CN116774496A - Phase shift detection automatic focusing device and method for color double-hole modulation - Google Patents
Phase shift detection automatic focusing device and method for color double-hole modulation Download PDFInfo
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Abstract
The invention discloses a phase shift detection automatic focusing device for color double-hole modulation, which comprises: the device comprises a spectroscope, a first barrel lens, a first color image sensor, a distance increasing lens, a double-hole diaphragm, a red light filter, a green light filter, a second barrel lens and a second color image sensor. The invention also provides a phase shift detection automatic focusing method of color double-hole modulation, which consists of a distance-increasing lens, a double-hole diaphragm, a red light filter, a green light filter, a barrel lens and a color camera, and can convert the axial defocusing displacement of a sample into the transverse pixel offset between red and green channels of the color camera, and the defocusing position of the sample is reversely solved by calculating the pixel offset between the red and green channels through an image registration algorithm by utilizing a relation curve of the pre-calibrated pixel offset and the defocusing displacement, so that the single-frame real-time automatic focusing of a pathological section scanner is realized, the problem that the original technology cannot distinguish positive and negative defocusing directions is solved, and the scanning time is saved.
Description
Technical Field
The invention belongs to the technical field of pathological section scanners, and particularly relates to a phase shift detection automatic focusing device and method for color double-hole modulation.
Background
The pathological section scanner mechanically scans the whole area of the tissue section by using the electric displacement platform and forms a whole digitized section by an image splicing mode, is a hardware foundation of modern digital pathology, and provides important support and help for pathological diagnosis and medical research. The limited depth of field is an inherent problem with conventional optical microscopy imaging systems, which is primarily related to the numerical aperture of the microscope objective. In the case of a high magnification objective, the numerical aperture of the objective is also relatively high, taking for example an objective with a magnification of 20 times and a numerical aperture of 0.75, the depth of field of the system is about 1 micron. The surface height of pathological tissue sections is often uneven, when a traditional optical microscope collects images with different view fields, the depth of field is smaller, so that a microscope system is defocused and the images become fuzzy, and therefore, the clear and high-quality images can be obtained only by repeated fine focusing, and the working efficiency is lower. The pathological section scanner adopts an electric displacement platform to scan the sample and relies on an automatic focusing technology to search the focusing position of the sample. The automatic focusing technology is an important factor affecting the scanning efficiency and focusing precision of the pathological section scanner, and can directly affect the section scanning speed and the definition of the section image.
In the existing automatic focusing technology, an automatic focusing method based on double LED illumination depends on LED illumination samples with different angles, axial defocusing displacement can be converted into transverse image offset, and the axial defocusing position of a current scanning view field can be calculated in real time through pixel offset of a defocusing image in the slice scanning process as long as the linear relation between the axial defocusing displacement and the transverse image offset is calibrated in advance, so that automatic focusing is realized. The method has the defect that the red-green LED illumination and the bright field illumination are required to be switched at high speed when a sample is scanned, so that the scanning time is prolonged. The phase shift detection automatic focusing technology based on single-color double-hole modulation has the basic idea that the axial defocus amount of a sample is converted into the spatial translation of an image in the transverse direction, and the distance of the spatial translation can be calculated through an algorithm based on image registration due to the specific linear relation of the two, so that the corresponding axial defocus amount is deduced. The method can realize real-time automatic focusing by only a single image, but when a sample is out of focus in different positive and negative directions, the camera presents ghost images with the same spatial translation, and at the moment, the positive and negative out-of-focus directions cannot be distinguished.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a phase shift detection auto-focusing device and method for color dual-hole modulation. The technical problems to be solved by the invention are realized by the following technical scheme:
a first aspect of an embodiment of the present invention provides a phase shift detection autofocus device for color dual hole modulation, including: the system comprises a spectroscope, a first barrel lens, a first color image sensor, a distance increasing lens, a double-hole diaphragm, a red light filter, a green light filter, a second barrel lens and a second color image sensor;
the spectroscope, the first cylindrical lens and the first color image sensor are sequentially arranged along the optical axis of the objective lens of the microscope; the first optical axis of the spectroscope is coincident with the optical axis of the objective lens;
the distance increasing mirror, the double-hole diaphragm, the second barrel mirror and the second color image sensor are sequentially arranged along a second optical axis of the spectroscope;
the two small holes of the double-hole diaphragm are symmetrically arranged on two sides of the second optical axis, and the red light filter and the green light filter are respectively arranged in the two small holes.
