CN105763816B - It is a kind of based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel - Google Patents
It is a kind of based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel Download PDFInfo
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- CN105763816B CN105763816B CN201610064940.6A CN201610064940A CN105763816B CN 105763816 B CN105763816 B CN 105763816B CN 201610064940 A CN201610064940 A CN 201610064940A CN 105763816 B CN105763816 B CN 105763816B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/73—Circuitry for compensating brightness variation in the scene by influencing the exposure time
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/743—Bracketing, i.e. taking a series of images with varying exposure conditions
Abstract
The invention discloses a kind of based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel, using the DMD camera being made of DMD, CCD, the first and second lens group and processor；It is each seen as being divided into the m exposure groups for including n exposure element and not overlapping for the DMD coding pattern of DMD exposure mask, and sets the number for respectively exposing element in exposure group；In an exposure cycle T of DMD camera, exposure is encoded pixel-by-pixel to N number of different DMD exposure mask respectively, to exposure time information is embedded into the coding exposure image for preserving DMD camera resolution；Ascending order arrangement is made to the exposure element in each exposure group in coding exposure image and is successively renumberd, combination is completed to improve the n width subframe of n times of temporal resolution.The present invention utilizes the spatial light modulating characters of DMD, breaches the limited inherent limitations of traditional camera bandwidth, realizes and common low frame per second camera is changed into high speed camera to achieve the purpose that high speed, high resolution is imaged.
Description
Technical field
The invention belongs to calculate photography field, it is related to a kind of high speed, high resolution imaging method more particularly to a kind of base
In the coding exposure method pixel-by-pixel of DMD (Digital Micromirror Device, Digital Micromirror Device).
Background technique
High-speed imaging technology plays increasingly important role in industrial or agricultural and national defence.With CCD (Charge-
Coupled Device, charge coupled cell) and CMOS (Complementary Metal Oxide Semiconductor, mutually
Mend metal-oxide semiconductor (MOS)) be representative solid state image sensor, because its volume, weight, dynamic range and cost etc. side
The advantage in face, so that different types of solid state image sensor is gradually taken seriously and sends out in ultrafast photoelectric information fields of measurement
Exhibition.However, traditional CCD or CMOS camera is limited by frame per second, the clear figure of fast moving objects cannot be effectively obtained
Picture, trace it to its cause be traditional camera temporal resolution it is smaller.Currently, improving the temporal resolution of tradition CCD or CMOS camera
Method mainly use multiport playback mode and on the spot store (In situ Storage Image Sensor, ISIS) technology
To increase the bandwidth of camera, to realize the optical imagery to high-speed moving object.
In recent years, it with the appearance of emerging calculation type camera, is asked to solve the high speed imaging of all solid state imaging sensor
Topic provides a kind of new scheme.Calculation type camera combines the advantages of computer and camera, controls inhomogeneity by computer
The spatial light modulator of type is to realize the accurate modulation to incident ray, to obtain more ideal visual pattern.
Summary of the invention
To break through the insufficient inherent limitations of traditional camera bandwidth, the present invention devises a kind of novel calculation type camera ---
DMD camera, and there is the imaging advantage that can neatly modulate to light temporal information and spatial information using the camera, it proposes
One kind encoding exposure method pixel-by-pixel, realizes the high speed, high resolution imaging to moving object.
