CN101778213B - Automatic focusing method in high-noise environment and digital imaging device thereof - Google Patents

Automatic focusing method in high-noise environment and digital imaging device thereof Download PDF

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CN101778213B
CN101778213B CN2009100015699A CN200910001569A CN101778213B CN 101778213 B CN101778213 B CN 101778213B CN 2009100015699 A CN2009100015699 A CN 2009100015699A CN 200910001569 A CN200910001569 A CN 200910001569A CN 101778213 B CN101778213 B CN 101778213B
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object distance
image
farthest
exposure
nearest
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CN101778213A (en
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廖明俊
彭诗渊
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Altek Corp
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Altek Corp
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Abstract

The invention discloses an automatic focusing method in a high-noise environment and a digital imaging device thereof. The automatic focusing method in the high-noise environment is used for deciding an object distance of the digital imaging device to an object and comprises the following steps of: respectively obtaining two digital images with a first exposure condition and a second exposure condition at a farthest object distance; obtaining two digital images with the first exposure condition and the second exposure condition at a nearest object distance; capturing digital images with the first exposure condition at a plurality of object distances except the farthest object distance and the nearest object distance; selecting at least two images with adjacent object distances and generating a composite image by an image superposition unit; calculating the object distance of the composite image; calculating high-frequency signals in focusing frames of an image with the second farthest object distance, an image with the second nearest object distance and the composite image; and deciding the object distances corresponding to the high-frequency signals of the images from the images and moving an automatic focusing lens to the object distance to complete focusing.

Description

Automatic focusing method and digital image capture device thereof under the high-noise environment
Technical field
The present invention relates to a kind of automatic focusing method and digital image capture device thereof, particularly relate to the digital image capture device that is the automatic focusing method under the high-noise environment and uses its method.
Background technology
Along with the development of digital camera, photography no longer is expensive consumption.The user can be random the desired image of shooting, in order to write down memorable a moment or scene.Generally speaking, be the energy blur-free imaging when taking, all possessed the function of automatic focusing in the most camera.
Existing focusing technology please refer to shown in Fig. 1 a, captures corresponding digitized video in different object distances, and digital camera can obtain object distance and high-frequency signal curve chart shown in Fig. 1 b at get it right high-frequency signal in the burnt frame of each digital eiconometer.Then utilize existing curve to approach (curve fitting) and find the corresponding object distance of high-frequency signal maximum with the evaluation technology, this is optimal focusing object distance.The group of at last camera lens being focused moves to this best focusing position, finishes focusing.
But when low light source environment need use ISO (ISO) condition to take, digitized video went out noise (noise) easily.The denoising ability of existing denoising algorithm is to the digitized video that condition captured of low-light (level) and ISO, and the noise suppression effect of denoising algorithm is quite limited.And the details of scenery makes the automatic Focusing module of digital camera still can't obtain effective high-frequency signal in the high occasion of noise usually also by obfuscation in the digitized video.Under this kind situation, existing focusing technology obtains object distance and the high-frequency signal curve chart shown in Fig. 1 c easily, there is no tangible overall maximum (global maximum) in the drawings and exist, causing the focusing object distance of the decision of focusing program automatically is not the most accurately.
Summary of the invention
In view of above problem, main purpose of the present invention is to provide a kind of automatic focusing method under high-noise environment.
For reaching above-mentioned purpose, the present invention proposes a kind of automatic focusing method under high-noise environment, be applied to the focal length adjustment of a digital image capture device at least one object, it is characterized in that this focusing method automatically comprises the following steps:
This digital image capture device one farthest object distance with one first conditions of exposure take one first farthest the object distance image with take one second object distance image farthest with one second conditions of exposure;
Nearest object distance at this digital image capture device is taken one first nearest object distance image and is taken one second nearest object distance image with this second conditions of exposure with this first conditions of exposure;
Capture corresponding at least one digitized video respectively with this first conditions of exposure during the different object distances between object distance and this nearest object distance farthest at this;
From these digitized videos, choose these digitized videos of at least two adjacent object distances in regular turn, in order to produce a resultant image, repeat this step and all participate in stack in regular turn with the digitized video that first conditions of exposure is captured up to these, produce till these resultant images;
Calculate the corresponding object distance of each this resultant image;
Calculate the high-frequency signal of the partial pixel in these resultant images;
Calculate this second high-frequency signal of at least a portion pixel of object distance image farthest;
Calculate the high-frequency signal of at least a portion pixel of this second nearest object distance image; And
From this farthest the corresponding object distance, this nearest object distance of object distance, these resultant images and its respectively the relation curve of corresponding these high-frequency signals determine the corresponding object distance of high-frequency signal maximum institute obtaining an optimal focusing object distance, and then take this object.