In one embodiment of the invention, the distance-increasing mirror employs a 4f system.
In one embodiment of the invention, the beam splitter splits the light behind the objective lens into two parts, one part entering the first color image sensor and the other part entering the distance-increasing mirror.
A second aspect of the embodiment of the present invention provides a phase shift detection autofocus method for color dual-hole modulation, which is applied to the autofocus device provided in the first aspect of the embodiment of the present invention, and includes the following steps:
step one, starting from the current field of view of a pathological section sample, acquiring a target color image through a second color image sensor; wherein the target color image is an out-of-focus color image;
step two, obtaining a target image of a red channel and a target image of a green channel of the target color image;
correcting the target image of the red channel and the target image of the green channel according to the color crosstalk coefficient to obtain a corresponding first correction image and a corresponding second correction image;
determining pixel offsets of the first correction image and the second correction image according to the first correction image and the second correction image;
fifthly, determining axial defocus displacement according to the pixel offset and a preset linear relation between the pixel offset and the axial defocus displacement;
step six, controlling the axial electric displacement platform to move to a corresponding quasi-focus position according to the axial defocusing displacement;
step seven, obtaining a quasi-focal image through the first color image sensor;
and step eight, controlling the XY electric displacement platform to move to the next field of view, and repeatedly executing the steps one to seven.
In one embodiment of the present invention, the color crosstalk coefficients include: a first color crosstalk coefficient and a second color crosstalk coefficient;
the expression of the first color crosstalk coefficient is:
the expression of the second color crosstalk coefficient is:
wherein the size of the image is M×N, O 1 An image representing the red channel of the image acquired by the second color image sensor while blocking the green filter, O 2 Is an image of the green channel of the image acquired by the second color image sensor while blocking the red filter, I 1 And I 2 And respectively representing the red channel image and the green channel image of the image acquired by the second color image sensor when the red filter and the green filter are not blocked.
In one embodiment of the invention, the first corrected image is expressed as:
the second correction image is expressed as:
wherein I is R And I G Respectively representing a target image of the red channel and a target image of the green channel.
In one embodiment of the present invention, the specific steps of the fourth step are:
performing Fourier transform on the first correction image and the second correction image respectively to obtain a corresponding first transformation image and a corresponding second transformation image;
conjugation is carried out on the second transformation image to obtain a second conjugation transformation image;
determining a cross-correlation spectrum from the first transformed image and the second conjugate transformed image;
and determining the pixel offset of the first correction image and the second correction image according to the pixel offset between the central peak value and the first-order peak value of the cross-correlation spectrum.
In one embodiment of the present invention, the pixel offset is calculated according to the following formula:
wherein, representRepresenting a first transformed image->Representing a second transformed image->Representing a second conjugate transformed image.
In one embodiment of the invention, the method further comprises:
controlling an axial electric displacement platform to move from a first preset axial defocusing position to a second preset axial defocusing position in a plurality of preset axial defocusing displacements, and acquiring corresponding defocusing color images through the second color image sensor;
acquiring a red channel image and a green channel image of the defocused color image;
correcting the red channel image and the green channel image according to the color crosstalk coefficient to obtain a corresponding first correction defocusing image and a corresponding second correction defocusing image;
determining pixel offsets of the first and second correction defocus images from the first and second correction defocus images;
drawing a scatter diagram of pixel offset and the plurality of preset axial defocus displacements of the first correction defocus image and the second correction defocus image;
and performing curve fitting on the scatter diagram to determine the preset linear relation.
The invention has the beneficial effects that:
according to the invention, the red-green filter is added on the basis of the phase shift detection automatic focusing light path based on single-color double-hole modulation, and a color camera is used for replacing a single-color camera used in the prior art, so that the technical problem that the positive and negative defocusing directions cannot be distinguished in the prior art is solved, and compared with an automatic focusing method based on red-green LED illumination, the automatic focusing method based on red-green LED illumination does not need to switch illumination modes, and the scanning time is saved. The integrated automatic focusing device designed by the invention consists of a distance-increasing mirror, a double-hole diaphragm, a red light filter, a green light filter, a barrel mirror and a color camera, can convert axial defocusing displacement of a pathological section sample into transverse pixel offset between red and green channels of the color camera, and can calculate the pixel offset between the red and green channels by utilizing a relation curve of the pixel offset and the axial defocusing displacement calibrated in advance through an image registration algorithm to reversely solve the defocusing position of the pathological section sample, so that single-frame real-time automatic focusing of a pathological section scanner is realized.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
Fig. 1 is a schematic structural diagram of a phase shift detection auto-focusing device with color dual-hole modulation according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an autofocus principle of a phase shift detection autofocus device with color dual-hole modulation according to an embodiment of the present invention;
FIG. 3 is a flowchart of a phase shift detection auto-focusing method for color dual-hole modulation according to an embodiment of the present invention;
fig. 4 is a calibration curve of the relationship between the pixel offset and the axial defocus displacement of a phase shift detection auto-focusing method for color dual-hole modulation according to an embodiment of the present invention.
