CN111308741B - Small concave imaging device and imaging method based on liquid crystal lens - Google Patents
Small concave imaging device and imaging method based on liquid crystal lens Download PDFInfo
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- CN111308741B CN111308741B CN201811519445.5A CN201811519445A CN111308741B CN 111308741 B CN111308741 B CN 111308741B CN 201811519445 A CN201811519445 A CN 201811519445A CN 111308741 B CN111308741 B CN 111308741B
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- G—PHYSICS
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/1313—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells specially adapted for a particular application
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
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- H—ELECTRICITY
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- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
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Abstract
The embodiment of the invention discloses a small concave imaging device and an imaging method based on a liquid crystal lens. The foveal imaging device comprises: the wide-field-angle lens assembly is used for imaging a scene in a field range, and the liquid crystal lens assembly focuses on a specified partial scene in the scene to form a focused image. The invention solves the imaging requirement of large visual field and high resolution at the same time, and has the advantages of large visual field, high definition of interested region and simple structure.
Description
Technical Field
The invention relates to the technical field of optical imaging, in particular to a small concave imaging device and an imaging method based on a liquid crystal lens.
Background
At present, in the technical fields such as target tracking and positioning, scanning and identification, a fast and light imaging system with a large field of view and high resolution is increasingly emphasized. In conventional imaging systems, the larger the field angle, the poorer the imaging quality of the marginal field. As shown in fig. 1, for the purpose of balancing the overall image quality, a position with the best overall image quality is generally selected as an image plane, rather than selecting the best image plane for a single field of view. From fig. 1, it can be found that: in conventional imaging systems, the resolution of certain regions is often sacrificed in order to achieve a large field of view. In conventional optical imaging systems, in order to obtain a large field of view and high resolution, a method of reducing the diameter of the entrance pupil and increasing the number of optical elements is generally used. However, reducing the entrance pupil diameter reduces the illuminance of the image plane; adding optical elements increases the volume and weight of the system. These all limit further application of the technology.
Foveated imaging optics is one of the most promising future solutions to the demands of large field of view, high resolution, lightweight and compact imaging applications. The fovea imaging simulates the characteristics of an eye imaging system, namely global imaging can be carried out on a large view field, high-resolution local imaging can be realized on an interested region, and the characteristics of the large view field and the high resolution are considered.
In the current field of image capture, the resolution of an optical lens is already as high as several tens of millions of pixels, but in real-time video transmission, only several millions of pixels can be transmitted, even lower, which is mainly limited by the data volume transmission. Even if ten million cameras are used as video recording devices, in real-time transmission, high-pixel video streams are often compressed by a high compression ratio, so that actual pixels are often much lower.
The liquid crystal lens is a device capable of adjusting the focal length by controlling the voltage for driving the liquid crystal, and has the advantages of small mass, low power consumption, small volume, real-time control and the like. The liquid crystal lens and the lens group with the large view field are combined for use, the concept of foveal imaging is referred, namely the lens with the large view field performs global imaging, and the liquid crystal lens performs high-resolution imaging on an interested area, so that the imaging system with the large view field, the high resolution, the high speed and the light weight is realized. Compared with a spatial light modulator, the liquid crystal lens does not need to consider incident wavelength, has stronger adjusting capability and can correct the aberration caused by defocusing.
At present, research on the foveal imaging of the liquid crystal lens in the image field is rare, and the realization of the foveal imaging by using the liquid crystal lens also faces a plurality of technical problems. Therefore, it is necessary to provide a foveal imaging device and an imaging method based on a liquid crystal lens to realize foveal imaging.
Disclosure of Invention
In view of this, embodiments of the present invention provide a foveal imaging apparatus and an imaging method based on a liquid crystal lens, so as to implement foveal imaging with low power consumption and high imaging quality.
In a first aspect, the present invention provides a liquid crystal lens based foveal imaging device comprising: the wide-field-angle lens assembly is used for imaging a scene in a field range, and the liquid crystal lens assembly focuses on a specified partial scene in the scene to form a focused image.