Described automatic focusing method under high-noise environment wherein, also comprises the following steps: in producing these resultant images
The number of these digitized videos of decision stack; And
Select these continuous digitized videos to superpose.
Described automatic focusing method under high-noise environment, wherein, the number of these digitized videos of decision stack is determined by an ambient brightness or noise size.
Described automatic focusing method under high-noise environment, wherein, the calculating of these high-frequency signals utilizes high pass filter, band pass filter, Fu Liye conversion, discrete cosine transform or discrete wavelet conversion to calculate.
The invention provides a kind of digital image capture device that has automatic focusing under high-noise environment, it is used to determine the object distance of this digital image capture device and object.
For reaching above-mentioned purpose, a kind of digital image capture device that under high-noise environment, has automatic focusing proposed by the invention, the object distance that it is used to determine at least one object is characterized in that, this device includes:
One memory cell, in order to store one first object distance image farthest, one second object distance image farthest, one first nearest object distance image, one second nearest object distance image and at least one digitized video, its one farthest object distance with one first conditions of exposure take this first farthest the object distance image with take this second object distance image farthest with one second conditions of exposure, take this first nearest object distance image and take this second nearest object distance image with this first conditions of exposure in a nearest object distance, capture these digitized videos accordingly with this first conditions of exposure during the different object distances outside object distance and this nearest object distance farthest at this with this second conditions of exposure;
One microprocessor is electrically connected at this memory cell, and this microprocessor is in order to load these digitized videos, this first object distance image, this second object distance image, this first nearest object distance image and this second nearest object distance image farthest farthest;
One image superpositing unit, it is arranged in this microprocessor, and this image superpositing unit is in order to from these digitized videos, and at least two these adjacent digitized videos that are chosen at this different object distances in regular turn and captured produce a resultant image;
One object distance computing unit, it is arranged in this microprocessor, and this object distance computing unit is in order to calculate the corresponding object distance of each this resultant image;
One high-frequency signal computing unit, it is arranged in this microprocessor, this high-frequency signal computing unit from these resultant images, this second farthest at least a portion pixel of object distance image and this second nearest object distance image in order to obtain its corresponding high-frequency signal; And
One best focusing position decision unit, it is arranged in this microprocessor, in order to from this farthest the relation curve of corresponding object distance, this nearest object distance these high-frequency signals corresponding of object distance, this resultant image with it determine the corresponding object distance of high-frequency signal maximum institute to obtain an optimal focusing object distance, be used to take this object.
The described digital image capture device that under high-noise environment, has automatic focusing, wherein, also comprise an autofocus lens and an autofocus lens sequential control circuit, this autofocus lens sequential control circuit is electrically connected at this autofocus lens and this microprocessor, this microprocessor is controlled this autofocus lens sequential control circuit, in order to produce at least one index signal that drives this autofocus lens.
The described digital image capture device that under high-noise environment, has automatic focusing, wherein, also comprise a photo-sensitive cell and a photo-sensitive cell sequential control circuit, this photo-sensitive cell sequential control circuit is electrically connected at this photo-sensitive cell and this microprocessor, this microprocessor is controlled this photo-sensitive cell sequential control circuit, drive at least one control signal of this photo-sensitive cell in order to generation, and then make this photo-sensitive cell produce at least one analog signal.
The described digital image capture device that under high-noise environment, has automatic focusing, wherein, also comprise an analog digital conversion processing circuit, it is electrically connected at this photo-sensitive cell, this photo-sensitive cell sequential control circuit and this memory cell, this analog digital conversion processing circuit receives the control of this photo-sensitive cell sequential control circuit and this microprocessor, in order to being a digital signal, and this digital signal is stored to this memory cell with this analog signal conversion.