Reference numerals illustrate:
1-spectroscope; 2-a first barrel; 3-a first color image sensor; 4-distance increasing mirror; 5-double-hole diaphragm; 6-a red light filter; 7-green light filter; 8-a second barrel; 9-a second color image sensor; 10-objective lens.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but embodiments of the present invention are not limited thereto.
Example 1
As shown in fig. 1, a first aspect of an embodiment of the present invention provides a phase shift detection autofocus device for color dual-hole modulation, including: the device comprises a spectroscope 1, a first barrel lens 2, a first color image sensor 3, a distance increasing lens 4, a double-hole diaphragm 5, a red light filter 6, a green light filter 7, a second barrel lens 8 and a second color image sensor 9. The distance increasing mirror 4, the double-hole diaphragm 5, the red light filter 6, the green light filter 7, the second barrel mirror 8 and the second color image sensor 9 are integrated into an automatic focusing device.
The spectroscope 1, the first barrel lens 2 and the first color image sensor 3 are sequentially arranged along the optical axis of an objective lens 10 of the microscope; the first optical axis of the beam splitter 1 coincides with the optical axis of the objective lens 10. The distance increasing mirror 4, the double-hole diaphragm 5, the second barrel mirror 8 and the second color image sensor 9 are sequentially arranged along the second optical axis of the spectroscope 1. The beam splitter 1 splits the light after the objective lens 10 into two parts, one part enters the first color image sensor 3 along the first optical axis and is responsible for collecting the quasi-focusing image, and the other part enters the automatic focusing device along the second optical axis and is used for calculating the axial defocusing displacement.
The two small holes of the double-hole diaphragm 5 are symmetrically arranged on two sides of the second optical axis, and the red light filter 6 and the green light filter 7 are respectively arranged in the two small holes. The distance increasing mirror 4 adopts a 4f system. The distance increasing mirror 4 comprises two lenses which are sequentially arranged at intervals.
In this embodiment, the function of the macro lens 4 is to delay the fourier plane of the microscope's objective lens 10 from being imaged beyond the objective lens 10. The dual aperture stop has two symmetrical apertures located at equal distances from the central optical axis on the back focal plane of the lens in the add mirror 4 away from the beam splitter 1. The red filter 6 and the green filter 7 filter the brightfield illuminated image separately so that a red-green ghost image is produced on the second color image sensor 9. The second barrel lens 8 focuses the image of the front optical system and the second color image sensor 9 is used to acquire a red-green superimposed image. The device can be compatible with a conventional optical microscope system, and has wide application scene.
In this embodiment, the phase shift detection autofocus principle indicates that the axial defocus displacement of the object is related to the offset distance between the two modulated light beams on the image sensor. In this embodiment, the dual aperture diaphragm 5, the red filter 6 and the green filter 7 are used to modulate the light entering the auto-focusing device, and the images generated by the red filter 6 and the green filter 7 enter the red channel and the green channel of the color image sensor respectively. When the pathological section sample is in the in-focus position, the images of the red channel and the green channel of the second color image sensor 9 will completely coincide, as shown in fig. 2 (a); when the pathological section sample is in the negative defocus position, the overlapping images of the red channel and the green channel are shifted reversely, as shown in fig. 2 (b); when the pathological section sample is in the positive defocus position, the superimposed image of the red channel and the green channel is positively shifted, as shown in fig. 2 (c). The above forward shift refers to the shift of the image of the green channel with respect to the image of the red channel, the value being positive indicating that the image of the green channel is on the same side as the green filter 7; the negative value indicates that the image of the green channel is on the upper side, opposite the green filter 7. From the above, the pixel offset (relative displacement between the red and green channel images) between the red and green channel images of the second color image sensor 9 and the axial defocus displacement of the pathological section sample are in a linear relationship, and by calibrating the linear relationship between the two in advance, the defocus position of the pathological section sample can be calculated by calculating the pixel offset between the red and green channel images of the second color image sensor 9 in real time.
