multi-surface focusing system and method
CN101782369A (en) * 2009-01-16 2010-07-21 鸿富锦精密工业（深圳）有限公司 Image measurement focusing system and method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090268172A1 (en) * 2008-04-28 2009-10-29 Hon Hai Precision Industry Co., Ltd. Projector with autofocus device
CN101762232A (en) * 2008-12-23 2010-06-30 鸿富锦精密工业（深圳）有限公司 Multi-surface focusing system and method
CN101782369A (en) * 2009-01-16 2010-07-21 鸿富锦精密工业（深圳）有限公司 Image measurement focusing system and method

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017054677A1 (en) * 2015-09-30 2017-04-06 努比亚技术有限公司 Mobile terminal photographing system and mobile terminal photographing method
CN107277381A (en) * 2017-08-18 2017-10-20 成都市极米科技有限公司 Camera focusing method and device
CN110411945A (en) * 2019-08-06 2019-11-05 沈阳大学 A kind of Image Acquisition camera for assembly line piece test
CN111654632A (en) * 2020-06-19 2020-09-11 展讯通信（上海）有限公司 Contrast focusing method, apparatus, electronic device and storage medium
CN111654632B (en) * 2020-06-19 2022-02-08 展讯通信（上海）有限公司 Contrast focusing method, apparatus, electronic device and storage medium
CN113938596A (en) * 2020-06-29 2022-01-14 北京字节跳动网络技术有限公司 Method and device for shooting image

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