The described digital image capture device that under high-noise environment, has automatic focusing, wherein, also comprise automatic exposure parameter decision and control unit, it is arranged in this microprocessor, environment when the decision of this automatic exposure parameter is taken according to this digital image capture device with control unit, the time for exposure when determining that this object is taken, aperture size, with one of them person at least of ISO value.
The described digital image capture device that has automatic focusing under high-noise environment, wherein, this high-frequency signal computing unit is high pass filter, band pass filter, Fu Li leaf conversion equipment, discrete cosine conversion device or discrete wavelet conversion equipment.
Describe the present invention below in conjunction with the drawings and specific embodiments, but not as a limitation of the invention.
Description of drawings
Fig. 1 a is that prior art utilizes many images to calculate the schematic diagram of high-frequency signal;
Fig. 1 b is produced high-frequency signal and object distance curve synoptic diagram by prior art;
Fig. 1 c is produced high-frequency signal and object distance curve synoptic diagram by prior art at the strong noise digitized video of low-light (level);
Fig. 2 a utilizes 2 image stacks for the present invention and calculates the schematic diagram of high-frequency signal;
Fig. 2 b is produced high-frequency signal and object distance curve synoptic diagram by the present invention at the strong noise digitized video of low-light (level);
Fig. 3 is a configuration diagram of the present invention;
Fig. 4 a carries out the flow chart of embodiment for the present invention;
Fig. 4 b is for taking the thin portion flow chart of digitized video among the present invention.
Wherein, Reference numeral:
201a first is the object distance image farthest
201b second is the object distance image farthest
202~209 first digitized video~the 8th digitized videos
The 210a first nearest object distance image
The 210b second nearest object distance image
201`~209` first resultant image~the 9th resultant image
300 digital image capture devices
310 autofocus lenses
320 autofocus lens sequential control circuits
330 photo-sensitive cells
340 photo-sensitive cell sequential control circuits
350 analog digital conversion processing circuit
360 memory cell
370 microprocessors
Decision of 371 automatic exposure parameters and control unit
372 image superpositing units
373 object distances are reseted the unit
374 high-frequency signal computing units
375 best focusing position decision unit
Embodiment
Below in conjunction with the drawings and specific embodiments technical scheme of the present invention is made further more detailed description.
For clearly demonstrating basic operation workflow of the present invention, please refer to shown in Fig. 2 a, at first object distance farthest with first conditions of exposure take first farthest object distance image 201a with take the second object distance image 201b farthest with second conditions of exposure; An object distance and the external M of a nearest object distance different object distances (M=8 in this hypothesis Fig. 2 a) capture corresponding digital image, many digital images shown in Fig. 2 a (being first digitized video 202, second digitized video 203, the 3rd digitized video 204, the 4th digitized video 205, the 5th digitized video 206, the 6th digitized video 207, the 7th digitized video 208 and the 8th digitized video 209 among Fig. 2 a) with first conditions of exposure farthest respectively.Under first conditions of exposure, take the first nearest object distance image 210a with the minimum object distance of digital image capture device; Take the second nearest object distance image 210b with second conditions of exposure again.Capture 10 (M+2=10) altogether with first conditions of exposure.Each opens digital image P MAll has corresponding M object distance position S MFirst farthest object distance image 201a with second farthest the relative object distance of object distance image 201b be S 1The relative object distance of first digitized video 202 is S 2The relative object distance of second digitized video 203 is S 3The relative object distance of the 3rd digitized video 204 is S 4The relative object distance of the 4th digitized video 205 is S 5The relative object distance of the 5th digitized video 206 is S 6, the relative object distance of the 6th digitized video 207 is S 7The relative object distance of the 7th digitized video 208 is S 8The relative object distance of the 8th digitized video 209 is S 9The first nearest object distance image 210a is S with the relative object distance of the second nearest object distance image 210b 10,, S wherein 1Be object distance farthest, S 10Be nearest object distance.
Then load the digitized video of taking with first conditions of exposure (202~209); Every N continuous is opened (generation (M-N+3) opening and closing that superpose of the digitized video of N<M) become image.Suppose N=2 in Fig. 2 a.Then obtaining altogether after calculating through stack, 9 opening and closing become image (M-N+3=8-2+3=9).
