CN105095896A - Image distortion correction method based on look-up table - Google Patents
Image distortion correction method based on look-up table Download PDFInfo
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Abstract
The invention discloses an image distortion correction method based on a look-up table, and the method comprises the steps: generating the look-up table according to selected reference points in plane grids; enabling a plurality of pixels to be mapped at the same position according to the look-up table; and calculating a mapping proportion of each row according to the look-up table. Moreover, the method can carry out image collection while carrying out image correction. Through the above mode, the method can meet the requirements of target images with different resolution, saves the time in image collection and correction, and relaxes the restriction on the length and width of an image.
Description
Technical field
The present invention relates to algorithm for recognizing fingerprint field, particularly relate to a kind of image distortion correction method based on look-up table.
Background technology
China utilizes fingerprint very long to identify the history of identity, and along with Chinese scholars deepening continuously to fingerprint recognition system research, fingerprint identification technology reaches its maturity, the main aspect of fingerprint Recognition comprises: fingerprint image preprocessing, fingerprint classification, fingerprint feature point extract and fingerprint matching, wherein the pretreatment stage of most importantly image.At present, in space flight and aeroplane photography, medical treatment and various high precision measuring instrument, for obtaining more image informations about object scene, normal employing Large visual angle short-focus lens.Optical distortion to a certain degree is generally all there is in this kind of camera lens in imaging process, the size and shape of image is made to there occurs some change, the Quality Down of image, bring error to graphical analysis below and image measurement, even cause erroneous judgement, therefore must the piecture geometry fault that Large visual angle short focus camera lens causes be corrected.
The image rectification algorithm generally applied now be first entire image collection has been completed after, then it to be corrected, and all restricted to the length of corrected image, width, so people need the correcting algorithm more met the demands.
Summary of the invention
The technical matters that the present invention mainly solves is to provide a kind of image distortion correction method based on look-up table, has the advantages such as reliability is high, efficiency is high, calibration result is good, simultaneously algorithm for recognizing fingerprint application and universal on have market outlook widely.
For solving the problems of the technologies described above, the technical scheme that the present invention adopts is:
There is provided a kind of image distortion correction method based on look-up table, its step comprises:
(1) obtain distortion figure, greyscale transformation is carried out to distortion figure; Then threshold method is utilized to carry out binary conversion treatment; Then, to the refinement of mesh lines list pixel, obtain plane grid image, and utilize plane grid to split distortion figure according to resolution;
(2) according to plane grid, the image information of distortion figure is gathered line by line;
(3) often adopted a line image, found out the symcenter of every a line image, being converted to the address space relation of every a line image with symcenter is the spatial relationship of initial point;
(4) spatial alternation: to the pixel rearrangement on every a line image to recover former spatial relationship, namely utilize address mapping relation to generate correction chart, concrete steps comprise:
(4.1) several reference point chosen in plane grid, and utilize the information of these reference point to generate look-up table;
(4.2) calculate the mapping ratio of every a line image according to look-up table, and according to the resolution of distortion figure, utilize mapping ratio to map the point on the edge of every a line image, the corresponding mapping point obtained forms the pixel on monomer correction chart;
(5) gray scale difference value: give corresponding gray-scale value to recover the gray-scale value of the original position of respective pixel to the pixel after spatial alternation according to look-up table, obtain gray-scale map;
(6) according to plane grid, gather the image information of next line distortion figure, repeat step (3)-(4), until gather and correct whole distortion figure;
(7) obtain the gray-scale map of the correspondence of every a line image of distortion figure, all gray-scale maps are synthesized, generate correction chart.
In a preferred embodiment of the present invention, adopt the method that neighbour is down-sampled, realize laterally and longitudinal linear narrowing.
In a preferred embodiment of the present invention, the quantity of described reference point is more than or equal to 16.
In a preferred embodiment of the present invention, in step (1), the grey scale pixel value that grid bianry image belongs to grid network is 255, and remaining grey scale pixel value is 0.
The invention has the beneficial effects as follows: the target image that can meet different resolution, and save and gather image and the time that it is corrected, and relax the restriction of length to image, width.
Embodiment
Be clearly and completely described to the technical scheme in the embodiment of the present invention below, obviously, described embodiment is only a part of embodiment of the present invention, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making other embodiments all obtained under creative work prerequisite, belong to the scope of protection of the invention.