Further, the distance d between the liquid crystal lens assembly and the image sensor is as follows:
d≤D*m；
wherein D is the aperture of the liquid crystal lens assembly, and m is the aperture value of the large-field-angle lens assembly.
Further, the liquid crystal lens assembly comprises a liquid crystal lens unit and a driving control unit, when focusing is performed, the driving control unit controls the liquid crystal lens unit to work in a first focal power mode, the image processor judges whether the image quality is improved, and if the image quality is improved, the focusing on the local scene is completed; and if the image quality is not improved, the driving control unit controls the liquid crystal lens unit to work in a second focal power mode until the image quality is improved and the focusing on the local scene is finished.
Optionally, the liquid crystal lens unit is a non-array liquid crystal lens, and the non-array liquid crystal lens can move along an optical axis or a direction perpendicular to the optical axis according to the local scene imaging area.
Optionally, the liquid crystal lens unit is a liquid crystal lens array including a plurality of sub-lenses;
when focusing, the driving control unit controls the sub-lens corresponding to the local scene imaging area in the liquid crystal lens array to focus on the local scene to generate a local focusing image;
or, during focusing, the driving control unit controls the sub-lenses corresponding to the local scene imaging areas in the liquid crystal lens array to focus on the local scenes with different object distances, so as to generate a panoramic deep image.
Further, the image processor is further configured to distinguish a focused region from an unfocused region of the focused image, perform high compression ratio compression on the unfocused region, and perform lossless or low-loss compression on the focused region.
In another aspect, the present invention provides a method for forming a concave image based on a liquid crystal lens, where the method is applied to the above-mentioned local imaging device based on a liquid crystal lens, and the method includes:
controlling the large field angle lens assembly to image a scene over a field of view;
and controlling the liquid crystal lens assembly to focus on the appointed local scene in the scene to form focusing imaging.
Further, the liquid crystal lens assembly includes a liquid crystal lens unit and a driving control unit, the liquid crystal lens unit is a non-array liquid crystal lens, the non-array liquid crystal lens can move along an optical axis or a vertical optical axis direction according to the local scene imaging area, the controlling the liquid crystal lens assembly to focus on a specified local scene in the scene to form focused imaging includes:
determining a local scene imaging area;
moving the non-array liquid crystal lens to the local scene imaging area;
and controlling the non-array liquid crystal lens to focus on the local scene imaging area.
Further, the liquid crystal lens unit is a liquid crystal lens array comprising sub-lenses; the controlling the liquid crystal lens assembly to focus on the appointed local scene in the scene to form focused imaging comprises the following steps:
determining a sub-lens corresponding to the local scene;
controlling the sub-lens to focus on the local scene imaging area to generate a local focusing image;
or, the controlling the liquid crystal lens assembly to focus on a specified local scene in the scene to form focused imaging includes:
determining a sub-lens corresponding to the local scene;
and controlling the sub-lens to focus the local scenes with different object distances to generate a panoramic deep image.
Further, the method further comprises:
distinguishing between in-focus and out-of-focus regions of the in-focus image,
and compressing the non-focusing area at a high compression ratio, and compressing the focusing area at a lossless or low loss.