Next, redefine these (M-N+3) opening and closing and become the corresponding object distance of image.The processing method that redefines please refer to the following stated, at this and with Fig. 2 a as an illustration.For first farthest the object distance of object distance image 201a be S 1, first digitized video 202 object distance be S 2With first first resultant image 201 ' that is formed by stacking of object distance image 201a and first digitized video 202 farthest.The object distance of first resultant image 201 ' is S 1', S wherein 1' be S 1With S 2Center of gravity, that is S 1'=(S 1+ S 2)/2.
Select adjacent digitized video in twos in regular turn, and reset the object distance of these two digital images.Wherein resultant image and new object distance relation please refer to shown in the following table 1.
Resultant image 201` 202` 203` 204` 205` 206` 207` 208` 209`
Object distance S 1 S 2 S 3 S 4 S 5 S 6 S 7 S 8 S 9
Table 1. resultant image and object distance relation table
Set a focusing frame, it is in order to select the partial image in the above-mentioned digitized video.Subsequently, calculate first resultant image to the, nine resultant images (201 ', 202 ' ... with 209 ') in the focusing frame high-frequency signal.And calculate second high-frequency signal in the focusing frame of object distance image 201b and the second nearest object distance image 210b farthest.And find out corresponding object distance according to the high-frequency signal of above-mentioned each image.From the high-frequency signal of above-mentioned image, select one group of maximum optimal focusing object distance in the present invention as output.Because second farthest object distance image 201b and the second nearest object distance image 210b do not synthesize with other image, so its corresponding object distance is still object distance S farthest 1With nearest object distance S 10
Because it is many that the noise of resultant image has been lowered, so the source overwhelming majority of high-frequency signal is the details of shot object, rather than high-frequency noise; Therefore the high-frequency signal object distance corresponding with it that just can obtain shown in Fig. 2 b through calculating like this concerns, has tangible overall maximum and exists.Compared to Fig. 1 c of prior art, the present invention can obtain the curved line relation of clearer and more definite focusing position, and increment is apart from the success rate of judging.
Again according to high-frequency signal object distance relation corresponding, determine the corresponding object distance of high-frequency signal maximum at last to obtain an optimal focusing object distance with it; Autofocus lens is moved to optimal focusing object distance, finish focusing.
On reality is implemented, please refer to shown in Figure 3ly, it is a configuration diagram of the present invention.Include in the digital image capture device 300 of the present invention: autofocus lens 310, autofocus lens sequential control circuit 320, photo-sensitive cell 330, photo-sensitive cell sequential control circuit 340, analog digital conversion processing circuit 350, memory cell 360 and microprocessor 370.
Autofocus lens 310 is electrically connected at autofocus lens sequential control circuit 320.Autofocus lens 310 is in order to adjust the object distance between digital image capture device 300 and object.Autofocus lens sequential control circuit 320 is electrically connected at microprocessor 370, and the index signal that reception microprocessor 370 sends drives autofocus lens 310.The mobile autofocus lens 310 of autofocus lens sequential control circuit 320 control, and with the environment that is taken and object image-forming on photo-sensitive cell 330.Photo-sensitive cell 330 is a kind of photo-electric conversion element, and it is in order to the optical signalling of records photographing environment and object, and this optical signalling is converted to the signal of telecommunication.Photo-sensitive cell 330 can for example be a charge coupled device (charge-coupled device is called for short CCD) or a complementary metal oxide layer semiconductor (ComplementaryMetal-Oxide-Semiconductor is called for short CMOS).
Photo-sensitive cell 330 is in order to the record environment being shot of digital image capture device 300 and the brightness of object, and the brightness transition of object is become electric signal.Photo-sensitive cell sequential control circuit 340 is electrically connected between photo-sensitive cell 330 and the microprocessor 370, and accepts the control signal of the control generation driving photo-sensitive cell 330 of microprocessor 370.Analog digital conversion processing circuit 350 is electrically connected at photo-sensitive cell 330, photo-sensitive cell sequencing control 340 and memory cell 360, and the analog signal conversion that photo-sensitive cell 330 is sent in the control of accepting photo-sensitive cell sequential control circuit 340 is digital signal, is sent to memory cell 360 storages.
