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In this paper, we propose a denoising method for hyperspectral images using a joint bilateral filter. The joint bilateral filter with the fused image of hyperspectral image bands is applied on the noisy image bands. This fused image is a single grayscale image that is obtained by the weighted summation of hyperspectral image bands. It retains the features and details of each hyperspectral image band. Therefore the joint bilateral filter with the fused image is powerful in reducing noise while preserving the characteristics of the individual spectral bands. We evaluated the performance of the proposed noise reduction method on hyperspectral imaging systems, which we developed for visible and near-infrared spectral regions. Experimental results show that the proposed method outperforms the conventional approaches, such as the basic bilateral filter.

In this paper, the improvement of range precision in a laser detection and ranging (LADAR) system by using two Geiger mode avalanche photodiodes (GmAPDs) is described. The LADAR system is implemented by using two GmAPDs with a beam splitter and applying comparative process to their ends. Then, the timing circuit receives the electrical signals only if each GmAPDs generates electrical signals simultaneously. Though this system decreases the energy of a laser-return pulse scattered from the target, it is effective in reducing the range precision. The experimental results showed that the average value of standard deviation of time of flights was improved from 61 mm to 37 mm when the pulse energy is 0.6 μJ. When the time bin width is 0.5 ns, the single-shot precision error of the LADAR system was also improved from 280 mm to 67 mm.

This paper presents an extended bilateral filter with spectral angles and a visualization scheme for hyperspectral image data. The conventional bilateral filter used to be implemented using a position vector and a luminance value at each pixel in the scene. Since hyperspectral image data can provide a spectrum vector that has hundreds of bands at each pixel, we propose an extended bilateral filter using spectral angles. The proposed bilateral filter can be used for extracting and preserving the spectrum edges of the hyperspectral image. A visualization scheme for hyperspectral images exploiting the proposed bilateral filter has been also proposed. When objects that have the similar tristimulus intensity but different spectrums are mixed, they can be separated through the proposed visualization scheme. The resulting images show that the proposed scheme facilitates anomaly detection in the hyperspectral scenes.