CN101071251A - Method for estimating automatic focusing least effective sampling points - Google Patents
Method for estimating automatic focusing least effective sampling points Download PDFInfo
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Abstract
The invention relates to an assessment autofocus effective sampling method. The invention of the use of depth of field, the focus test chart in a particular location of the biggest tests of clarity, based on a vague percentage of the value of the test should be the location of a depth of field boundary step, removed only with the greatest depth of field within the scope of the definition of Moves to search the depth of field borders corresponding step the focus of the test plans another test location, definition and calculation of its greatest value, and so on. This will be adopted within the scope of the majority of depth of field sampling neglect from which only a representative sampling point for the steps, but at least effective access to the most effective sampling point, thus reducing auto-focus the search time required.
Description
Technical field
The invention relates to the method for assessment automatic focus effective sampling points, especially about assessing the method for the used sampled point of image extraction element automatic focus.
Background technology
Product such as digital camera, camera cell phone has been the camera installation of popularizing very much, and digital camera must focus on the correct object to obtain good photographic quality, and therefore, self-focusing method logarithmic code camera is very important.
General automatic focus roughly is divided into active automatic focus (Active auto focus) and passive type automatic focus (passive auto focus).Because active automatic focus need additionally be provided with optical transmitting set and receiver, has increased the cost of digital camera, therefore general digital camera all uses passive type automatic focus.
See also Fig. 1, it is the self-focusing process flow diagram of passive type.In the passive type auto focusing method, it (is different lens location or step numbers that camera lens is moved to different focal positions, it is image sampled point (sampling steps), and, decide the clear or fog-level of image according in the definition values (FocusValue) that each lens location obtained.As shown in Figure 1, digital camera is obtained image data (step 101) after camera lens is moved to a position, then calculate the definition values (step 102) of image, judge whether to have obtained maximum definition values (step 103) again, as do not obtain value of maximum articulation, then camera lens is moved on to next lens location and repeat automatic focus program (step 104), then finish the automatic focus program as obtaining value of maximum articulation.
As shown in Figure 1, passive type automatic focus mainly is made up of two parts, and definition values is calculated by first, and second portion is the search of conglomeration.
Have some about self-focusing method for searching, for example: universe search method (GlobalSearch), mountain style search method (Hill-Climbing Search), and two search methods (BinarySearch).Effectively method for searching need be considered and search the needed time, or the correctness of the number of times of camera lens and search.Too many search time can reduce self-focusing efficient, and the number of times that camera lens moves too much can consume the battery electric quantity of camera, but search area then may influence the correctness of search very little.
For example, the universe search method is that the record camera lens whenever moves the image that move a step (or whenever moving a minimum sample unit) obtained, and take out the lens location with utmost sharpness afterwards again, and moving lens is finished automatic focus to the utmost sharpness position.The search one of universe search method is looked for surely to the utmost sharpness image, so the result is the most correct in all methods, but the number of times of needed search time and moving lens is maximum, so elapsed time.For example the speed of two search methods is faster than universe search method again, but the image noise that produces easily causes the peaked judgement of sharpness, and camera lens moves around often, easily produces the collision of mechanical aspects and shortens the camera life-span.Above known method respectively has its relative merits, and the user can select diverse ways to use according to the demand of reality.
Also have fixed-focus position search technique, just set fixing several focal positions, for example: at 30cm, 50cm, 1m, 2m, positions such as 3m, be sampled point, only judge the size of sharpness, so can save the electric weight of search time and camera battery at these sampled points.But the characteristic of each camera lens differs, and the sampled point of fixed position may produce some camera lens can't fine-focused problem.
Summary of the invention
Purpose of the present invention is providing a kind of method of assessing the automatic focus effective sampling points, can effectively determine sampled point and reduce the required search time of automatic focus.
In a preferred embodiment, the invention provides a kind of method of assessing the automatic focus effective sampling points, in order to obtain a plurality of effective sampling points that an image extraction element automatic focus is used, this image extraction element has a camera lens, and this method comprises:
(a). obtain one and focus on test pattern at the value of maximum articulation FVa of some test positions and the camera lens step number Sa of corresponding FVa;
(b). obtain depth of field border step number Sb that should test position according to a fuzzy percent value TH;
(c). search another test position of the pairing focusing test pattern of this depth of field border step number Sb, and calculate the value of maximum articulation FVb of this focusing test pattern in this another location;
(d). according to should fuzzy percent value TH obtaining to another depth of field border step number Sc that should another test position; And
(e). repeating step (c), (d); This Sa wherein, Sb and Sc are this effective sampling points.