Memory cell 360 is electrically connected at analog digital conversion processing circuit 350 and microprocessor 370 in order to store many digital images, memory cell 360.Memory cell 360 is carried out data and is read and write in order to accept microprocessor 370 control.Microprocessor 370 can include the decision of automatic exposure parameter and reset unit 373, high-frequency signal computing unit 374 and best focusing position decision unit 375 with control unit 371, image superpositing unit 372, object distance when carrying out.
When reality was carried out, the decision of automatic exposure parameter can determine two groups of suitable exposure parameters according to the environment of taking with control unit 371, i.e. first conditions of exposure and second conditions of exposure.Conditions of exposure comprises time for exposure, aperture size and sensitization value (International Standards Organization is hereinafter to be referred as ISO).Then microprocessor 370 is set the aperture of autofocus lens 310 by autofocus lens sequential control circuit 320, and by photo-sensitive cell sequential control circuit 340 setting time for exposure and ISO values, utilize first conditions of exposure in object distance farthest, object distance and other M different object distance capture corresponding M+2 and open digital image recently, be stored in the memory cell 360.Capture corresponding 2 digital images with second conditions of exposure in object distance and nearest object distance farthest, be stored in the memory cell 360.
Then image superpositing unit 372, the object distance of control setting in it reseted unit 373 to microprocessor 370, high-frequency signal computing unit 374 carries out start with best focusing position decision unit 375.Image superpositing unit 372 is used to produce many opening and closing in order to the pre-photogra that superposes and becomes image.Object distance is reseted unit 373 in order to calculate the homologue distance of each resultant image, obtains the identical a plurality of homologue distances of resultant image quantity.
Object distance is reseted unit 373, and (the homologue distance of 201`~209`) obtains the identical a plurality of homologue distances of resultant image quantity in order to calculate each resultant image.High-frequency signal computing unit 374 is in order to calculate the high-frequency signal of at least a portion pixel in each resultant image, obtain a plurality of high-frequency signals identical with resultant image quantity, high-frequency signal computing unit 374 is high pass filter (High-pass filter), band pass filter (Band-pass filter), Fu Liye conversion (Fourier transform) device, discrete cosine transform (DiscreteCosine Transform) device or discrete wavelet conversion (Discrete Wavelet Transformation) device.
Best focusing position decision unit 375 in order to from the corresponding object distance of object distance, resultant image farthest, recently determine the relation curve of object distance high-frequency signal corresponding with it high-frequency signal maximum institute accordingly object distance be used to take object with as an optimal focusing object distance.
Suppose that at this stack number is that n opens for convenience of description, the exposure parameter of decision object, the time for exposure of image is that t, ISO value are g, first conditions of exposure is (t, g) expression; Second conditions of exposure be (n*t, g/n).Please also refer to shown in Fig. 4 a, it is the flow chart of the actual execution of the present invention.Be described as follows:
Step S410: according to the brightness of environment or number, first conditions of exposure and second conditions of exposure of noise size decision stack digitized video.
Step S420: take digitized video.
Wherein, in step S420, take in the digitized video, also in addition with reference to the step shown in Fig. 4 b;
Step S421: (t g) takes the first object distance image 201a farthest, and it is stored in the memory cell with first conditions of exposure in object distance farthest;
Step S422: (n*t g/n) takes the second object distance image 201b farthest, and it is stored in the memory cell with second conditions of exposure in object distance farthest;
Step S423: (t g) takes digitized video respectively to other object distance outside object distance farthest and object distance recently, and it is stored in the memory cell with first conditions of exposure;
Step S424: judge whether to be last digitized video; If when being not last, then repeating step S241 is to step S243, all captured image up to the object distance of prior decision;
Step S425: (t g) takes the first nearest object distance image 210a, and it is stored in the memory cell with first conditions of exposure in nearest object distance;
Step S426: (n*t g/n) takes the second nearest object distance image 210b, and it is stored in the memory cell with second conditions of exposure in nearest object distance.
In this explanation the acquisition of image by object distance farthest to nearest object distance, also can be when reality is implemented by nearest object distance to object distance farthest.
