| 其他摘要 | Multi-wavelength observation is an important method in the study of solarphysics.A lot of solar activities usually occur at different radiation levels and presentdifferent appearances.Only when the observation images of multi-wavelength are regis-tered, can the active phenomena be synthetically analyzed. With the increasing demandfor ?ne information observation in solar physics research,high accuracy registration ofmulti-wavelength images. At present, the multi-wavelength image registration of the sun is mainly based oncross-correlation alignment using the similar feature structure of the image.However,the cross-correlation algorithm obtains the translation between images, but ignoresthe differences in scale and rotation between them.At the same time, in the processof extracting similar features, there are some physical assumptions.For example, it isassumed that the brightening structure observed in multi-wavelength should be one-to-one corresponding in space.These factors result in a alignment accuracy of only1 arcsec-2 arcsec.Because of the complexity of the measured solar images, such aslow contrast, low signal-to-noise ratio, and different spatial resolution, the classi-cal image registration method can not be directly applied.It is necessary to combinesome measurement methods with the corresponding image registration methods toachieve the high accuracy of multi-wavelength image registration.The main work ofthis thesis is to study the sub-angular second high-precision registration method forthe multi-wavelength high-resolution observation images of New Vacuum Solar Tele-scope(NVST).The work of the thesis has obtained important research results in thefollowing aspects:? High accuracy registration of NVST multi-wavelength photospheric imagesbased on the same structure This part mainly focuses on the registration of NVST multi-wavelength photo-spheric images(G-band image and TiO image). Because of the high similarity of the so-lar structure and the close spatial resolution of the images, a registration method basedon ”the combination of regional statistics and feature point matching” is proposed inthis paper. Calculate the correlation offset of the local region of the image, and thenobtain and filter the matching control points(CPs) of the image. The high precisionregistration of image is realized, and the alignment accuracy is about 0.04 arcsec.? High accuracy registration of chromospheric image and photospheric imagebased on off-band scanning image This part mainly aims at the registration between chromospheric image and pho-tospheric image of NVST. The difference of the solar structure in chromosphere andphotosphere is obvious, and there is no obvious similarity between the images. At thesame time, the chromospheric image and photospheric image of NVST have differentspatial resolution. However, chromospheric image observation of NVST can realizewavelength scanning in the range of ±0.4 nm, so this thesis proposes a method of im-age registration with offset observation. The chromospheric observation adopts the”dense scanning” acquisition mode. The SIFT algorithm is used to realize the registra-tion between the far-wing offband image and the photospheric image. Combining withthe alignment between the offband scanning images, the high precision registration be-tween chromospheric image and the photospheric image is realized. Image alignmentaccuracy is about 0.21 arcsec.? Registration of chromospheric image and photospheric image of NVST basedon full-disk solar image This part mainly aims at the registration of chromospheric image and photosphericimage without the help of offband observation. This requires the use of other obser-vation equipment to obtain a full-disk chromospheric image as well as full-disk photo-spheric image. Through the steps of ”the registration of full-disk chromospheric imageand full-disk photospheric image”, ”registration of full-disk photospheric image andNVST photospheric image” and ”registration of full-disk chromospheric image andNVST chromospheric image”, by using the Fourier Merlin algorithm(FM), the regis-tration chromospheric image and photospheric image of NVST is realized. Because thespatial resolution of the full-disk image is much lower than that of the NVST images,the alignment accuracy is low, and about 0.87 arcsec.? High accuracy registration of multi-wavelength solar images based on fieldcalibration by pinhole aperture Different from the above three methods, this part of the work does not dependon the existence of similar features of the solar structure between the images. Weplace a specially designed pinhole array aperture on the front focal plane of the NVSTmulti-wavelength observation system. The pinhole array images are collected in eachobservation channel (wavelength), as a result, the matching feature structure in theimage is generated artificially. Combining the strict synchronous acquisition mode ofeach channel image, the method of feature point matching is used to realize the highprecision registration of multi-wavelength images. The alignment accuracy is about0.031 arcsec.? Alignment of NVST single-wavelength time Series Images This part mainly solves the problem of correlation alignment of single-wavelengthtime series images. The least square method is proposed to estimate the offset of im-age sequences. The alignment accuracy of sequences can reach 0.01 pixels. In order tosolve the problem of ”miss aligned” of edge chromosphere images, histogram equaliza-tion is first used for image enhancement, which improves the accuracy of single framecross correlation and further improves the accuracy of time series alignment. In this thesis, the high precision registration of solar multi-wavelength image withsub-angular second based on different methods is realized. These methods can solvethe differences of rotation, scaling and translation between images at the same time,and the registration accuracy is about 0.03 arcsec-0.2 arcsec. At the same time, theleast square offset is used to realize the alignment of the single-wavelength time seriesimages, which improves the alignment accuracy of the sequence images. It ensure thehigh accuracy registration of the sequence images in each wavelength. |
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