The small concave imaging device and the imaging method based on the liquid crystal lens have the following advantages:
1) the imaging requirements of large field of view and local high resolution can be simultaneously realized;
2) the liquid crystal lens is small in size, light and thin, and the complexity of the system cannot be increased;
3) local focusing is realized by using the array device, so that the flexibility is better, and full-depth-of-field imaging can be realized;
4) the problem of data volume too big when solving high definition video transmission, can extensively be used for monitoring etc. and need carry out real-time video transmission's field for a long time.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of a preferred imaging plane selection in a conventional optical system;
fig. 2 is a schematic structural diagram of a liquid crystal lens-based foveal imaging device according to a first embodiment of the present invention;
FIG. 3a is a schematic diagram illustrating an image of a liquid crystal lens during operation according to a first embodiment of the present invention;
FIG. 3b is a schematic diagram illustrating a selection of an optimal image plane when the liquid crystal lens operates according to a first embodiment of the invention;
FIG. 4a is a schematic diagram illustrating an imaging of a liquid crystal lens array of a concave-convex imaging device based on a liquid crystal lens according to a second embodiment of the present invention when the liquid crystal lens array does not operate;
FIG. 4b is a schematic diagram showing an imaging operation of a liquid crystal lens array in a liquid crystal lens-based foveal imaging device according to a second embodiment of the present invention;
FIG. 5a is a schematic diagram illustrating an imaging process when the object distance is different and the liquid crystal lens array does not operate in the liquid crystal lens-based foveal imaging apparatus according to the second embodiment of the present invention;
FIG. 5b is a schematic diagram of an imaging process when the object distance is different and the liquid crystal lens array does not operate in the foveal imaging device based on the liquid crystal lens according to the second embodiment of the present invention;
fig. 6 shows a flowchart of foveal imaging based on a liquid crystal lens according to a third embodiment of the present invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Example one
Referring to fig. 2, a foveal imaging device based on a liquid crystal lens according to a first embodiment of the present invention includes: a liquid crystal lens assembly 20, a large field angle lens assembly 10, an image sensor 40, and an image processor 50. The liquid crystal lens assembly 20 is positioned between the large field angle lens assembly 10 and the image sensor 40. The liquid crystal lens assembly 20 includes a liquid crystal lens unit 201 and a driving control unit 202, wherein an aperture of the liquid crystal lens assembly 20, that is, the liquid crystal lens unit 201, is smaller than an aperture of the large-field-angle lens assembly 10, the large-field-angle lens assembly 10 images a scene in a field range, and the liquid crystal lens assembly 20 focuses on a specified partial scene in the scene to form a focused image.
The lc lens unit 201 in this embodiment is a non-array lc lens, and the lc lens unit 201 may be an assembly of a plurality of lc lenses or a single lc lens. Further, the non-array liquid crystal lens can move along the optical axis or the direction perpendicular to the optical axis according to the local scene imaging area. The imaging plane is a plane parallel to the imaging plane of the image sensor 40. In this way, the liquid crystal lens unit 201 can be moved to the local scene imaging area of interest to the user, thereby focusing the region-of-interest image. Specifically, the liquid crystal lens unit 201 can be moved along the optical axis or in the direction perpendicular to the optical axis by a mechanical means such as a pulley or a slide rail.
In the first embodiment of the present invention, the liquid crystal lens assembly 20 and the large field angle lens assembly 10 are used in combination, and the liquid crystal lens assembly 20 is located in front of the image sensor 40 and behind the last lens of the large field angle lens assembly 10, so that the foveal imaging can be realized, the imaging requirement of large field of view and high resolution is met, and meanwhile, the liquid crystal lens has the advantages of small size, light weight, low power consumption, and the like, so that the structural complexity of the whole foveal imaging device cannot be increased.
When the liquid crystal lens assembly 20 is in a non-lens working state, after the point of the central field of view and the point of the edge field of view pass through the large-field-angle lens assembly 10 according to the embodiment of the present invention, the light rays do not converge on the imaging surface, and a defocusing phenomenon occurs, and at this time, the imaging surface presents a discrete image spot. No sharp image is presented on the image plane. Through the liquid crystal lens assembly of the present invention, on one hand, the image quality reduction caused by defocus can be corrected, as shown in fig. 3a, when the large-field-angle lens assembly 10 is in a defocus state and the liquid crystal lens assembly 20 is in a lens state, a point (a local scene point or area) of the central field of view enters the liquid crystal lens assembly 20 after passing through the large-field-angle lens assembly 10 of the embodiment of the present invention, and after passing through the liquid crystal lens assembly 20, the point (the local scene point or area) of the central field of view is clearly imaged on the image plane, while a point (a point or area which does not need to be focused) of the edge field of view does not pass through the liquid crystal lens assembly, but directly forms a blurred image on the image plane. Thus, the foveal imaging effect is achieved, focusing on the local scene area in which the user is interested, and forming a blurred image for the area not concerned by the user. On the other hand, the optimal image plane of the imaging device is between the edge-field optimal image plane and the center-field optimal image plane. As shown in fig. 3b, high resolution imaging of the local scene region of interest can be achieved at the best image plane without changing the imaging of other regions.