Example two
As shown in fig. 3, a second aspect of the embodiment of the present invention provides a phase shift detection auto-focusing method for color dual-hole modulation, which is applied to the auto-focusing device provided in the first aspect of the embodiment of the present invention, and includes the following steps:
step one, starting from the current field of view of the pathological section sample, a target color image is acquired by the second color image sensor 9. Wherein the target color image is an out-of-focus color image.
And step two, acquiring a target image of a red channel and a target image of a green channel of the target color image.
And thirdly, correcting the target image of the red channel and the target image of the green channel according to the color crosstalk coefficient to obtain a corresponding first correction image and a corresponding second correction image.
And step four, determining pixel offsets of the first correction image and the second correction image according to the first correction image and the second correction image.
And fifthly, determining axial defocus displacement according to the pixel offset and a preset linear relation between the pixel offset and the axial defocus displacement.
And step six, controlling the axial electric displacement platform to move to the corresponding focusing position according to the axial defocusing displacement.
Step seven, a quasi-focal image is acquired by the first color image sensor 3.
And step eight, controlling the XY electric displacement platform to move to the next field of view, and repeatedly executing the steps one to seven.
In this embodiment, by adding the additional red light filter 6 and the green light filter 7 on the conventional phase shift detection autofocus light path and replacing the original monochromatic autofocus camera with a color camera, the problem that the image-based phase shift detection autofocus technology cannot distinguish between the positive and negative defocus directions through a single frame image is solved, and the problem of time waste caused by the need of switching the illumination light sources at high speed in the red-green dual-LED illumination-based autofocus technology is solved. Meanwhile, the integrated automatic focusing device can be used as a plug-and-play plug-in module to be compatible with the existing optical microscope platform, so that the existing optical microscope does not need to be subjected to any hardware change, and the integrated automatic focusing device can be added to comprise an automatic focusing function, thereby having wide application prospect.
In this embodiment, since the response band of the spectral filter in the color camera is not single, the red channel of the camera can respond to the light signal of partial green, and the green channel can also respond to the light signal of partial red, so that color crosstalk occurs between the red and green channels of the camera. In order to ensure the accuracy of the two-channel pixel offset calculation, color crosstalk correction is required after the red-green channel image is extracted. Therefore, before the pathological section scanner starts to work formally, estimation of color crosstalk coefficients and calibration of a preset linear relation curve between pixel offset and axial defocus displacement can be performed in advance.
To calculate the pixel offset (relative displacement) between the two images of the red and green channels, a cross-correlation image registration algorithm is used. The principle is based on an image cross-correlation function, and the relative displacement of two images is determined by calculating the cross-correlation function of the two images. The process of calculating pixel offset by implementing the cross-correlation image registration method is as follows: two images I1 and I2 are provided, and the two images are subjected to Fourier transformation to obtainAnd->For->Conjugation is carried out to obtain->And then->And (3) withMultiplying and performing inverse Fourier transform to obtain cross-correlation spectrum of the two images, and calculating pixel offset between central peak and first-order peak to obtain pixel offset (x j ,y j )：
The specific steps of the invention are described in detail by way of example three:
example III
The invention provides a phase shift detection automatic focusing method for color double-hole modulation, which is applied to an automatic focusing device provided in a first aspect of an embodiment of the invention, and comprises the following steps:
step 301, performing estimation of color crosstalk coefficients:
specifically, the pathological section sample is placed on a microscope, and the small hole on the side of the green light filter 7 is blocked, namely, when only the red light filter 6 works, the green channel of the second color image sensor 9 also has a certain intensity signal. Similarly, the small hole on the side of the red filter 6 is blocked, and when only the green filter 7 is operated, the red channel of the second color image sensor 9 has a certain response. Thus, the model of color crosstalk can be expressed as:
I 1 ＝O 1 +w gr ·O 2 ；
I 2 ＝O 2 +w rg ·O 1 ；
wherein I is 1 And I 2 Respectively representing the red channel and the green channel of the image acquired by the second color image sensor 9 when the red filter 6 and the green filter 7 are simultaneously operated, O 1 Is an image of the red channel of the image acquired by the second color image sensor 9 only when the red filter 6 is in operation, O 2 Is the image of the green channel of the image acquired by the second color image sensor 9 only when the green filter 7 is in operation, w gr And w is equal to rg Representing the first and second color crosstalk coefficients, respectively. If the size of the image is m×n, the expression of the first color crosstalk coefficient is:
the expression of the second color crosstalk coefficient is:
thus, w is obtained according to the above formula gr And w is equal to rg 。
Step 302, calibrating the relationship between the red-green channel image pixel shift (relative displacement) and the axial defocus displacement of the second color image sensor 9. Specifically, step 302 includes steps 3021 to 3026:
in step 3021, the axial electric displacement platform is controlled to move from the first preset axial defocus position to the second preset axial defocus position with a plurality of preset axial defocus displacements, and at the same time, corresponding defocus color images are acquired by the second color image sensor 9, specifically, the axial electric displacement platform is controlled to move from the defocus position of-8 micrometers to the defocus position of +8 micrometers with a 1-micrometer step interval, and at the same time, corresponding defocus color images are acquired by the second color image sensor 9. The plurality of preset axial defocus displacements are sequentially increased from-8 microns by 1 micron to +8 microns.