In order to solve the above-mentioned technical problem, proposed by the present invention a kind of based on the high speed, high resolution for encoding exposure pixel-by-pixel
Imaging method, wherein imaging system used is by Digital Micromirror Device DMD, charge coupled cell CCD, the first lens group, second
The constant DMD camera of the linear space that lens group and processor are constituted；The Digital Micromirror Device DMD forms a DMD plane, institute
It states charge coupled cell CCD and forms a CCD as plane, the DMD plane is with the CCD as plane is parallel；First lens
Group is variable focus lens package, and first lens group is in by institute between the Digital Micromirror Device DMD and charge coupled cell CCD
On the primary optical axis of formation, first lens group to by the face DMD imaging whole projection to CCD as plane, the number
Each of each of micro mirror element DMD micro mirror and charge coupled cell CCD pixel correspond；Second lens
Group is a fixed times image-forming objective lens, to by measured object complete imaging in the DMD plane, so that it is determined that the view of DMD camera
Field range and operating distance；Positional relationship between the Digital Micromirror Device DMD, the second lens group and measured object three meets
Tilting scene image-forming condition, tested object plane are conjugated with DMD plane relative to the second lens group each other；The primary optical axis with it is described
Angle where second lens group between optical axis is 24 °, and above-mentioned Digital Micromirror Device DMD, charge coupled cell CCD, first are thoroughly
Microscope group and processor form an electro-optical feedback system；The imaging method of the imaging system the following steps are included:
Step 1: each DMD coding pattern regards that a DMD exposure mask, each DMD exposure mask are drawn as in the DMD plane
It is divided into the m exposure groups not overlapped, includes n exposure element in each exposure group；Each exposure element is set in same exposure
There is different numbers, and exposure element number having the same in different exposure groups of same position in light group；
Step 2: in an exposure cycle T of DMD camera, by control Digital Micromirror Device DMD micro mirror it is inclined
Turn, realized respectively to the exposure element in N number of different DMD exposure mask with identical number while exposing, and the exposure of different numbers
Photoelement successively exposes, to realize coding exposure pixel-by-pixel, coding exposure modulation function is expressed as follows pixel-by-pixel:
In formula (6), Mi(x, y, t) indicates DMD exposure mask function, and the DMD mask exposure time is tims；
Exposure time information is embedded into a coding after Digital Micromirror Device DMD encodes exposure pixel-by-pixel by incident ray
In exposure image, the coding exposure image preserves the resolution ratio of DMD camera, the light intensity function V ' of the coding exposure image
(x, y) is expressed as follows:
In formula (7), the object plane and CCD that (s, t) and (x, y) respectively indicates measured object are as 2-d spatial coordinate in plane；f
The image of (s, t) expression measured object；h(x,y；S, t) indicate the optical transfer function of the DMD camera；
Step 3: in coding exposure image, according to each pixel grey scale distribution characteristics in above-mentioned m exposure group, to it
The exposure element in exposure group after coding exposure makees ascending order arrangement, and successively puts on 1,2,3 to exposure element is arranged ... ...,
N-1, n；By sequencing numbers in above-mentioned all exposure groups be 1 combination of pixels at subframe 1, be by sequencing numbers in all exposure groups
2 combination of pixels at subframe 2, and so on, until subframe n is completed in combination, obtain n width for improving n times of temporal resolution
Frame.
Further, in step 2: to realize N number of different DMD exposure mask in a DMD camera exposure cycle T successively
Exposure is completed, then the time for exposure t of DMD camera exposure cycle T and single DMD exposure maskiThere is following relationship:
T=ti·N+Δt (8)
In formula (8), Δ t indicates charge coupled cell CCD frame read access time.
Compared with prior art, the beneficial effects of the present invention are:
Traditional CCD or CMOS camera temporal resolution is small, cannot effectively detect fast-changing physical phenomenon, improves
Its temporal resolution need to generally change the internal die circuitry structure of original camera, thus design and manufacture complex process, cost
It is high.Under conditions of not changing original camera build-in attribute, the present invention devises a kind of novel DMD camera, utilizes the sky of DMD
Between optical modulation property, propose and a kind of encode exposure method pixel-by-pixel.Technological break-through traditional camera bandwidth is limited intrinsic
Limitation realizes and common low frame per second camera is changed into high speed camera to achieve the purpose that high speed, high resolution is imaged.Theoretically,
This method can promptly improve the temporal resolution several times of the DMD camera, even hundreds times.Meanwhile designed by the present invention
DMD exposure mask can be by binary coding representation, and this encoding mask can have different shapes, including diamond shape, rectangle,
Square or other irregular geometry shapes.Therefore, compared to other high-speed imaging technologies, the method for the present invention is had features designed to
This low, higher flexibility and stronger adaptability.
Detailed description of the invention
Fig. 1 is the light path principle figure of DMD camera.
Fig. 2 (a), Fig. 2 (b) and Fig. 2 (c) are that DMD is matched and calibration experiments result with CCD；Wherein: Fig. 2 (a) is DMD phase
The candy strip that machine uses；Fig. 2 (b) is not matched；Fig. 2 (c) matching.
