Boneng Tan

High dynamic range multispectral imaging using liquid crystal tunable filter

Using conventional camera to capture natural scenes with high dynamic range generally results in saturation as well as underexposure, because of their limited dynamic range. And moreover, the image of conventional RGB camera with RGB color filter lacks color accuracy. We present a promising solution - a high dynamic range multispectral camera placing a Liquid Crystal Tunable Filter (LCTF) between lens and gray level imaging sensor. For each bands, gray level images with different exposures are acquired separately and are combined into a multispectral high dynamic range image afterwards. The high dynamic range multispectral image has higher color accuracy and greater dynamic range than the images of the traditional RGB camera.

Fast ARFTIS reconstruction algorithms using CUDA

In order to realize the fast reconstruction processing of all-reflective Fourier Transform Imaging Spectrometer (ARFTIS) data, the authors implement reconstruction algorithms on GPU using Compute Unified Device Architecture (CUDA). We use both CUDA 1DFFT library and customization CUDA parallel kernel to accelerate the spectrum reconstruction processing of ARFTIS. The results show that the CUDA can drive hundreds of processing elements (‘manycore’ processors) of GPU hardware and can enhance the efficiency of spectrum reconstruction processing significantly. Farther, computer with CUDA graphic cards will implement real-time data reconstruction of ARFTIS alone.

Realization of Fourier transform imaging spectrometer based on all-reflective optics

We present our latest research development of the all-reflective Fourier transform imaging spectrometer based on the principle of wavefront-splitting interference. The optical configuration of this system includes a set of Fresnels double mirrors and a number of other reflective telescopes or mirrors. The major advantages of this system includs higher optical throughput, larger spectral bandwidth, and less chromatic aberration as compared with conventinal chromatic-despersion imaging spectrometer . In this paper ,the optical principle and the prototype device of our system are introduced, and the latest experimental results from our prototype device are presented.

Multispectral imaging utilizing LCTF technology for plant disease detection

The aim of this paper is to pave the way for the establishment of analysis of the lights reflected from the leafs surface as an analytical method of plant disease. An imaging LCTF spectrometer that covers a visible light with 400-720 nm wavelength bands has been developed. This paper first outlines the structure of imaging LCTF spectrometer, including their operational principles and construction. Next, various spectral images acquired using the LCTF spectrometer in laboratory environment experiments to measure spectral characteristics of rays reflected from cucumber leaves surfaces that are infected by different germs are analyzed. Then, the results of the experiments conducted using the imaging spectrometer are shown, including the analyzed relative radiance of rays reflected from the plants, and spectral images acquired at various wavelengths. These experimental results demonstrate clearly that rays reflected from plant contaminated by different disease germs have different spectral properties.

High dynamic range color imaging with a camera based on piecewise color characterization

In this paper, we put forward a new method of multiple exposures high dynamic range color imaging with a RGB camera based on a piecewise color characterization model. The construction of the piecewise color characterization model, and the method of images capturing, the color tone mapping and the images combination based on this piecewise color characterization model were introduced. By using an ordinary color camera NikonD70s, we demonstrate our new method can obtain desired high dynamic range images with standard color information.

Study on image registration and spectral construction based on eight-channel imaging spectrometer

An eight-channel imaging spectrometer based on narrowband multi-spectral imaging technology is presented. After acquiring eight images in real time, the spectrometer is used to process images, and finally the color image of object is compounded. Focus is on the methods of image registration and spectral construction. The experiment indicates that point mapping and cubic spline interpolation are effective, and the color composition image is close to the real one. The system has the advantages of high spatial resolution, strong real-time character, hence it can be widely used in the field of moving target recognition.

Evaluating the uniformity of color spaces and performance of color difference formulae

Using small color difference data sets (Macadam ellipses dataset and RIT-DuPont suprathreshold color difference ellipses dataset), and large color difference data sets (Munsell Renovation Data and OSA Uniform Color Scales dataset), the uniformity of several color spaces and performance of color difference formulae based on these color spaces are evaluated. The color spaces used are CIELAB, DIN99d, IPT, and CIECAM02-UCS. It is found that the uniformity of lightness is better than saturation and hue. Overall, for all these color spaces, the uniformity in the blue area is inferior to the other area. The uniformity of CIECAM02-UCS is superior to the other color spaces for the whole color-difference range from small to large. The uniformity of CIELAB and IPT for the large color difference data sets is better than it for the small color difference data sets, but the DIN99d is opposite. Two common performance factors (PF/3 and STRESS) and the statistical F-test are calculated to test the performance of color difference formula. The results show that the performance of color difference formulae based on these four color spaces is consistent with the uniformity of these color spaces.

Parallel cube reconstruction of HSI based on openMP

Hyper Spectral Imager (HSI) on ‘HJ-17rsquo; Chinese satellite is a kind of Fourier Transform imaging spectrometer (FTIS). In order to realize the fast reconstruction processing of HSI data, the authors designed the fast reconstruction algorithms using OpenMP parallel computing. The results show that the framework based on OpenMP can use the multi-core CPU hardware resources competently and can enhance the efficiency of spectrum reconstruction processing significantly. It has already been used on the data processing service of HSI at China Center for Resource Satellite Data and Applications successfully. If this framework is applied to more cores workstation in parallel computing, a single computer to implement real-time data reconstruction of FTIS will be possible.