Step S430: from first conditions of exposure the digitized video that different object distances was captured, choose continuous two digitized videos in regular turn and superpose in the acquisition of adjacent object distance, produce many opening and closing and become image.
Step S440: the object distance of calculating resultant image.
Step S450: calculate second conditions of exposure acquisition second high-frequency signal of object distance image 201b and the second nearest object distance image 210b farthest.
Step S460: the program of focusing automatically basis is the relation curve of corresponding object distance, nearest object distance and the corresponding high-frequency signal of its difference of object distance, resultant image farthest, determines the corresponding object distance of high-frequency signal maximum, to obtain an optimal focusing object distance.
Step S470: autofocus lens is moved on to this focusing object distance position, finish focusing.
For purposes of illustration, is example at this with 8 object distances, and the digitized video that is captured is defined as first digitized video 202, second digitized video 203, the 3rd digitized video 204, the 4th digitized video 205, the 5th digitized video 206, the 6th digitized video 207, the 7th digitized video 208 and the 8th digitized video 209 respectively.
Then, above-mentioned digitized video (202~209) by after the processing of step S430, can be obtained the first resultant image 201`, the second resultant image 202`, the 3rd resultant image 203`, the 4th resultant image 204`, pentahapto becomes image 205`, the six directions to become image 206`, the 7th resultant image 207`, octadentate to become image 208` and the 9th resultant image 209`.And the high-frequency signal of calculating resultant image.
When step S430 and step S450 calculating high-frequency signal,, also can carry out the calculating of high-frequency signal for the partial image zone in the digitized video except carrying out the calculating of high-frequency signal to whole digital image.Wherein, the calculating of high-frequency signal can be but not be defined as high pass filter (High-pass filter), band pass filter (Band-pass filter), Fu Liye conversion (Fourier transform), discrete cosine transform (Discrete Cosine Transform) or discrete wavelet conversion (Discrete Wavelet Transformation) and calculate.
Though the present invention discloses as above with above-mentioned preferred embodiment, right its is not in order to limit the present invention, for example do not limit the order of the digitized video high-frequency signal of the resultant image and second conditions of exposure shooting in the present invention, as long as corresponding object distance is corresponding correct.In other words can calculate the digitized video that second conditions of exposure is taken earlier, calculate resultant image again.Also can calculate the high-frequency signal of the digitized video of taking in object distance farthest with second conditions of exposure earlier, calculate the high-frequency signal of resultant image again.Last calculating again with the high-frequency signal of second conditions of exposure at the digitized video of object distance shooting recently.
Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (10)

1. the automatic focusing method under high-noise environment is applied to the focal length adjustment of a digital image capture device at least one object, it is characterized in that this focusing method automatically comprises the following steps:
This digital image capture device one farthest object distance with one first conditions of exposure take one first farthest the object distance image with take one second object distance image farthest with one second conditions of exposure;
Nearest object distance at this digital image capture device is taken one first nearest object distance image and is taken one second nearest object distance image with this second conditions of exposure with this first conditions of exposure;
Capture corresponding at least one digitized video respectively with this first conditions of exposure during the different object distances between object distance and this nearest object distance farthest at this;
From these digitized videos, choose these digitized videos of at least two adjacent object distances in regular turn, in order to produce a resultant image, repeat this step and all participate in stack in regular turn with the digitized video that first conditions of exposure is captured up to these, produce till these resultant images;
Calculate the corresponding object distance of each this resultant image;
Calculate the high-frequency signal of the partial pixel in these resultant images;
Calculate this second high-frequency signal of at least a portion pixel of object distance image farthest;
Calculate the high-frequency signal of at least a portion pixel of this second nearest object distance image; And
From this farthest the corresponding object distance, this nearest object distance of object distance, these resultant images and its respectively the relation curve of corresponding these high-frequency signals determine the corresponding object distance of high-frequency signal maximum institute obtaining an optimal focusing object distance, and then take this object.
2. the automatic focusing method under high-noise environment according to claim 1 is characterized in that, also comprises the following steps: in producing these resultant images
The number of these digitized videos of decision stack; And
Select these continuous digitized videos to superpose.