In this preferred embodiment, the image extraction element is a digital camera.
Preferably, the camera lens of image extraction element has an effective focal length scope, and this effective focal length scope is from one unlimited long-range to a near-end, and this test position is positioned at this effective focal length scope.
Preferably, the corresponding definition values FV ' of the depth of field border step number Sb of step (b), and FV '/FVa is more than or equal to TH.
Preferably, the corresponding definition values FV of another depth of field border step number Sc of step (d) ", and FV "/FVb is more than or equal to TH.
According to technical scheme of the present invention, can obtain minimum effectively but the most effective sampled point, thereby reduce the required search time of automatic focus.
Description of drawings
Fig. 1 is a passive type automatic focus process flow diagram.
Fig. 2 is the curve map that definition values and camera lens move step number.
Fig. 3 is image extraction element of the present invention and the relative position figure that focuses on test pattern.
Fig. 4 (a)-(c) is the focusing curve figure of the present invention when different object distances.
Wherein, description of reference numerals is as follows:
The D field depth
10 focus on test pattern
20 image extraction elements
30 camera lenses
DI is infinitely long-range
The DN near-end
A, B, C focus on test pattern position FV1-FV6 definition values
S1-S4 camera lens step number
Embodiment
The present invention utilizes the image extraction element, as digital camera, utilizes the characteristic of the depth of field on the optics (depth offield) to assess effective sampling points, to reduce self-focusing search time.
See also Fig. 2, it is that (Focus value FV) moves the curve map of step number with camera lens to known definition values, and wherein transverse axis is that camera lens moves step number, and the longitudinal axis be the definition values of correspondence.As shown in Figure 2, one value of maximum articulation when moving to for the 30th step, camera lens is arranged, but because optical module has the characteristic of the depth of field, that is the image that obtained in field depth D of object can be regarded as clearly, and therefore the definition values that is obtained in the pairing field depth D between the 25th step to the 35th step is all represented acceptable sharp image.That is to say to have 11 step numbers altogether in scope D, according to known universe method for searching, camera lens must be searched the definition values of each step number of these 11 step numbers, just must search 11 times.But because the characteristic of the depth of field, the camera lens step number that belongs in the field depth needn't be searched one by one, is that representational search step number gets final product and only take out a step number that has value of maximum articulation in the field depth.
Please refer to Fig. 3, it is the relative position synoptic diagram of employed focusing test pattern of the inventive method and image extraction element.As shown in Figure 3, the figure shows and focused on test Figure 10, image extraction element 20 and be arranged at camera lens 30 in the image extraction element 20.Wherein image extraction element 20 has an effective focusing range, this effective focusing range, as known to persons skilled in the art, be from the distance between unlimited long-range DI to the near-end DN, in this effective focusing range, move and seek effective sampling points in order to the demand of each step of foundation this method and focus on test Figure 10.
See also Fig. 4 (a), 4 (b), 4 (c), it is the focal length curve map of the inventive method when different object distances, and wherein transverse axis is that camera lens moves step number, and the longitudinal axis is corresponding definition values.Below will describe the operation steps of the inventive method in detail with figure four (a)-(c).
Please refer to Fig. 4 (a), 4 (b), 4 (c), it represents conglomeration respectively at object distance A, B, the focal length curve map of C position.In Fig. 4 (a), will focus on test Figure 10 earlier and be positioned over the A position.The position that focuses on test Figure 10 place can be from the unlimited long-range focal position of image extraction element 20.Then can learn that this focusing test pattern is positioned at a value of maximum articulation FV1 of this A position and the camera lens step number S1 of corresponding FV1 by the universe search.Camera lens 30 is progressively moved forward, and calculate camera lens 30 and whenever move the pairing definition values that moves a step.For example, camera lens 30 moves to camera lens step number S1.1 in regular turn, S1.2, and S1.3, S1.4 and S2, the definition values of wherein corresponding camera lens step number is respectively FV1.1, FV1.2, FV1.3, FV1.4 and FV2.
