CN107300827B - Low noise lensless imaging method - Google Patents
Low noise lensless imaging method Download PDFInfo
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- CN107300827B CN107300827B CN201710542672.9A CN201710542672A CN107300827B CN 107300827 B CN107300827 B CN 107300827B CN 201710542672 A CN201710542672 A CN 201710542672A CN 107300827 B CN107300827 B CN 107300827B
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B41/00—Special techniques not covered by groups G03B31/00 - G03B39/00; Apparatus therefor
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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
- G02F3/00—Optical logic elements; Optical bistable devices
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Abstract
The invention discloses a low-noise lens-free imaging method, which comprises the following steps: after the detector is electrified, recording light rays emitted by the target and passing through the coding template, and reconstructing an image of the target after the output pattern is subjected to related processing with the coding pattern; the size of the effective area array of the detector is larger than half of the size of the pattern of the coding template; the coding template is a coding pattern etched by utilizing an etching technology after a metal film is plated on a glass substrate, the coding pattern is composed of a plurality of light-transmitting and light-non-transmitting square units with the same size, the distribution of the square units is represented by a matrix generated by the outer product of two pseudo-random vectors composed of 0 and 1, 0 and 1 in the matrix respectively represent that light cannot be transmitted and light cannot be transmitted in the coding pattern, and the number of the light-non-transmitting square units is larger than that of the light-transmitting square units. The scheme is based on a specific coding template, and can solve the problem of noise sensitivity of a lensless camera based on a URA template, so that the signal-to-noise ratio of a reconstructed image is improved.
Description
Technical Field
The invention relates to the technical field of lens-free imaging, in particular to a low-noise lens-free imaging method.
Background
The lens-free imaging is a technology for realizing indirect imaging by using a special template to replace a traditional lens. The principle is that after light emitted by a luminous point passes through a template, a corresponding shadow pattern is projected on a detector, the shadow pattern records the position and luminous intensity information of the luminous point, and the positions are different and the patterns are also different. The different patterns are uncorrelated. The detector records the superposed patterns, and the intensities of the luminous points at different positions can be solved through correlation operation, so that corresponding images are obtained.
The current templates have various forms, including fresnel zone plates, URAs, random binary coding templates, etc. The URA is a form of performance that is better because it has half the area that is transparent and its point spread function is very close to the impact function, making it an ideal solution.
As shown in fig. 1, a schematic diagram of lensless imaging using a URA template is shown. Half of its area is transparent with high luminous flux, but the URA-based lensless camera is relatively sensitive to noise, which affects the signal-to-noise ratio of the final reconstructed image.
Disclosure of Invention
The invention aims to provide a low-noise lens-free imaging method which can effectively reduce the sensitivity of the current lens-free camera based on a URA coding template to noise.
The purpose of the invention is realized by the following technical scheme:
a low noise lensless imaging method, comprising:
after the detector is electrified, recording light rays emitted by the target and passing through the coding template, and reconstructing an image of the target after the output pattern is subjected to related processing with the coding pattern;
wherein the detector effective area array size is larger than half of the coding template pattern size;
the coding template is a coding pattern etched by utilizing an etching technology after a metal film is plated on a glass substrate, the coding pattern is composed of a plurality of light-transmitting and light-proof square units with the same size, the distribution of the square units is represented by a matrix generated by the outer product of two pseudo-random vectors composed of 0 and 1, 0 and 1 in the matrix respectively represent that the coding pattern cannot transmit light and can transmit light, wherein the number of the light-transmitting square units is larger than that of the light-transmitting square units.
The detector is an area array CCD or an area array CMOS and comprises a plurality of units which are arranged in two dimensions and have a photosensitive function.
The percentage of square cells that transmit light is about 0.25.