3. the automatic focusing method under high-noise environment according to claim 2 is characterized in that, the number of these digitized videos of decision stack is determined by an ambient brightness or noise size.
4. the automatic focusing method under high-noise environment according to claim 1 is characterized in that, the calculating of these high-frequency signals utilizes high pass filter, band pass filter, Fu Liye conversion, discrete cosine transform or discrete wavelet conversion to calculate.
5. digital image capture device that under high-noise environment, has automatic focusing, the object distance that it is used to determine at least one object is characterized in that, this device includes:
One memory cell, in order to store one first object distance image farthest, one second object distance image farthest, one first nearest object distance image, one second nearest object distance image and at least one digitized video, its one farthest object distance with one first conditions of exposure take this first farthest the object distance image with take this second object distance image farthest with one second conditions of exposure, take this first nearest object distance image and take this second nearest object distance image with this first conditions of exposure in a nearest object distance, capture these digitized videos accordingly with this first conditions of exposure during the different object distances outside object distance and this nearest object distance farthest at this with this second conditions of exposure;
One microprocessor is electrically connected at this memory cell, and this microprocessor is in order to load these digitized videos, this first object distance image, this second object distance image, this first nearest object distance image and this second nearest object distance image farthest farthest;
One image superpositing unit, it is arranged in this microprocessor, and this image superpositing unit is in order to from these digitized videos, and at least two these adjacent digitized videos that are chosen at this different object distances in regular turn and captured produce a resultant image;
One object distance computing unit, it is arranged in this microprocessor, and this object distance computing unit is in order to calculate the corresponding object distance of each this resultant image;
One high-frequency signal computing unit, it is arranged in this microprocessor, this high-frequency signal computing unit from these resultant images, this second farthest at least a portion pixel of object distance image and this second nearest object distance image in order to obtain its corresponding high-frequency signal; And
One best focusing position decision unit, it is arranged in this microprocessor, in order to from this farthest the relation curve of corresponding object distance, this nearest object distance these high-frequency signals corresponding of object distance, this resultant image with it determine the corresponding object distance of high-frequency signal maximum institute to obtain an optimal focusing object distance, be used to take this object.
6. the digital image capture device that under high-noise environment, has automatic focusing according to claim 5, it is characterized in that, also comprise an autofocus lens and an autofocus lens sequential control circuit, this autofocus lens sequential control circuit is electrically connected at this autofocus lens and this microprocessor, this microprocessor is controlled this autofocus lens sequential control circuit, in order to produce at least one index signal that drives this autofocus lens.
7. the digital image capture device that under high-noise environment, has automatic focusing according to claim 5, it is characterized in that, also comprise a photo-sensitive cell and a photo-sensitive cell sequential control circuit, this photo-sensitive cell sequential control circuit is electrically connected at this photo-sensitive cell and this microprocessor, this microprocessor is controlled this photo-sensitive cell sequential control circuit, drive at least one control signal of this photo-sensitive cell in order to generation, and then make this photo-sensitive cell produce at least one analog signal.
8. the digital image capture device that under high-noise environment, has automatic focusing according to claim 7, it is characterized in that, also comprise an analog digital conversion processing circuit, it is electrically connected at this photo-sensitive cell, this photo-sensitive cell sequential control circuit and this memory cell, this analog digital conversion processing circuit receives the control of this photo-sensitive cell sequential control circuit and this microprocessor, in order to being a digital signal, and this digital signal is stored to this memory cell with this analog signal conversion.
9. the digital image capture device that under high-noise environment, has automatic focusing according to claim 5, it is characterized in that, also comprise automatic exposure parameter decision and control unit, it is arranged in this microprocessor, environment when the decision of this automatic exposure parameter is taken according to this digital image capture device with control unit, the time for exposure when determining that this object is taken, aperture size, with one of them person at least of ISO value.
10. the digital image capture device that under high-noise environment, has automatic focusing according to claim 5, it is characterized in that this high-frequency signal computing unit is high pass filter, band pass filter, Fu Li leaf conversion equipment, discrete cosine conversion device or discrete wavelet conversion equipment.
CN2009100015699A 2009-01-12 2009-01-12 Automatic focusing method in high-noise environment and digital imaging device thereof Expired - Fee Related CN101778213B (en)

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