Fig. 3 (a), Fig. 3 (b) and Fig. 3 (c) are the working principles for encoding exposure method pixel-by-pixel；Wherein: Fig. 3 (a) is DMD
Exposure mask；Fig. 3 (b) is the exposure sequence of different exposure elements；Fig. 3 (c) is that subframe is extracted.
Fig. 4 is the sampling clock control sequential figure of DMD camera.
Fig. 5 is that subframe extracts flow chart.
Fig. 6 is the algorithm flow chart of three element intermediate value quick sorts.
Fig. 7 is the modulated process of the DMD micro mirror in different exposure groups.
Fig. 8 (a) and Fig. 8 (b) is the coding exposure results pixel-by-pixel for recording candle brightness change；Wherein: Fig. 8 (a) is to compile
Code exposure image I；Fig. 8 (b) is subframe: I1、I2、I3、I4。
Fig. 9 (a) and Fig. 9 (b) is the coding exposure results pixel-by-pixel for recording candle and being blown out moment；Wherein: Fig. 9 (a) is
Encode exposure image I；Fig. 9 (b) is subframe: I1、I2、I3、I4。
Figure 10 (a), Figure 10 (b) and Figure 10 (c) are the coding exposure results pixel-by-pixel for recording liquid mixing minor change；Its
In: Figure 10 (a) is coding exposure image I；Figure 10 (b) is subframe: I1、I2、I3、I4；Figure 10 (c) is the entropy of each image.
Specific embodiment
Technical solution of the present invention is described in further detail in the following with reference to the drawings and specific embodiments, it is described specific
Embodiment is only explained the present invention, is not intended to limit the invention.
The present invention is a kind of based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel, wherein imaging system used
It is the DMD being made of Digital Micromirror Device DMD, charge coupled cell CCD, the first lens group 1, the second lens group 2 and processor
Camera, the Digital Micromirror Device DMD forms a DMD plane to structure as shown in Figure 1:, and the charge coupled cell CCD is formed
One CCD is as plane, and the DMD plane is with the CCD as plane is parallel；First lens group 1 is variable focus lens package, described
One lens group 1 is in by being formed by primary optical axis between the Digital Micromirror Device DMD and charge coupled cell CCD, described
First lens group 1 to by the face DMD imaging whole projection to CCD as plane, it is each in the Digital Micromirror Device DMD
Each of a micro mirror and charge coupled cell CCD pixel correspond；Second lens group 2 is a fixed times of imaging object
Mirror, to by measured object complete imaging in the DMD plane, so that it is determined that the field range and operating distance of DMD camera；Institute
The positional relationship stated between Digital Micromirror Device DMD, the second lens group 2 and measured object three meets tilting scene image-forming condition,
Reference line is converged at, tested object plane is conjugated with DMD plane relative to the second lens group 2 each other；The primary optical axis and described the
Angle between two lens groups, 2 place optical axis is 24 °, above-mentioned Digital Micromirror Device DMD, charge coupled cell CCD, the first lens
Group 1 and processor form an electro-optical feedback system.
In the constant imaging system of the linear space being made of Digital Micromirror Device DMD and charge coupled cell CCD,
CCD is really formed by stacking by multiple object points on the object plane of measured object as a picture point of plane, this mixing superposition
Imaging process can be expressed with mathematic integral.
In formula (1), (s, t) and (x, y) respectively indicates object plane and as 2-d spatial coordinate in plane；F (s, t) indicates quilt
Survey the image of object；G (x, y) indicates camera acquired image, also known as degraded image；h(x,y；S, t) indicate the DMD camera
Optical transfer function (PSF).