The position where the liquid crystal lens assembly 20 is placed in the optical path: the focal length of the large-field-angle lens assembly 10 is f, the aperture value F.no is m, the aperture of the liquid crystal lens assembly 20 is D, and the entrance pupil of the large-field-angle lens assembly 10 is
In order to protect the liquid crystal lens assembly 20 from stray light during use, the image of the liquid crystal lens assembly 20 with respect to the large field angle lens assembly 10 should be larger than
The liquid crystal lens assembly 20 has a magnification of
d is the distance from the liquid crystal lens assembly 20 to the image sensor 40, and is required to be
I.e. D is less than or equal to D m.
Therefore, the liquid crystal lens assembly 20 should be disposed at a position within a distance D × m from the image sensor 40, and it is preferable that the liquid crystal lens assembly 20 is disposed at a distance D × m from the image sensor 40.
In an embodiment, the liquid crystal lens assembly 20 of this embodiment includes a liquid crystal lens unit and a driving control unit, when focusing, the driving control unit controls the liquid crystal lens unit to work in a first focal power mode, the image processor determines whether the image quality is improved, and if the image quality is improved, the focusing on the local scene is completed; and if the image quality is not improved, the driving control unit controls the liquid crystal lens unit to work in a second focal power mode until the image quality is improved and the focusing on the local scene is finished. In a specific embodiment, the image quality is described by taking an image contrast as an example, when focusing, the driving control unit 202 controls the liquid crystal lens unit 201 to work in a first focal power mode, the image processor 50 determines whether the image contrast is improved, and if the image contrast is improved, the highest position of the contrast is searched for, and the focusing on the local scene is completed; if the contrast of the image is not improved, the driving control unit 202 controls the liquid crystal lens unit to work in the form of the second focal power, and the image processor 50 searches for the highest position of the contrast to complete focusing on the local scene. In addition, whether the image quality is improved or not can be judged by the following methods: for the same image and the same region, the higher the contrast is, the clearer the image is; by judging the entropy, when the entropy is larger, the image is clearer; by judging the gray gradient of the image, if the gray gradient value is larger, the image is clearer; it is also possible to determine the high frequency components of the image, and if the high frequency components are more, the image is clearer.
For example, the driving control unit 202 may control the focus of the liquid crystal lens unit 201 by changing the driving voltage of the liquid crystal lens unit 201 using a hill climbing method. It is obvious that the invention is not limited to hill climbing. The first focal power and the second focal power are two groups of focal powers with different numerical values, and can be the maximum positive focal power, the maximum negative focal power or any focal power between the maximum positive focal power and the maximum negative focal power.
Specifically, in the embodiment of the present invention, the operation mode of the liquid crystal lens-based foveal imaging device is summarized as follows:
1. when the large-field angle lens assembly 10 of the foveal imaging device based on the liquid crystal lens in the present embodiment is in normal focusing, the liquid crystal lens assembly 20 does not work;
2. when the foveal imaging device based on the liquid crystal lens in this embodiment is in a defocused state, the liquid crystal lens assembly 20 works, and the liquid crystal lens assembly 20 adopts an auto-focusing method: for example, the liquid crystal lens unit 201 is operated with a first focal power, such as a maximum negative focal power, at this time, the driving control unit 202 controls the first electrode pair of the liquid crystal lens unit 201, the first electrode driving voltage V1 < the second electrode driving voltage V2, and V1 is gradually increased until V1 is equal to V2, and it is determined whether the image quality (for example, the image contrast) is improved, and if the image contrast is improved, the highest position of the image contrast is searched, and then the local focusing is completed. If the image contrast is not improved, the driving control unit 202 operates the liquid crystal lens unit 201 with the second focal power, for example, the maximum positive focal power, at this time, the first electrode driving voltage V1 > the driving voltage V2 of the second electrode in the first electrode pair of the liquid crystal lens unit 201, and gradually increases V2 until V1 is equal to V2, and finds the position with the maximum image contrast, thereby completing focusing.