The technical scheme provided by the invention can solve the problem of noise sensitivity of the lensless camera based on the URA template based on the specific coding template, thereby improving the signal-to-noise ratio of the reconstructed image.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic diagram of implementing lensless imaging based on a URA template according to the background art of the present invention;
fig. 2 is a schematic diagram of a low-noise lens-free imaging method according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Fig. 2 is a schematic diagram of a low-noise lens-free imaging method according to an embodiment of the present invention. As shown in fig. 2, after the detector is powered on, the light emitted by the target and passing through the encoding template is recorded, and the output pattern is subjected to correlation processing with the encoding pattern to reconstruct an image of the target.
The key part of the embodiment of the invention is a coding template and a detector; the method comprises the following specific steps:
1. the detector can be an area array CCD or an area array CMOS and comprises a plurality of units which are arranged in a two-dimensional mode and have a light sensing function, and the size of an effective area array (the area formed by light sensing units) of the detector is larger than half of the size of the pattern of the coding template.
2. The coding template is a coding pattern etched by utilizing an etching technology after a metal film is plated on a glass substrate, the coding pattern is composed of a plurality of light-transmitting and light-non-transmitting square units with the same size, the distribution of the square units is represented by a matrix generated by the outer product of two pseudo-random vectors composed of 0 and 1, 0 and 1 in the matrix respectively represent that the coding pattern cannot transmit light and can transmit light, wherein the number of the light-non-transmitting square units is larger than that of the light-transmitting square units. Illustratively, the percentage of square cells that are capable of transmitting light is about 0.25.
The coding template is arranged in parallel right in front of the detector, the centers of the coding template and the detector are ensured to be aligned as much as possible, and the size of the square unit and the distance between the coding template and the detector are set according to requirements. The relative positions of the encoding template and the detector are fixed in some way.
In the above scheme of the embodiment of the invention, based on the specific coding template, the problem of the sensitivity of the lensless camera based on the URA template to noise can be solved, so that the signal-to-noise ratio of the reconstructed image is improved.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (3)
1. A low noise lensless imaging method, comprising:
after the detector is electrified, recording light rays emitted by the target and passing through the coding template, and reconstructing an image of the target after the output pattern is subjected to related processing with the coding pattern;
wherein the detector effective area array size is larger than half of the coding template pattern size;
the coding template is a coding pattern etched by utilizing an etching technology after a metal film is plated on a glass substrate, the coding pattern is composed of a plurality of light-transmitting and light-proof square units with the same size, the distribution of the square units is represented by a matrix generated by the outer product of two pseudo-random vectors composed of 0 and 1, 0 and 1 in the matrix respectively represent that the coding pattern cannot transmit light and can transmit light, wherein the number of the light-transmitting square units is larger than that of the light-transmitting square units.
2. A low-noise lens-free imaging method according to claim 1, wherein the detector is an area array CCD or CMOS and includes a plurality of two-dimensionally arranged units having a light sensing function.
3. A low noise lensless imaging method as defined in claim 1, wherein the transparent square cell fraction is 0.25.
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| CN107300827B true CN107300827B (en) | 2020-05-05 |
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| CA3089205A1 (en) | 2018-01-22 | 2019-07-25 | Fnv Ip B.V. | Surveying instrument for and surveying method of surveying reference points |
| CN110277057B (en) * | 2019-06-28 | 2021-01-26 | 京东方科技集团股份有限公司 | Display panel, signal processing method and display device |
| CN112802135B (en) * | 2021-01-15 | 2022-12-02 | 安徽大学 | Ultrathin lens-free separable compression imaging system and calibration and reconstruction method thereof |
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| WO2016123529A1 (en) * | 2015-01-29 | 2016-08-04 | William Marsh Rice University | Lensless imaging system using an image sensor with one or more attenuating layers |
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| GB0602380D0 (en) * | 2006-02-06 | 2006-03-15 | Qinetiq Ltd | Imaging system |
| US8558182B2 (en) * | 2009-10-09 | 2013-10-15 | University Of Rochester | Optical element, device, method, and applications |
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