Light intensity function I (x, y) can be expressed as the time that transform g (x, y) is conjugated the dot product of transform g* (x, y) with it
Average value:
I (x, y)=<g (x, y) g* (x, y)>(2)
Formula (1) is substituted into formula (2), light intensity function I (x, y) may be expressed as: again
Since the light reflected from body surface can be regarded as incoherent plane wave, formula (3) can further table
It is shown as:
If I (x, y, t) corresponds to the space-time convolution sum camera integration time in M × N neighborhood of pixels；M (x, y, t) is indicated
Modulation function between DMD and CCD；The exposure cycle of T expression camera；(x, y) indicates any point in DMD plane, with
CCD is corresponding as the certain point in plane.Therefore, the actual light intensity function V (x, y) of DMD camera can be indicated are as follows:
In formula (5), M (x, y, t) ∈ [0,1].As M (x, y, t)=0, all DMD micro mirrors are closed, can without light
To enter CCD as planar imaging；As M (x, y, t)=1, all DMD micro mirrors are opened.For traditional camera,
Each of described Digital Micromirror Device DMD each of micro mirror and charge coupled cell CCD pixel are one by one
Corresponding, the present invention completes the matching and calibration of DMD micro mirror Yu CCD pixel using the production principle of Moire fringe.It is walked in detail
It is rapid as follows:
(1) according to the rollover characteristics of Digital Micromirror Device DMD itself, DMD exposure mask is arranged to periodic stripe raster pattern
Case.It is made of on each period direction of the grating fringe pattern 4 micro mirrors, and the first two micro mirror is " ON " (opening) state,
Latter two is " OFF " (closing) state.Fig. 2 (a) is the periodic stripe grating pattern being set to set by DMD exposure mask, is divided into figure
Two parts of travers and longitudinal stripe are respectively used to the matching of adjustment longitudinal space and horizontal space matching experiment.
(2) when CCD carries out image sampling to DMD exposure mask (i.e. above-mentioned periodic stripe grating pattern), equally with 4
Pixel is that a cycle carries out extraction sample.First CCD pixel sampled value in each period is chosen, and replicates this sampled value and arrives
At other three pixels.
(3) when DMD micro mirror and CCD pixel correspond, because the sampled value of each period CCD is identical, camera is acquired
Image in will occur without candy strip；When DMD micro mirror and CCD pixel without corresponding completely, due to adjacent periods
CCD sampled value is different, just will appear the progressive candy strip of gray scale after replicating interpolation, this candy strip is also periodically
, this phenomenon is exactly the phase shift Moire fringe phenomenon in surveying.Fig. 2 (b) is DMD camera initial matching and calibration result,
Occurs light and dark Moire fringe in figure.
In experiment, by adjusting the position in z-axis of enlargement ratio and CCD of the first lens group 1 come realize CCD pixel with
The matching of DMD micro mirror then adjusts CCD in the position of x-axis y-axis and around the rotation of x, y, z axis and realizes that CCD pixel and DMD are micro-
The calibration of mirror, shown in experimental result such as Fig. 2 (c).
Assuming that improving N times of temporal resolution of the DMD camera, then its image-forming step is as follows:
In the DMD plane, each DMD coding pattern regards that a DMD exposure mask, each DMD exposure mask are divided into m as
The exposure group not overlapped includes n exposure element in each exposure group；Each exposure element is set to have in same exposure group
There is a different numbers, and exposure element number having the same in different exposure groups of same position；As shown in Fig. 3 (a).
It is real respectively by the deflection of micro mirror in control Digital Micromirror Device DMD in an exposure cycle T of DMD camera
Now the exposure element in N number of different DMD exposure mask with identical number is exposed simultaneously, and the exposure element of different numbers is successively
Exposure, so that coding exposure pixel-by-pixel is realized, as shown in Fig. 3 (b).
As described above, setting Mi(x, y, t) indicates DMD exposure mask function, time for exposure tims.M ' (x, y, t) is indicated by picture
Element coding exposure modulation function, this encodes exposure modulation function pixel-by-pixel and may be expressed as:
In formula (6), Mi(x, y, t) indicates DMD exposure mask function, and the DMD mask exposure time is tims。
Incident ray is after Digital Micromirror Device DMD encodes exposure pixel-by-pixel, as corresponding to each pixel in DMD camera
Time for exposure it is different, to exposure time information is embedded into a coding exposure image, the coding exposure image preservation
There is the high spatial resolution of DMD camera, in conjunction with the actual light intensity function V (x, y) of DMD camera, the light of the coding exposure image
Majorant V ' (x, y) can be expressed as follows:
It is sequentially completed exposure in a DMD camera exposure cycle T for the N number of different DMD exposure mask of realization, then DMD camera
Exposure cycle T and single DMD exposure mask time for exposure tiThere is following relationship (as shown in Figure 4):
T=ti·N+Δt (8)
In formula (8), Δ t indicates charge coupled cell CCD frame read access time, under normal circumstances, the value very little.By formula (8)
The time for exposure t of each DMD exposure mask can be calculatedi。
Under normal conditions, the pixel value of adjacent pixel is relatively and smooth-out, but since DMD realization is compiled pixel-by-pixel
After code exposure modulation, adjacent pixel values will will appear a biggish difference.Meanwhile different exposure elements is using pixel-by-pixel
Its sequence all having the same in each exposure group before and after code exposure.
