Spatial filter

About: Spatial filter is a research topic. Over the lifetime, 6170 publications have been published within this topic receiving 100451 citations.

Programmable axial apodizing and hyperresolving amplitude filters with a liquid-crystal spatial light modulator.

Abstract: Amplitude-transmitting filters for apodizing and hyperresolving applications can be easily implemented by use of a two-dimensional programmable liquid-crystal spatial light modulator operating in a transmission-only mode. Experimental results are in excellent agreement with theoretical predictions. This approach can permit the analysis of various filter designs and can allow the filters to be changed rapidly to modify the response of an optical system.

Destriping Algorithms Based on Statistics and Spatial Filtering for Visible-to-Thermal Infrared Pushbroom Hyperspectral Imagery

Abstract: Following calibration, hyperspectral images remain affected by spatial dimension nonuniformity, i.e., stripe noise, due to stray light interference, slit contamination, and instrument instability. The full spectrum airborne hyperspectral imager (FAHI) is a Chinese next-generation pushbroom sensor with a spectral range covering the visible near-infrared, shortwave-infrared (SWIR), and thermal infrared regions with spectral sampling intervals of 2.34, 3, and 32 nm, respectively. However, the residual stripe noise remains in FAHI images after relative radiometric correction based on the laboratory calibration, especially in low signal-to-noise ratio bands. To solve this problem, a new technique combining image statistics and spatial filtering algorithms has been developed for FAHI image correction. In this method, image statistics are obtained to calculate the gain and offset of each pixel for image nonuniformity correction. Then, a spatial filter removes the residual stripes. This paper presents the principles of this method along with details of validation experiments and results. To validate the effectiveness of the proposed method, comparison with two destriping methods and quantitative analyses are carried out. Moreover, the method is applied to an SWIR hyperspectral image from the TianGong-1 spacecraft, yielding good results. The experimental results suggest that the proposed method is convenient and practical for improving the relative radiometric accuracy of airborne/spaceborne hyperspectral images.

Method of spatially filtering a digital image using chrominance information

Abstract: A method of processing a color digital image having a luminance channel and one or more chrominance channels to improve the tone scale characteristics of the image, includes the steps of: producing a control signal from the one or more chrominance channels; generating a pedestal signal containing mainly low frequency modulation by filtering the luminance channel with a spatial filter, whereby the operation of the spatial filter is modulated by the control signal; and producing a texture signal by subtracting the pedestal signal from the luminance channel.

Image Deblurring and Aperture Synthesis Using a Posteriori Processing by Fourier-transform Holography

Abstract: Image deblurring and aperture synthesis using a posteriori processing by Fourier transform holographic spatial filtering

Single-mode vertical cavity surface emitting laser by graded-index lens spatial filtering

Abstract: 45 mW of power in a single spatial mode has been obtained from a vertical cavity surface emitting laser (VCSEL) in an external cavity setup, using a graded index (GRIN) lens with a spatial filtering high reflecting aperture deposited on its endface The spatial filter on the GRIN lens endface forces a larger single transverse mode in the VCSEL than is obtained without it A brightness of 51×105 W/cm2 str is demonstrated, which is 91% of the maximum achievable