The inventive method need be calculated a fuzzy percent value TH in advance, and for example 0.94.This fuzzy percent value TH is a numerical value that sets for the depth of field border of seeking each test position.What specify is, each evaluator can decide the size of this numerical value in its sole discretion, and for example according to the image characteristics of image extraction element itself, optical mirror slip characteristic and sharpness function (sharpness function) or the like factor decides the size of TH.
If present camera lens step number (FV1.1, FV1.2, FV1.3, FV1.4 and FV2) ratio (that is FV1.1/FV1, the FV1.2/FV1 of pairing definition values and value of maximum articulation FV1, FV1.3/FV1, FV1.4/FV1 FV2/FV1) greater than TH, represents that then this camera lens step number is to be in the scope of the depth of field, if this ratio, is then represented the field depth that this camera lens step number has broken away from this test position A less than TH.Step number when therefore we obtain this ratio more than or equal to TH is S2 in Fig. 4 (a), as the depth of field border of this test position A.
Please refer to Fig. 4 (b), then move and focus on test Figure 10, and find out the test position of corresponding depth of field border S2 with the universe search method, is position B in Fig. 4 (b).Then repeat the step of Fig. 4 (a), therefore can obtain to test value of maximum articulation FV3 and the depth of field border S3 of Figure 10 B of putting on the throne.Similarly, the ratio FV4/FV3 of pairing definition values FV4 of depth of field border S3 and FV3 is more than or equal to TH.
Please refer to Fig. 4 (c), move to focus on test Figure 10 again, and find out test position corresponding to depth of field border S3 with the universe search method.In Fig. 4 (c), this position is C.Then repeat the step of Fig. 4 (a), therefore the value of maximum articulation FV5 and the depth of field border S4 that can obtain at position C.The ratio FV6/FV5 of pairing definition values FV6 of depth of field border S4 and FV5 is more than or equal to TH.
By that analogy, till focusing test Figure 30 is moved to near-end DN from unlimited long-range DI.After these appraisal procedures finish, can obtain effective sampling points S1, S2, S3, S4 or the like.
After assessing out effective focus point, image extraction element 20 can only be searched at these effective focus points when automatic focus, has therefore saved and has searched the required time.
Be appreciated that by above description, the inventive method is utilized the characteristic of the depth of field, most sampled points in the field depth are ignored, the camera lens step number of sharpness maximum is a sampled point and only get wherein, obtain minimum effectively but the most effective sampled point, not only reduce the required search time of automatic focus, also taken into account the effect of searching.
The above only is preferred embodiment of the present invention, be not in order to limit claim of the present invention, and the technology of the present invention thought can be widely used on other similar test macro, therefore all do not break away from equivalence change or the modification of being finished under the spirit of the present invention, all should be contained in the claim of the present invention.
Claims (5)
1. method of assessing the automatic focus effective sampling points, in order to obtain the used a plurality of effective sampling points of image extraction element automatic focus, this image extraction element has a camera lens, it is characterized in that this method comprises:
(a). obtain one and focus on test pattern at the value of maximum articulation FVa of some test positions and the camera lens step number Sa of corresponding FVa;
(b). obtain depth of field border step number Sb that should test position according to a fuzzy percent value TH;
(c). search another test position of the pairing focusing test pattern of this depth of field border step number Sb, and calculate the value of maximum articulation FVb of this focusing test pattern in this another location;
(d). according to should fuzzy percent value TH obtaining to another depth of field border step number Sc that should another test position; And
(e). repeating step (c), (d); Sa wherein, Sb and Sc are described effective sampling points.
2. the method for assessment automatic focus effective sampling points as claimed in claim 1 is characterized in that this image extraction element is a digital camera.
3. the method for assessment automatic focus effective sampling points as claimed in claim 1, this camera lens that it is characterized in that this image extraction element has an effective focal length scope, this effective focal length scope is from one unlimited long-range to a near-end, and this test position is positioned at this effective focal length scope.
4. the method for assessment automatic focus effective sampling points as claimed in claim 1 it is characterized in that the corresponding definition values FV ' of this depth of field border step number Sb of step (b), and FV '/FVa is more than or equal to TH.