Therefore, in coding exposure image, according to each pixel grey scale distribution characteristics in above-mentioned m exposure group, it is compiled
The exposure element in exposure group after code exposure makees ascending order arrangement, and successively puts on 1,2,3 to exposure element is arranged ... ..., n-
1, n；By sequencing numbers in above-mentioned all exposure groups be 1 combination of pixels at subframe 1, be 2 by sequencing numbers in all exposure groups
Combination of pixels at subframe 2, and so on, until subframe n is completed in combination, obtain n width for improving n times of temporal resolution
Frame.As shown in Fig. 3 (c) and shown in Fig. 5.
To realize that making quick ascending order to each exposure element in the exposure group after coding exposure arranges, and uses three in the present invention
Element intermediate value quick sort, process are as shown in Figure 6.
It is assumed that including the ordered series of numbers { d of n non-ordered datai}=(d1,...,dn) indicate, then algorithm steps are as follows:
Step1: from ordered series of numbers { diIn optional three element dj, dk, dm, compare these three elements, and take in-between value diFor
Pivotal element.Then by other all elements and pivotal element diIt compares, is not more than d alliData be placed on left subinterval
Ld=(d1,...,di-1) in, it is all to be less than diData be placed on right subinterval Rd=(di+1,...,dn) in.Pivotal element di's
Position remains unchanged.
Step2: all in subinterval LdAnd RdData distinguish recursive call Step1, then using quick sort realize
Sequence to each element in each subinterval；Until the length of respective interval censored data is less than k, Step2 stops executing at this time；
Step3: remaining left subinterval and right subinterval will execute respectively insertion and sort: all remaining data will
To insert it into suitable position in array compared with data orderly before, until all data insertion sorts are completed.
This algorithm steps is successively executed, the ascending sort to exposure element can be fast implemented, obtains ordered data.In order to
The k value of suitable size is obtained, needs to calculate the average time complexity of new algorithm.
The average time complexity of traditional quicksort can indicate are as follows:
Wherein: To(i-1) and To(n-i) left subinterval L is respectively indicateddWith right subinterval RdAverage time complexity.When
Variable i from 1 go to n when, two identical T will be will appear in formula (9)o(0), To(1) ..., To(n-1), thus formula (9) again
It can indicate are as follows:
Transposition and subtraction process are done to formula (10), can be obtained:
It enablesThen formula (11) can indicate are as follows:
Recurrence method is applied to formula (12), available:
Therefore, the average time complexity of traditional quicksort can indicate again are as follows:
Similarly, when variable i goes to n from k, the average time complexity of quick sort can be indicated are as follows:
The average time complexity that intermediate value compares can indicate are as follows:
T2(n)=n (n > 1) (16)
The average time complexity of insertion can indicate are as follows:
In conclusion the average time complexity of three element intermediate value quick sorts can indicate are as follows:
Defined function f (n, k) indicates the difference of the average time complexity of above two method, namely:
And becauseAbove formula can further indicate that are as follows:
As derived function f ' (n, k)=0, function f (n, k) obtains extreme value.Therefore, it enablesThen formula (20) can indicate
Are as follows:
It solves inequality (21), k >=7 can be obtained.At this point, function f (n, k) obtains maximum value, namely when above two method
When average time complexity disparity, the average time complexity of three element intermediate value quick sorts is minimum.Therefore, Dang Gezi
When interval censored data length is less than 7, then insertion sort is applied in remaining data sorting, the three elements intermediate value is quick at this time
The effect of sort algorithm is best.