Step 3022, obtaining a red channel image I of the out-of-focus color image 11 And green channel image I 22 。
Step 3023, correcting the red channel image I according to the two color crosstalk coefficients in step 301 11 And green channel image I 22 Obtaining a corresponding first corrected defocus image I 11,co And a second corrected defocus image I 22,co 。
First corrected out-of-focus image I 11,co Expressed as:
the second corrected out-of-focus image I 22,co Expressed as:
step 3024, determining pixel offsets of the first and second correction defocus images from the first and second correction defocus images. Specifically, based on the above-mentioned cross-correlation image registration algorithm, the calculation formula of the pixel offset in this step is:
step 3025, plotting a scatter plot of the pixel offset and a plurality of preset axial defocus displacements of the first and second correction defocus images.
In step 3026, curve fitting is performed on the scatter plot to obtain linear parameters k and c, and a calibration curve of the relationship between the pixel offset and the axial defocus displacement is determined, as shown in fig. 4, that is, a preset linear relationship is determined.
At step 303, a target color image is acquired by the second color image sensor 9, starting from the current field of view of the pathological section sample. The target color image is an out-of-focus color image, the current field of view in the step is the first field of view, and the image is acquired from the first field of view.
Step 304, obtaining a target image I of a red channel of the target color image R And a target image I of the green channel G 。
Step 305, correcting the target image I of the red channel according to the color crosstalk coefficient R And a target image I of the green channel G Obtaining a corresponding first corrected image I R,co And a second correction image I G,co . First corrected image I R,co For the corrected image of the red channel, a second corrected image I G,co A corrected image for the green channel. In this step, the image correction is performed according to the two color crosstalk coefficients in step 301, and the first corrected image is expressed as:
the second correction image is expressed as:
step 306, determining pixel offsets of the first correction image and the second correction image according to the first correction image and the second correction image. Specifically, step 306 includes steps 3061-3064:
step 3061 for the first corrected image I R,co And a second correction image I G,co Respectively performing Fourier transform to obtain corresponding first transformed imagesAnd a second transformed image->Wherein image I is a shorthand version of image I (a, b).
Step 3062, for the second transformed imageConjugation to obtain the second conjugate transformed image +.>
Step 3063, based on the first transformed imageAnd a second conjugate transformed image->Determining a first transformed image +.>And a second transformed image->Cross-correlation of (2)A spectrum.
Step 3064, determining pixel offsets of the first correction image and the second correction image according to pixel offsets between the center peak and the first-order peak of the cross-correlation spectrum.
To sum up, the pixel offset (a j ,b j ) The calculation formula of (2) is as follows:
step 307, determining the axial defocus displacement according to the pixel offset and the preset linear relationship between the pixel offset and the axial defocus displacement. In this step, the axial defocus displacement can be calculated according to the linear parameters k and c and the pixel shift of the preset linear relationship in step 302.
And step 308, controlling the axial electric displacement platform to move to the corresponding focusing position according to the axial defocusing displacement, and completing automatic focusing.
In step 309, a quasi-focal image is acquired by the first color image sensor (3).