5. the method for assessment automatic focus effective sampling points as claimed in claim 1 is characterized in that the corresponding definition values FV of this another depth of field border step number Sc of step (d) ", and FV "/FVb is more than or equal to TH.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102262332A (en) * | 2010-05-28 | 2011-11-30 | 索尼公司 | Focus control device, focus control method, lens system and focus lens driving method |
| CN101918893B (en) * | 2007-12-27 | 2012-07-18 | 高通股份有限公司 | Method and apparatus with depth map generation |
| CN103209306A (en) * | 2012-01-17 | 2013-07-17 | Lg伊诺特有限公司 | Camera Module, Auto Focus Method And Auto Focus Calibration Method |
| CN103472658A (en) * | 2012-06-06 | 2013-12-25 | 鸿富锦精密工业（深圳）有限公司 | Auto-focusing method |
| CN105824098A (en) * | 2016-05-04 | 2016-08-03 | 广东欧珀移动通信有限公司 | Focusing control method and device, imaging control method and device, and electronic device |
| WO2016161734A1 (en) * | 2015-04-07 | 2016-10-13 | 中兴通讯股份有限公司 | Autofocusing method and device |
| CN106231171A (en) * | 2015-12-31 | 2016-12-14 | 天津天地伟业物联网技术有限公司 | A kind of quick focusing method for video camera |
| CN110753182A (en) * | 2019-09-30 | 2020-02-04 | 华为技术有限公司 | Adjusting method and apparatus of image forming apparatus |
| CN113822877A (en) * | 2021-11-17 | 2021-12-21 | 武汉中导光电设备有限公司 | AOI equipment microscope defect detection picture quality evaluation method and system |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002122776A (en) * | 2000-10-17 | 2002-04-26 | Sharp Corp | Autofocus controller, digital still camera and digital video camera equipped with the same, autofocus control method and recording medium having autofocus control program recorded thereon |
| JP3635327B2 (en) * | 2001-10-01 | 2005-04-06 | 独立行政法人産業技術総合研究所 | High-precision three-dimensional measurement method using focus adjustment mechanism and zoom mechanism and high-precision three-dimensional measurement apparatus therefor |
| CN100357822C (en) * | 2002-05-31 | 2007-12-26 | 金宝电子工业股份有限公司 | Automatic focusing method cooperated with depth of field |
| JP2004077959A (en) * | 2002-08-21 | 2004-03-11 | Nikon Corp | Focus adjusting method and camera |
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2006
- 2006-05-11 CN CN2006100817906A patent/CN101071251B/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101918893B (en) * | 2007-12-27 | 2012-07-18 | 高通股份有限公司 | Method and apparatus with depth map generation |
| CN102262332A (en) * | 2010-05-28 | 2011-11-30 | 索尼公司 | Focus control device, focus control method, lens system and focus lens driving method |
| CN103209306A (en) * | 2012-01-17 | 2013-07-17 | Lg伊诺特有限公司 | Camera Module, Auto Focus Method And Auto Focus Calibration Method |
| CN103472658A (en) * | 2012-06-06 | 2013-12-25 | 鸿富锦精密工业（深圳）有限公司 | Auto-focusing method |
| CN103472658B (en) * | 2012-06-06 | 2017-08-25 | 鸿富锦精密工业（深圳）有限公司 | Atomatic focusing method |
| CN106154688A (en) * | 2015-04-07 | 2016-11-23 | 中兴通讯股份有限公司 | A kind of method and device of auto-focusing |
| WO2016161734A1 (en) * | 2015-04-07 | 2016-10-13 | 中兴通讯股份有限公司 | Autofocusing method and device |
| CN106231171A (en) * | 2015-12-31 | 2016-12-14 | 天津天地伟业物联网技术有限公司 | A kind of quick focusing method for video camera |
| CN106231171B (en) * | 2015-12-31 | 2019-08-20 | 天津天地伟业物联网技术有限公司 | A kind of quick focusing method for video camera |
| CN105824098A (en) * | 2016-05-04 | 2016-08-03 | 广东欧珀移动通信有限公司 | Focusing control method and device, imaging control method and device, and electronic device |
| CN110753182A (en) * | 2019-09-30 | 2020-02-04 | 华为技术有限公司 | Adjusting method and apparatus of image forming apparatus |
| CN110753182B (en) * | 2019-09-30 | 2021-02-09 | 华为技术有限公司 | Adjusting method and apparatus of image forming apparatus |
| CN113822877A (en) * | 2021-11-17 | 2021-12-21 | 武汉中导光电设备有限公司 | AOI equipment microscope defect detection picture quality evaluation method and system |
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