In another embodiment, when the liquid crystal lens assembly 20 focuses, the driving control unit 202 controls the liquid crystal lens unit 201 to work in the form of maximum positive focal power by a hill-climbing method, the image processor 50 determines whether the contrast of the image is improved, and if the contrast of the image is improved, searches for the highest position of the contrast, and completes the focusing on the local scene; if the contrast of the image is not improved, the driving control unit 202 controls the liquid crystal lens unit to work in the form of the maximum negative focal power by a hill climbing method, and the image processor 50 searches for the highest position of the contrast to complete focusing on the local scene. The specific implementation process may refer to the previous embodiment, and is not described herein again.
Further, in this embodiment, after the focusing on the local scene area is completed according to any of the above manners, the liquid crystal lens assembly 20 keeps working; the image processor 50 distinguishes a focusing region and a non-focusing region of the focused image, specifically, the image processor 50 judges a position of abrupt change of image gray gradient or a position of abrupt change of image contrast through an algorithm, the regions surrounded by the positions are the focusing regions, and the parts outside the focusing regions are the non-focusing regions; and compressing the non-focusing area at a high compression ratio, greatly reducing the overall data volume, and compressing the focusing area at a lossless or low loss to realize a high-definition video of the region of interest.
Example two
The difference between the foveola imaging device based on the liquid crystal lens in the second embodiment of the invention and the first embodiment is that: the liquid crystal lens unit 201 is a liquid crystal lens array including a plurality of sub-lenses.
In a focusing manner, the driving control unit 202 controls sub-lenses corresponding to local scene imaging areas in the liquid crystal lens array to focus on the local scene, so as to generate a local focusing image;
in a specific implementation, the lc lens cell 201 may employ an M × M lc lens array; the overall image display area is divided into M2 sub-areas with some overlap between the sub-areas. Taking the liquid crystal lens array of 3 × 3 as an example, the whole display area is divided into nine sub-areas, and one sub-area corresponds to one sub-lens in the liquid crystal lens array. Controlling sub-lenses corresponding to local scene imaging areas in the liquid crystal lens array to focus on the local scenes, so that local focusing images can be generated; referring to fig. 4a and 4b, in fig. 4a, the liquid crystal lens array does not operate, the point of the central field of view and the point of the peripheral field of view enter the liquid crystal lens array after passing through the large field angle lens assembly 10, then a divergent image spot is formed at the sensor position, and the image sensor 50 at the sensor position obtains an unclear image. In fig. 4b, the liquid crystal lens array is in a working state, the point of the central field of view and the point of the peripheral field of view enter the liquid crystal lens array after passing through the large-field-angle lens assembly 10, and then a clear image is formed at the sensor position, and the image sensor 50 at the sensor position obtains an enlarged and clear focused image.
In another focusing manner, the driving control unit 202 controls sub-lenses corresponding to local scene imaging areas in the liquid crystal lens array to focus on the local scenes with different object distances, so as to generate a panoramic deep image. The panoramic deep image is that all areas of the image are focused accurately, that is, the image has no background blurring effect, and all objects in the image are clear.
In this embodiment, the field points at different object distance positions in the scene are focused and imaged, where the point of the central field and the point of the peripheral field are not at the same object distance object plane position as shown in fig. 4a and 4b, but at different object distance object plane positions as shown in fig. 5a and 5b, if the liquid crystal lens array is a 3 × 3 array, the image is divided into 9 parts, and when adjacent liquid crystal lenses are simultaneously opened, the images are overlapped, and a jigsaw puzzle is required to eliminate the overlapped area. In the embodiment, the sub-lenses corresponding to the local scene areas in which the user is interested are controlled to focus according to different object distance positions, so that the full depth of field can be realized. In fig. 5a the liquid crystal lens array is not operating and the image sensor 50 with the point of the central field and the point of the peripheral field at the sensor position gets an unsharp image. In fig. 5b, the liquid crystal lens array is in a working state, the point of the central view field and the point of the edge view field enter the liquid crystal lens array after passing through the large-field-angle lens assembly 10, the sub-lenses corresponding to the local scene area in the lens array are controlled to focus according to different object distance positions, then a clear image is formed at the sensor position, and the image sensor 50 at the sensor position obtains an enlarged and clear focused image.