Embodiment
Under normal circumstances, different shape or different size of DMD exposure mask (such as 3 × 3,9 × 9,16 × 16 can be used
Etc. other kinds of lattice) with rapidly improve DMD camera temporal resolution several times, even hundreds times.Due to this reality
The limitation for applying DMD physical resolution used in example realizes the camera temporal resolution 4 (n=4) times for improving that frame per second is 25fps,
Finally obtain the low spatial resolution sequence of subframes that temporal resolution is 100fps.
As shown in Figure 1, the spatial resolution of CCD camera used is 768 × 576, single CCD pixel dimension is 8.3 μ ms
8.3 μm, exposure cycle T=40ms (25fps), frame read access time tr=0.2ms；The resolution ratio of DMD used is 684 × 608, single
A DMD micromirror size is 7.6 μm of 7.6 μ m；The paraxial magnifying power for adjusting lens group 1 is 1.12, is adjusted by vertical and horizontal
Pixel precisely one-to-one matching is realized in the relative position of CCD and DMD, shown in matching result such as Fig. 2 (c).
Fig. 7 illustrates the modulated process of each DMD micro mirror in each exposure group.In DMD encoding mask, in each exposure group
Comprising 4 (2 × 2 lattice) a exposure elements, and respectively, number is m1, m2, m3, m4.In 0 to the T/4 period, all is micro-
Mirror is in the open state；Within T/4 to the 2T/4 period, m1It closes, m2, m3, m4It opens；Within 2T/4 to the 3T/4 period, m1, m2It closes
It closes, m3, m4It opens；Within 3T/4 to the T period, m1, m2, m3It closes, m4It opens.DMD encoding mask is every ti=9.8ms exposure one
It is secondary, 4 times are recycled altogether in a camera exposure cycle T.To highlight this experimental phenomena and effect, all experiments are all in darkroom
Middle progress.
The high speed, high resolution imaging to multiple and different moving scenes is realized using the method for the present invention.Have been inserted into time letter
The coding exposure image I of breath has high spatial resolution (768 × 576pixels, 25fps), the subframe I of high speed1、I2、I3、I4
(384 × 288pixels, 100fps) will will record and decompose the motion process of high speed image.
In order to prove DMD camera to the modulation effect of light temporal information, first example indicates the brightness of candle flame
Variation, as shown in Fig. 8 (a) and Fig. 8 (b).Fig. 8 (a) is the coding exposure image I encoded pixel-by-pixel after exposure by DMD camera, figure
8 (b) be the 4 different subframe I extracted from Fig. 8 (a)1、I2、I3、I4, it can be observed how subframe is successively more and more brighter.Cause
This, it shows the growth with the time for exposure, and candle can be more and more brighter.
In some sense, the temporal resolution for improving camera is to slow down the process of script fast motion change.Second
A example has recorded the instantaneous variation phenomenon to puff the candle out, as shown in Fig. 9 (a) and Fig. 9 (b).Fig. 9 (a) is to have recorded candle quilt
Coding the exposure image I, Fig. 9 (b) for blowing out instant of time information are the 4 subframe I extracted from Fig. 9 (a)1、I2、I3、I4.It can
To find out that the brightness of subframe is gradually extinguished, the overall process that so far candle extinguishes completely is showed by several subframes.
What third example recorded is the process of liquid mixing minor change.Figure 10 (a) is muddy coding exposure image
I；Figure 10 (b) is 4 subframe I1、I2、I3、I4, they have recorded the overall process that milk is poured into water respectively.The entropy of image can
To indicate the aggregation characteristic of image grayscale distribution, entropy is bigger, illustrates that the information content for including in image is bigger, image is more valuable
Value.The entropy of Figure 10 (c) presentation code exposure image and each subframe.There it can be seen that the 3rd width subframe I3With coding exposure diagram
As the entropy of I is with regard to very close, the 4th width subframe I4The entropy for just having substantially exceeded I illustrates that subframe is gradually achieved than more visible
Visual effect.
Above-mentioned all experimental results show the exposure method of coding pixel-by-pixel proposed by the present invention to all kinds of high-speed motion fields
Scape achieves good visual effect.
