Large Aperture Static Imaging Spectrometer Research Articles

Lossless Compression of Large Aperture Static Imaging Spectrometer Data

The large-aperture static imaging spectrometer (LASIS) is an interference spectrometer with high device stability, high throughput, a wide spectral range, and a high spectral resolution. One frame image of the original data cube acquired by the LASIS shows the image superimposed with interference fringes, which is distinctly different from traditional hyperspectral images. For compression studies using this new type of data, a lossless compression scheme that combines a novel data rearrange method and the lossless multispectral and hyperspectral image compression standard CCSDS-123 is presented. In the rearrange approach, the LASIS data cube is rearranged such that the interference information overlapped on the image can be separated, and the results are then processed using the CCSDS-123 standard. Then, several experiments are conducted to investigate the performance of the rearrange method and examine the impact of different CCSDS-123 parameter settings for the LASIS. The experimental results indicate that the proposed scheme provides a 32.9% higher ratio than traditional rearrange methods. Moreover, an adequate parameter combination for this compression scheme for LASIS is presented, and it yields a 19.6% improvement over the default settings suggested by the standard.

Corrective method for spectral offset error caused by radial distortion in the large aperture static imaging spectrometer

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed

Decomposition of Interference Hyperspectral Images Based on Split Bregman Iteration

Images acquired by Large Aperture Static Imaging Spectrometer (LASIS) exhibit obvious interference stripes, which are vertical and stationary due to the special imaging principle of interference hyperspectral image (IHI) data. As the special characteristics above will seriously affect the intrinsic structure and sparsity of IHI, decomposition of IHI has drawn considerable attentions of many scientists and lots of efforts have been made. Although some decomposition methods for interference hyperspectral data have been proposed to solve the above problem of interference stripes, too many times of iteration are necessary to get an optimal solution, which will severely affect the efficiency of application. A novel algorithm for decomposition of interference hyperspectral images based on split Bregman iteration is proposed in this paper, compared with other decomposition methods, numerical experiments have proved that the proposed method will be much more efficient and can reduce the times of iteration significantly.

THE RESEARCH OF SPECTRAL RECONSTRUCTION FOR LARGE APERTURE STATIC IMAGING SPECTROMETER

Abstract. Imaging spectrometer obtains or indirectly obtains the spectral information of the ground surface feature while obtaining the target image, which makes the imaging spectroscopy has a prominent advantage in fine characterization of terrain features, and is of great significance for the study of geoscience and other related disciplines. Since the interference data obtained by interferometric imaging spectrometer is intermediate data, which must be reconstructed to achieve the high quality spectral data and finally used by users. The difficulty to restrict the application of interferometric imaging spectroscopy is to reconstruct the spectrum accurately. Based on the original image acquired by Large Aperture Static Imaging Spectrometer as the input, this experiment selected the pixel that is identified as crop by artificial recognition, extract and preprocess the interferogram to recovery the corresponding spectrum of this pixel. The result shows that the restructured spectrum formed a small crest near the wavelength of 0.55 μm with obvious troughs on both sides. The relative reflection intensity of the restructured spectrum rises abruptly at the wavelength around 0.7 μm, forming a steep slope. All these characteristics are similar with the spectral reflection curve of healthy green plants. It can be concluded that the experimental result is consistent with the visual interpretation results, thus validating the effectiveness of the scheme for interferometric imaging spectrum reconstruction proposed in this paper.

Comparative Study of Data Compression Methods for Large Aperture Static Imaging Spectrometer.