EXAMPLE III
Based on the foveal imaging device based on the liquid crystal lens in the first embodiment and the second embodiment, the third embodiment of the present invention correspondingly provides a foveal imaging method based on a liquid crystal lens, as shown in fig. 6, the method includes:
s1, controlling the large-field-angle lens assembly to image the scene in the field range;
and S2, controlling the liquid crystal lens assembly to focus the appointed local scene in the scene to form focusing imaging.
In one embodiment, the liquid crystal lens assembly includes a liquid crystal lens unit and a driving control unit, the liquid crystal lens unit is a non-array liquid crystal lens, the non-array liquid crystal lens is movable along an optical axis or a vertical optical axis direction according to the local scene imaging area, the controlling the liquid crystal lens assembly to focus on a specified local scene in the scene to form focused imaging includes:
s21, determining a local scene imaging area;
s22, moving the non-array liquid crystal lens to the local scene imaging area;
and S23, controlling the non-array liquid crystal lens to focus on the local scene imaging area.
In another embodiment, the liquid crystal lens cell is a liquid crystal lens array including sub-lenses; the controlling the liquid crystal lens assembly to focus on the appointed local scene in the scene to form focused imaging comprises the following steps:
determining a sub-lens corresponding to the local scene;
controlling the sub-lens to focus on the local scene imaging area to generate a local focusing image;
or, the controlling the liquid crystal lens assembly to focus on a specified local scene in the scene to form focused imaging includes:
determining a sub-lens corresponding to the local scene;
and controlling the sub-lens to focus the local scenes with different object distances to generate a panoramic deep image.
S3, distinguishing the focusing area and the non-focusing area of the focusing image,
specifically, the position of the abrupt change of the image gray gradient or the position of the abrupt change of the image contrast is judged through an algorithm, the area enclosed by the positions is a focusing area, and the part outside the focusing area is a non-focusing area.
And S4, compressing the non-focusing area at a high compression ratio, and compressing the focusing area at a lossless or low loss.
In this embodiment, the non-focusing region is compressed at a high compression ratio, so that the global data amount is greatly reduced, and the focusing region is compressed at a lossless or low loss, so as to implement a high-definition video of the region of interest.
The small concave imaging device and the imaging method based on the liquid crystal lens have the following advantages:
1. the imaging requirements of large field of view and local high resolution can be simultaneously realized;
2. the liquid crystal lens is small in size, light and thin, and the complexity of the system is not increased;
3. local focusing is realized by using the array device, so that the flexibility is better, and full-depth-of-field imaging can be realized;
4. the problem of data volume too big when solving high definition video transmission, can extensively be used for monitoring etc. and need carry out real-time video transmission's field for a long time.
It is to be understood that the invention is not limited to the specific arrangements and instrumentality described above and shown in the drawings. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.
The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.
It should also be noted that the exemplary embodiments mentioned in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.
As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.
Claims (7)
1. A liquid crystal lens-based foveal imaging device, comprising: the wide-field-angle lens assembly is used for imaging scenes in a field range, the liquid crystal lens assembly focuses a specified local scene in the scenes to form a focused image, the wide-field-angle lens assembly performs global imaging, and the liquid crystal lens assembly performs high-resolution imaging on an interested area; the liquid crystal lens assembly comprises a liquid crystal lens unit which is a non-array liquid crystal lens, and the non-array liquid crystal lens moves along the direction of a vertical optical axis according to the local scene imaging area; the points of the central field of view are imaged sharply on the image plane, while the points of the peripheral field of view are imaged blurred on the image plane.
