CN-121999057-A - Full-view field image distortion measuring method, device and storage medium for infrared continuous zoom imaging system

CN121999057ACN 121999057 ACN121999057 ACN 121999057ACN-121999057-A

Abstract

The invention provides a full-view field image distortion measuring method of an infrared continuous variable magnification imaging system, which belongs to the technical field of performance evaluation of continuous variable magnification infrared imaging systems, and comprises the steps of acquiring a round hole target infrared image, calculating a first average distance and a second average distance, further calculating relative distortion, and obtaining full-view field image distortion by screening the relative distortion.

Inventors

Su Lewei
HUANG WEI
MENG HAINENG
YANG TUO
ZHU JIAYI
LU JUNQING
QIN ZHENYU
DONG XUGUANG
ZHOU YI
YUAN YUFEN
LU SHUAIDONG
WANG JIE

Assignees

江苏北方湖光光电有限公司

Dates

Publication Date: 20260508
Application Date: 20260116

Claims (10)

1. The full-view field image distortion measuring method of the infrared continuous zoom imaging system is characterized by comprising the following steps of: Respectively placing round hole targets provided with 4 round holes in 9 acquisition areas in a view field of an infrared continuous zoom imaging system, wherein the 9 acquisition areas are respectively left upper, left middle, left lower, middle upper, center, middle lower, right upper, right middle lower and right lower, and each acquisition area is finely tuned for 10 times to acquire a group of infrared images at the positions of the round hole targets once per fine tuning to obtain an infrared image dataset under the current view field; the method comprises the steps of preprocessing an infrared image data set under a current visual field, calculating the mass center position of a round hole in a round hole target of a sub-pixel level through a gray weighted mass center method; Based on 10 groups of central acquisition area infrared images acquired by placing a round hole target in a central acquisition area, calculating the average value of average distances among centroids of 4 round holes on the round hole target as a first average distance, wherein the average value of average distances among the centroids is the arithmetic average value of the centroid distances among 4 round holes; based on a plurality of groups of peripheral acquisition region infrared images acquired by the round hole target in 8 peripheral acquisition regions, respectively calculating the average value of average distances between the centroids of 4 round holes on the round hole target as second average distances, wherein the second average distances are 8, taking the maximum value of the mode of the difference between each second average distance and the first average distance, and calculating relative distortion according to the maximum value to obtain the relative distortion under the current view; The infrared image data sets are collected under different view fields, preprocessing is carried out on the infrared image data sets collected under different view fields, the relative distortion under different view fields is calculated, and the maximum value of the relative distortion in all view fields is taken, so that the full view field image distortion of the infrared continuous variable magnification imaging system is obtained.
2. The method for measuring the distortion of the full field image of the infrared continuous zoom imaging system according to claim 1, wherein fine adjustment of the target position means small adjustment of the target space position in the same acquisition region, and the target imaging of each group of images is ensured to be positioned in the corresponding acquisition region.
3. The method for measuring the distortion of the full field image of the infrared continuous variable magnification imaging system as set forth in claim 1, wherein the preprocessing is performed by performing a smoothing denoising process on the infrared image in the infrared image dataset through a median filter, so as to maintain the gray level distribution of the infrared image.
4. The full-field image distortion measuring method of the infrared continuous variable magnification imaging system according to claim 1, wherein the specific operation of calculating the centroid position of the round hole of the sub-pixel level by the gray weighted centroid method is that the centroid position of the sub-pixel level is calculated by the gray weighted centroid method by taking the gray value of each acquisition area as a weight according to WeightedCentroid attribute of regionprops function, and the calculation formula of the gray weighted centroid method is as follows: Wherein, the Is the gray value of the pixel point, As the abscissa of the pixel(s), As the ordinate of the pixel, Is the abscissa of the mass center, Is the ordinate of the centroid, To sum all pixels within a single circular aperture area.
5. The method for measuring the distortion of the full-field image of the infrared continuous variable magnification imaging system according to claim 1, wherein the calculation formula of the relative distortion is as follows: Wherein, the In order for the relative distortion to be a function of, As a first average distance, the first average distance, For the second average distance, Is an integer of the number of the times, 。
6. The method for measuring full-field image distortion of an infrared continuous zoom imaging system as set forth in claim 1, wherein 8 of said second average distances are respectively ~ And second average distances corresponding to the 8 peripheral acquisition areas respectively.
7. The method for measuring full field image distortion of an infrared continuously variable magnification imaging system as set forth in claim 1, wherein the infrared image dataset is acquired at the different fields of view, wherein the different fields of view comprise a large field of view, a small field of view, and at least one intermediate variable magnification field of view of the infrared continuously variable magnification imaging system.
8. The method for measuring full field image distortion of an infrared continuous variable magnification imaging system as described in claim 4, wherein said sub-pixel level centroid position, said first average distance, said second average distance, and said relative distortion are achieved by writing a calculation program with MATLAB Is provided.
9. The full-view field image distortion measuring device of the infrared continuous zoom imaging system is characterized by comprising a round hole target provided with 4 round holes, an image acquisition module, a preprocessing module, a centroid calculation module and a distortion calculation module; The image acquisition module is used for acquiring a plurality of groups of infrared images in 9 acquisition areas of the infrared continuous zoom imaging system; The preprocessing module is used for carrying out median filtering denoising on the infrared image; the centroid calculation module is used for calculating the centroid position of the sub-pixel round hole by a gray weighted centroid method; the distortion calculation module is used for calculating a first average distance, a second average distance and relative distortion and outputting a full-view field image distortion maximum value.
10. A computer readable storage medium having stored therein at least one instruction, at least one program, code set, or instruction set loaded and executed by a processor to implement a method of full field image distortion measurement for an infrared continuous variable magnification imaging system according to any one of claims 1 to 8.