Facing the problem of choosing different data source as compressing object results in different compression effect, several techniques are investigated to explore a better data source which can reduce the loss of image and spectral information while getting higher compression ratio in the compression work of the large aperture static imaging spectrometer. In this paper the optical path difference dimension data source of LASIS was proposed after analyzing the characteristic of LASIS and then compared with the LASIS and LAMIS data source in detail. The SWIR data collected with the principle prototype of LASIS were used in our experiment. Firstly, three forms of data sources were extracted after detailedly introducing their data characteristic and extracting methods. Secondly, the mature algorithms in engineering JPEG and JPEG2000 were employed to compress and reconstruct the three forms of data sources respectively. Finally, the compression effect was evaluated in the aspect of image content, interference dimension, spectral dimension and compression ratio respectively, and the original spectral curves of three materials choosing from the field of view and those after reconstruction were extracted next, then the loss of spectral information of these three materials were measured by using the SA (Spectral Angle) and RQE (Relative Quadratic Error) values of the spectral curves to evaluate the compression effect. It is demonstrated that using the optical path difference dimension data as compressing object shows obvious advantages compared with LASIS and LAMIS, which achieves a combination of higher compression ratio, lower mean square error, lower peak signal noise ratio and less information loss that is competitive with the best results from the literature. The results show that the proposed optical path difference dimension data source has good performance in preserving the spatial and spectral information during the compression of LASIS than the other two common forms data sources of LASIS.

大孔径静态干涉成像光谱仪曝光时间控制技术

大孔径静态干涉成像光谱仪曝光时间控制技术

FIVQ algorithm for interference hyper-spectral image compression

Based on the improved vector quantization (IVQ) algorithm [1] which was proposed in 2012, this paper proposes a further improved vector quantization (FIVQ) algorithm for LASIS (Large Aperture Static Imaging Spectrometer) interference hyper-spectral image compression. To get better image quality, IVQ algorithm takes both the mean values and the VQ indices as the encoding rules. Although IVQ algorithm can improve both the bit rate and the image quality, it still can be further improved in order to get much lower bit rate for the LASIS interference pattern with the special optical characteristics based on the pushing and sweeping in LASIS imaging principle. In the proposed algorithm FIVQ, the neighborhood of the encoding blocks of the interference pattern image, which are using the mean value rules, will be checked whether they have the same mean value as the current processing block. Experiments show the proposed algorithm FIVQ can get lower bit rate compared to that of the IVQ algorithm for the LASIS interference hyper-spectral sequences.

An adaptive VQ method used on interferential multi-spectral image lossless compression

In this paper, a high efficient adaptive LBG VQ (vector quantization) method is proposed, which is an improved version of the expansion LBG VQ method [1] (proposed in 2009)and exploits the shortest distance from a point to line segment. Moreover, the proposed method is used on the lossless compression of LASIS (Large Aperture Static Imaging Spectrometer) interferential multi-spectral images. Compared with the expansion LBG VQ method proposed in 2009, the experimental results showed that the adaptive LBG VQ method improved the compression performance obviously. And the experiment also showed that when using these LBG VQ methods above without Dual-Direction Prediction [2], the entropy generated by expansion LBG VQ method [1] sometimes will be larger than that generated by traditional LBG VQ method [3], and when using these LBG VQ methods above after Dual-Direction Prediction [2], CR (compression ratio) generated by expansion LBG VQ method [1] sometimes will be less than that generated by traditional LBG VQ method [3], while the entropy generated by the method proposed in this paper will be much less than that generated by either traditional LBG VQ method [3] or the expansion LBG VQ method [1], and CR generated by the method proposed in this paper will be much larger than that generated by either traditional LBG VQ method [3] or the expansion LBG VQ method [1].

Modeling and simulation of effect of optical distortion on the large aperture static imaging spectrometer

As a new type Fourier transform imaging spectrometry, large aperture static imaging spectrometry (LASIS) has come forth in recent years, which has many advantages such as simple principle, high stability and so on. However, the requirement for the optical system design of LASIS was very harsh. As one of the optical aberrations, optical distortion degrades the data quality acquired by LASIS, consequently limits its applications. According to the analysis of the data acquisition principle of LASIS, the data model with the effect of optical distortion was presented, which could be used for LASIS performance pre-evaluation. Finally, the computer simlulation of the data model was achieved with supposed parameters. The simulation results indicated that the relative error more than 5% was induced in the recovery spectrum, and approximate 8 nm spectral line deviation was occurred at the long wavelength region. The results show that the 4% optical distortion was inapplicable for LASIS although it is acceptant for common optical imaging system.