The embodiment of the present invention comprises:
Based on an image distortion correction method for look-up table, its step comprises:
(1) obtain distortion figure, greyscale transformation is carried out to distortion figure; Then utilize threshold method to carry out binary conversion treatment, wherein, the grey scale pixel value that grid bianry image belongs to grid network is 255, and remaining grey scale pixel value is 0; Then, to the refinement of mesh lines list pixel, obtain plane grid image, and utilize plane grid to split distortion figure according to resolution; Adopt the method that neighbour is down-sampled, realize laterally and longitudinal linear narrowing;
(2) according to plane grid, the image information of distortion figure is gathered line by line;
(3) often adopted a line image, found out the symcenter of every a line image, being converted to the address space relation of every a line image with symcenter is the spatial relationship of initial point;
(4) spatial alternation: the geometric transform method of image is by some known reference point, the i.e. pixel of the position that some pixel of width undistorted image is corresponding with fault image, set up the mapping relations between coordinate, obtain unknown parameter in mapping relations, then according to this funtcional relationship, each pixel coordinate in image is corrected, to the pixel rearrangement on every a line image to recover former spatial relationship, namely utilize address mapping relation to generate correction chart, concrete steps comprise:
(4.1) several reference point chosen in plane grid, 16 that such as choose, and utilize the information of these reference point to generate look-up table;
(4.2) calculate the mapping ratio of every a line image according to look-up table, and according to the resolution of distortion figure, utilize mapping ratio to map the point on the edge of every a line image, the corresponding mapping point obtained forms the pixel on monomer correction chart;
(5) gray scale difference value: give corresponding gray-scale value to recover the gray-scale value of the original position of respective pixel to the pixel after spatial alternation according to look-up table, obtain gray-scale map;
(6) according to plane grid, gather the image information of next line distortion figure, repeat step (3)-(4), until gather and correct whole distortion figure;
(7) obtain the gray-scale map of the correspondence of every a line image of distortion figure, all gray-scale maps are synthesized, generate correction chart.
The distortion of image is divided into two kinds: lateral aberration and longitudinal distortion.Adopt the method that neighbour is down-sampled, realize laterally and longitudinal linear narrowing; The geometric transform method of image is by some known reference point, the i.e. pixel of the position that some pixel of width undistorted image is corresponding with fault image, set up the mapping relations between coordinate, obtain unknown parameter in mapping relations, then according to this funtcional relationship, each pixel coordinate in image is corrected.The present invention generates look-up table data [i] according to 16 reference point selected in plane grid, then according to this look-up table by multiple spot pixel-map to same position, often capable mapping ratio calculates according to look-up table data [i], and can gather image, while carry out the correction of image in limit.
The method gathers by limit the method that distortion correction is carried out on image limit, corrects, save the time, can input the target image met the demands according to the resolution of required image the trapezoidal distortion that gathered image occurs.
The beneficial effect of a kind of image distortion correction method based on look-up table of the present invention is: the target image that can meet different resolution, and saves and gather image and the time corrected it, and relaxes the restriction of length to image, width.
The foregoing is only embodiments of the invention; not thereby the scope of the claims of the present invention is limited; every utilize description of the present invention to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical field, be all in like manner included in scope of patent protection of the present invention.
Claims (4)
1., based on an image distortion correction method for look-up table, it is characterized in that, step comprises:
(1) obtain distortion figure, greyscale transformation is carried out to distortion figure; Then threshold method is utilized to carry out binary conversion treatment; Then, to the refinement of mesh lines list pixel, obtain plane grid image, and utilize plane grid to split distortion figure according to resolution;
(2) according to plane grid, the image information of distortion figure is gathered line by line;
(3) often adopted a line image, found out the symcenter of every a line image, being converted to the address space relation of every a line image with symcenter is the spatial relationship of initial point;
(4) spatial alternation: to the pixel rearrangement on every a line image to recover former spatial relationship, namely utilize address mapping relation to generate correction chart, concrete steps comprise:
(4.1) several reference point chosen in plane grid, and utilize the information of these reference point to generate look-up table;
(4.2) calculate the mapping ratio of every a line image according to look-up table, and according to the resolution of distortion figure, utilize mapping ratio to map the point on the edge of every a line image, the corresponding mapping point obtained forms the pixel on monomer correction chart;
(5) gray scale difference value: give corresponding gray-scale value to recover the gray-scale value of the original position of respective pixel to the pixel after spatial alternation according to look-up table, obtain gray-scale map;
(6) according to plane grid, gather the image information of next line distortion figure, repeat step (3)-(4), until gather and correct whole distortion figure;
(7) obtain the gray-scale map of the correspondence of every a line image of distortion figure, all gray-scale maps are synthesized, generate correction chart.
2. a kind of image distortion correction method based on look-up table according to claim 1, is characterized in that, adopts the method that neighbour is down-sampled, realizes laterally and longitudinal linear narrowing.
3. a kind of image distortion correction method based on look-up table according to claim 1, it is characterized in that, the quantity of described reference point is more than or equal to 16.