Description

Full-view field image distortion measuring method, device and storage medium for infrared continuous zoom imaging system Technical Field The invention belongs to the technical field of performance evaluation of continuous variable magnification infrared imaging systems, and particularly relates to a full-view image distortion measuring method, device and storage medium of an infrared continuous variable magnification imaging system. Background The infrared continuous zoom imaging system realizes continuous imaging under different fields of view by changing the focal length of the optical system. Such systems typically employ mechanically compensated zoom designs that maintain image stabilization through the linkage of lenses such as zoom groups, compensation groups, and the like. However, during continuous zooming, variations in the position of the optical element can introduce varying degrees of distortion. Especially at the short focal end of the large field of view, distortion can be as high as 10%, while the long focal end is typically less than 1%. Since most optical systems are rotationally symmetric about the optical axis. The center of its field of view, i.e. the intersection of the optical axis and the image plane, is the center of symmetry of the system. When the principal ray is incident in the optical axis direction, its propagation path is entirely located on the symmetry axis of the optical system. Under the condition of high symmetry, the refraction effect of the lens on the light rays in different aperture areas is balanced most, so that the deviation of magnification is minimal, the symmetry is destroyed as the angle of view increases and the light rays deviate from the optical axis, the magnification changes, and distortion is generated and aggravated. Mathematically, the distortion value is closely related to the angle of view. Studies have shown that the magnitude of the primary distortion is proportional to the third power of the angle of view. Therefore, in the center region where the angle of view is close to zero, the distortion value approaches zero, and as the angle of view increases, the distortion increases rapidly. Distortion directly affects the geometric accuracy of the image, producing errors in target positioning, observation, and dimensional measurement. Thus, accurate measurement of full field image distortion becomes a key element in ensuring the imaging quality of the system. The heart of measuring the degree of image distortion is to calculate the relative distortion, which is the most common and intuitive indicator. In the prior art, a traditional centroid method and an infrared continuous zoom imaging system distortion measuring machine are generally adopted to calculate relative distortion, the infrared continuous zoom imaging system distortion measuring machine is high in manufacturing cost and belongs to very specialized customized equipment, direct measurement cost is high, when the traditional centroid method is used to calculate the relative distortion, test conditions are strict, the infrared imaging system and a target are required to be accurately aligned, the center of a dot matrix image is ensured to overlap with the imaging center, if errors exist in reference alignment, the distortion calculation can generate deviation, operability is not high in practical project application, a test platform must be kept highly stable for accurately extracting the centroid, any small jitter can cause image jitter, and therefore extraction of centroid coordinates is influenced, and the traditional centroid method needs a large number of coordinate point calculation when testing a large-view field system, is large in workload and complicated, and has great defects in project application with short period and large number. It should be noted that the foregoing is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the foregoing is prior art. Disclosure of Invention The invention mainly aims to provide a full-view field image distortion measuring method, device and storage medium for an infrared continuous zoom imaging system, and aims to solve the technical problems that in the prior art, the relative distortion cost is high, the strict condition that an infrared imaging system is required to be accurately aligned with a target is required, and any small shake can cause image shake, so that the extraction of centroid coordinates is influenced, and the calculation workload of a large number of coordinate points is required to be large and complicated. In order to achieve the above purpose, the invention provides a full-view field image distortion measuring method of an infrared continuous zoom imaging system, which comprises the following steps: Respectively placing round hole targets with 4 round holes in 9 acquisition areas in a visual field of an infrared continuous zoom imaging system, wherein the