Although above in conjunction with figure, invention has been described, and the invention is not limited to above-mentioned specific embodiment parties
Formula, the above mentioned embodiment is only schematical, rather than restrictive, and those skilled in the art are in this hair
Under bright enlightenment, without deviating from the spirit of the invention, many variations can also be made, these belong to guarantor of the invention
Within shield.
Claims (2)
1. a kind of based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel, wherein imaging system used is by number
The linear space that micro mirror element DMD, charge coupled cell CCD, the first lens group (1), the second lens group (2) and processor are constituted
Constant DMD camera；The Digital Micromirror Device DMD forms a DMD plane, and the charge coupled cell CCD forms a CCD picture
Plane, the DMD plane is with the CCD as plane is parallel；First lens group (1) is variable focus lens package, and described first thoroughly
Microscope group (1) is in by being formed by primary optical axis between the Digital Micromirror Device DMD and charge coupled cell CCD, and described the
One lens group (1) to by the face DMD imaging whole projection to CCD as plane, it is each in the Digital Micromirror Device DMD
Each of a micro mirror and charge coupled cell CCD pixel correspond；Second lens group (2) is one fixed times and is imaged
Object lens, to by measured object complete imaging in the DMD plane, so that it is determined that the field range and operating distance of DMD camera；
Positional relationship between the Digital Micromirror Device DMD, the second lens group (2) and measured object three meets tilting scene into slice
Part, tested object plane are conjugated with DMD plane relative to the second lens group (2) each other；The primary optical axis and second lens group
(2) angle where between optical axis is 24 °, above-mentioned Digital Micromirror Device DMD, charge coupled cell CCD, the first lens group (1)
An electro-optical feedback system is formed with processor；It is characterized by:
The imaging method of the imaging system the following steps are included:
Step 1: each DMD coding pattern regards that a DMD exposure mask, each DMD exposure mask are divided into as in the DMD plane
The exposure groups that m is not overlapped include n exposure element in each exposure group；Each exposure element is set in same exposure group
In there is different numbers, and exposure element number having the same in different exposure groups of same position；
Step 2:, by the deflection of micro mirror in control Digital Micromirror Device DMD, dividing in an exposure cycle T of DMD camera
The exposure element in N number of different DMD exposure mask with identical number Shi Xian not exposed simultaneously, and the exposure element of different numbers
It successively exposes, to realize coding exposure pixel-by-pixel, coding exposure modulation function is expressed as follows pixel-by-pixel:
In formula (6), Mi(x, y, t) indicates DMD exposure mask function, and the DMD mask exposure time is tims；
Incident ray is embedded into coding exposure after Digital Micromirror Device DMD encodes exposure pixel-by-pixel, by exposure time information
In image, the coding exposure image preserves the resolution ratio of DMD camera, the light intensity function V ' of the coding exposure image (x,
Y) it is expressed as follows:
In formula (7), the object plane and CCD that (s, t) and (x, y) respectively indicates measured object are as 2-d spatial coordinate in plane；f(s,
T) image of measured object is indicated；h(x,y；S, t) indicate the optical transfer function of the DMD camera；
Step 3:, according to each pixel grey scale distribution characteristics in above-mentioned m exposure group, being encoded to it in coding exposure image
The exposure element in exposure group after exposure makees ascending order arrangement, and successively puts on 1,2,3 to exposure element is arranged ... ..., n-1,
n；By sequencing numbers in above-mentioned all exposure groups be 1 combination of pixels at subframe 1, be 2 by sequencing numbers in all exposure groups
Combination of pixels at subframe 2, and so on, until subframe n is completed in combination, obtain the n width subframe for improving n times of temporal resolution.
2. according to claim 1 based on the high speed, high resolution imaging method for encoding exposure pixel-by-pixel, it is characterised in that:
In step 2: being sequentially completed exposure in a DMD camera exposure cycle T for the N number of different DMD exposure mask of realization, then DMD
The time for exposure t of camera exposure cycle T and single DMD exposure maskiThere is following relationship:
T=ti·N+△t (8)
In formula (8), Δ t indicates charge coupled cell CCD frame read access time.
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