2. The liquid crystal lens-based foveal imaging device of claim 1, wherein the distance d of said liquid crystal lens assembly from said image sensor is:
d≤D*m；
wherein D is the aperture of the liquid crystal lens assembly, and m is the aperture value of the large-field-angle lens assembly.
3. The device as claimed in claim 1, wherein the liquid crystal lens assembly comprises a driving control unit, and when focusing, the driving control unit controls the liquid crystal lens unit to work in a first focal power mode, the image processor determines whether the image quality is improved, and if the image quality is improved, the focusing on the local scene is completed; and if the image quality is not improved, the driving control unit controls the liquid crystal lens unit to work in a second focal power mode until the image quality is improved and the focusing on the local scene is finished.
4. The lc lens based foveal imaging device of any of claims 1-3, wherein said image processor is further configured to distinguish between in-focus and out-of-focus regions of said in-focus image, compress said out-of-focus regions at a high compression ratio, and compress said in-focus regions at a lossless or low loss.
5. A liquid crystal lens-based foveal imaging method, characterized in that said method is applied in a liquid crystal lens-based foveal imaging device according to claim 1, said method comprising:
controlling the large field angle lens assembly to image a scene over a field of view;
and controlling the liquid crystal lens assembly to focus on the appointed local scene in the scene to form focusing imaging.
6. The liquid crystal lens-based foveal imaging method according to claim 5, wherein the liquid crystal lens assembly comprises a liquid crystal lens unit and a driving control unit, the liquid crystal lens unit is a non-array liquid crystal lens, the non-array liquid crystal lens can move along an optical axis or a vertical optical axis direction according to the local scene imaging area, the controlling the liquid crystal lens assembly to focus on a specified local scene in the scene to form in-focus imaging comprises:
determining a local scene imaging area;
moving the non-array liquid crystal lens to the local scene imaging area;
and controlling the non-array liquid crystal lens to focus on the local scene imaging area.
7. The liquid crystal lens-based foveal imaging method of any of claims 5-6, characterized in that said method further comprises:
distinguishing between in-focus and out-of-focus regions of the in-focus image,
and compressing the non-focusing area at a high compression ratio, and compressing the focusing area at a lossless or low loss.
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| CN201811519445.5A CN111308741B (en) | 2018-12-12 | 2018-12-12 | Small concave imaging device and imaging method based on liquid crystal lens |
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| JP2005208626A (en) * | 2003-12-24 | 2005-08-04 | Nikon Corp | Microscope and immersion objective lens |
| JP2007328163A (en) * | 2006-06-08 | 2007-12-20 | Canon Inc | Zoom lens and image projection device having the same |
| JP5080414B2 (en) * | 2008-09-30 | 2012-11-21 | 富士通フロンテック株式会社 | Imaging device for reading information |
| CN104007559B (en) * | 2014-05-08 | 2017-05-17 | 北京理工大学 | Foveated imaging system with partial super-resolution scanning function |
| CN104102018B (en) * | 2014-05-08 | 2016-10-05 | 北京理工大学 | Double small recessed local high resolution imaging system |
| CN105301864B (en) * | 2014-07-29 | 2018-01-30 | 深圳市墨克瑞光电子研究院 | Liquid crystal lens imaging device and liquid crystal lens imaging method |
| CN104506846B (en) * | 2014-12-27 | 2017-01-25 | 北京智谷睿拓技术服务有限公司 | High-resolution display control method and device |
| CN106610542B (en) * | 2015-10-21 | 2019-09-10 | 深圳超多维科技有限公司 | Liquid crystal microlens array imaging device and imaging method |
| CN105827922B (en) * | 2016-05-25 | 2019-04-19 | 京东方科技集团股份有限公司 | A kind of photographic device and its image pickup method |
| CN108206902B (en) * | 2016-12-16 | 2020-09-22 | 深圳超多维科技有限公司 | Light field camera |
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