4. a kind of image distortion correction method based on look-up table according to claim 1, is characterized in that, in step (1), the grey scale pixel value that grid bianry image belongs to grid network is 255, and remaining grey scale pixel value is 0.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105956530A (en) * | 2016-04-25 | 2016-09-21 | 中科院微电子研究所昆山分所 | Image correction method and image correction device |
| CN105959598A (en) * | 2016-05-30 | 2016-09-21 | 凌云光技术集团有限责任公司 | Camera multichannel balance look-up table calibration method, multichannel balance method and system |
| CN106022058A (en) * | 2016-05-27 | 2016-10-12 | 广东欧珀移动通信有限公司 | Fingerprint unlocking method and terminal |
| CN106767433A (en) * | 2016-12-19 | 2017-05-31 | 北京市计算中心 | A kind of method and system for measuring foot sizing |
| CN108230263A (en) * | 2017-12-11 | 2018-06-29 | 中国航空工业集团公司洛阳电光设备研究所 | A kind of image distortion correction device and method of high safety grade |
| CN109087253A (en) * | 2017-06-13 | 2018-12-25 | 杭州海康威视数字技术股份有限公司 | A kind of method for correcting image and device |
| CN109472760A (en) * | 2019-02-01 | 2019-03-15 | 深兰人工智能芯片研究院（江苏）有限公司 | A kind of method, apparatus of correcting distorted image |
| CN111598060A (en) * | 2019-12-11 | 2020-08-28 | 神盾股份有限公司 | Fingerprint sensing system and method of use thereof |
| CN111601100A (en) * | 2020-03-27 | 2020-08-28 | 惠州市德赛西威汽车电子股份有限公司 | Method and device for calculating TV distortion |
| CN113239918A (en) * | 2021-07-13 | 2021-08-10 | 北京金博星指纹识别科技有限公司 | Image resolution normalization processing method and device |
| US11270416B2 (en) | 2019-12-27 | 2022-03-08 | Nxp Usa, Inc. | System and method of using optimized descriptor coding for geometric correction to reduce memory transfer bandwidth overhead |
| US11443411B2 (en) | 2020-07-08 | 2022-09-13 | Nxp Usa, Inc. | Method and system for image distortion correction using quarter and tangential lookup tables |
| US11605228B2 (en) | 2020-06-26 | 2023-03-14 | Nxp Usa, Inc. | System and method for sensor fusion system having distributed convolutional neural network |
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Cited By (18)
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| CN105956530A (en) * | 2016-04-25 | 2016-09-21 | 中科院微电子研究所昆山分所 | Image correction method and image correction device |
| CN106022058A (en) * | 2016-05-27 | 2016-10-12 | 广东欧珀移动通信有限公司 | Fingerprint unlocking method and terminal |
| CN105959598A (en) * | 2016-05-30 | 2016-09-21 | 凌云光技术集团有限责任公司 | Camera multichannel balance look-up table calibration method, multichannel balance method and system |
| CN105959598B (en) * | 2016-05-30 | 2018-11-13 | 凌云光技术集团有限责任公司 | Camera multichannel balances look-up table scaling method, multichannel balance method and system |
| CN106767433B (en) * | 2016-12-19 | 2019-08-27 | 北京市计算中心 | A kind of method and system measuring foot sizing |
| CN106767433A (en) * | 2016-12-19 | 2017-05-31 | 北京市计算中心 | A kind of method and system for measuring foot sizing |
| CN109087253A (en) * | 2017-06-13 | 2018-12-25 | 杭州海康威视数字技术股份有限公司 | A kind of method for correcting image and device |
| CN109087253B (en) * | 2017-06-13 | 2020-12-25 | 杭州海康威视数字技术股份有限公司 | Image correction method and device |
| CN108230263A (en) * | 2017-12-11 | 2018-06-29 | 中国航空工业集团公司洛阳电光设备研究所 | A kind of image distortion correction device and method of high safety grade |
| CN108230263B (en) * | 2017-12-11 | 2021-11-23 | 中国航空工业集团公司洛阳电光设备研究所 | High-security-level image distortion correction device and method |
| CN109472760B (en) * | 2019-02-01 | 2019-05-21 | 深兰人工智能芯片研究院（江苏）有限公司 | A kind of method, apparatus of correcting distorted image |
| CN109472760A (en) * | 2019-02-01 | 2019-03-15 | 深兰人工智能芯片研究院（江苏）有限公司 | A kind of method, apparatus of correcting distorted image |
| CN111598060A (en) * | 2019-12-11 | 2020-08-28 | 神盾股份有限公司 | Fingerprint sensing system and method of use thereof |
| US11270416B2 (en) | 2019-12-27 | 2022-03-08 | Nxp Usa, Inc. | System and method of using optimized descriptor coding for geometric correction to reduce memory transfer bandwidth overhead |
| CN111601100A (en) * | 2020-03-27 | 2020-08-28 | 惠州市德赛西威汽车电子股份有限公司 | Method and device for calculating TV distortion |
| US11605228B2 (en) | 2020-06-26 | 2023-03-14 | Nxp Usa, Inc. | System and method for sensor fusion system having distributed convolutional neural network |
| US11443411B2 (en) | 2020-07-08 | 2022-09-13 | Nxp Usa, Inc. | Method and system for image distortion correction using quarter and tangential lookup tables |
| CN113239918A (en) * | 2021-07-13 | 2021-08-10 | 北京金博星指纹识别科技有限公司 | Image resolution normalization processing method and device |
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