Step 310, the XY motorized displacement stage is controlled to move to the next field of view, and steps 303-309 are repeated.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Further, one skilled in the art can engage and combine the different embodiments or examples described in this specification.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (9)
1. A phase shift detection autofocus device for color dual hole modulation comprising: the device comprises a spectroscope (1), a first barrel lens (2), a first color image sensor (3), a distance increasing lens (4), a double-hole diaphragm (5), a red light filter (6), a green light filter (7), a second barrel lens (8) and a second color image sensor (9);
the spectroscope (1), the first cylindrical lens (2) and the first color image sensor (3) are sequentially arranged along the optical axis of an objective lens (10) of the microscope; the first optical axis of the spectroscope (1) coincides with the optical axis of the objective lens (10);
the distance increasing mirror (4), the double-hole diaphragm (5), the second cylindrical mirror (8) and the second color image sensor (9) are sequentially arranged along a second optical axis of the spectroscope (1);
the two small holes of the double-hole diaphragm (5) are symmetrically arranged on two sides of the second optical axis, and the red light filter (6) and the green light filter (7) are respectively arranged in the two small holes.
2. A phase shift detection autofocus device for color dual hole modulation according to claim 1, characterized in that said distance-increasing mirror (4) employs a 4f system.
3. A phase shift detection autofocus device according to claim 1, characterized in that the beam splitter (1) splits the light behind the objective lens (10) in two, one part entering the first color image sensor (3) and the other part entering the distance increasing mirror (4).
4. A phase shift detection auto-focusing method of color dual-aperture modulation, applied to an auto-focusing device as claimed in any one of claims 1 to 3, comprising the steps of:
step one, starting from the current field of view of the pathological section sample, acquiring a target color image through a second color image sensor (9); wherein the target color image is an out-of-focus color image;
step two, obtaining a target image of a red channel and a target image of a green channel of the target color image;
correcting the target image of the red channel and the target image of the green channel according to the color crosstalk coefficient to obtain a corresponding first correction image and a corresponding second correction image;
determining pixel offsets of the first correction image and the second correction image according to the first correction image and the second correction image;
fifthly, determining axial defocus displacement according to the pixel offset and a preset linear relation between the pixel offset and the axial defocus displacement;
step six, controlling the axial electric displacement platform to move to a corresponding quasi-focus position according to the axial defocusing displacement;
step seven, acquiring a quasi-focal image through the first color image sensor (3);
and step eight, controlling the XY electric displacement platform to move to the next field of view, and repeatedly executing the steps one to seven.
5. The method for phase shift detection autofocus for color dual hole modulation of claim 4, wherein said color crosstalk coefficients comprise: a first color crosstalk coefficient and a second color crosstalk coefficient;
the expression of the first color crosstalk coefficient is:
the expression of the second color crosstalk coefficient is:
wherein the size of the image is M×N, O 1 An image representing the red channel of the image acquired by the second color image sensor (9) while blocking the green filter (7), O 2 Is an image of the green channel of the image acquired by the second color image sensor (9) while blocking the red filter, I 1 And I 2 And respectively representing the red channel image and the green channel image of the image acquired by the second color image sensor (9) when the red filter (6) and the green filter (7) are not blocked.
6. The method of claim 4, wherein the first corrected image is represented as:
the second correction image is expressed as:
wherein I is R And I G Respectively representing a target image of the red channel and a target image of the green channel.
7. The method for phase shift detection and auto-focusing of color dual-aperture modulation of claim 4, wherein the specific steps of step four are:
performing Fourier transform on the first correction image and the second correction image respectively to obtain a corresponding first transformation image and a corresponding second transformation image;
conjugation is carried out on the second transformation image to obtain a second conjugation transformation image;
determining a cross-correlation spectrum from the first transformed image and the second conjugate transformed image;
and determining the pixel offset of the first correction image and the second correction image according to the pixel offset between the central peak value and the first-order peak value of the cross-correlation spectrum.
8. The method for auto-focusing for phase shift detection of color bi-aperture modulation of claim 4, wherein the pixel offset is calculated by the formula:
wherein, representRepresenting a first transformed image->A second transformed image is represented and is displayed,representing a second conjugate transformed image.
9. The method of phase shift detection autofocus for color dual hole modulation of claim 8, further comprising:
controlling the axial electric displacement platform to move from a first preset axial defocusing position to a second preset axial defocusing position in a plurality of preset axial defocusing displacements, and acquiring corresponding defocusing color images through the second color image sensor (9);
acquiring a red channel image and a green channel image of the defocused color image;
correcting the red channel image and the green channel image according to the color crosstalk coefficient to obtain a corresponding first correction defocusing image and a corresponding second correction defocusing image;
determining pixel offsets of the first and second correction defocus images from the first and second correction defocus images;
drawing a scatter diagram of pixel offset and the plurality of preset axial defocus displacements of the first correction defocus image and the second correction defocus image;
and performing curve fitting on the scatter diagram to determine the preset linear relation.
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