Hyper-spectral imaging when observed object is still
A hyperspectral imaging systems includes an imaging sensor, a multispectral filter, and an actuator. The actuator moves the multispectral filter with respect to the imaging sensor to capture a scene with full spectral data. The spectral data of the scene can be stored in a hyperspectral data cube, which can be compressed, processed, stored, and/or sent to a remote location. Each acquired image includes a spatial map of the scene which facilitates pointing, focusing, and data analysis. The spectral measurement parameters can be configured dynamically in order to optimize performance such as spectral resolution, storage capacity, and transmission bandwidth. The system achieves high spectral and spatial resolution, is simple, compact, and lightweight, thereby providing an efficient hyperspectral imaging system.
1. A multispectral imaging apparatus, comprising:
an area imaging device having a plurality of pixel sensors;
a multispectral filter disposed within an optical path of the area imaging device;
an actuator configured to move the multispectral filter with respect to the area imaging device;
a control module configured to:
determine a spatial region of interest of a scene to be captured by the area imaging device;
determine a spectrum of interest of the scene;
determine, based at least in part upon the multispectral filter and the spectrum of interest, a sampling distance that the multispectral filter is to be moved with respect to the area imaging device between sequential exposures taken by the area imaging device; and
direct the area imaging device to take one or more exposures at the sampling distance; and
an imaging module configured to form an image of the scene based at least on the one or more exposures.
2. The apparatus of claim 1 , further comprising a satellite and wherein the area imaging device, the control module, and the imaging module are on-board the satellite.
3. The apparatus of claim 1 , wherein the multispectral filter is a continuously variable optical filter.
4. The apparatus of claim 1 , wherein the multispectral filter is an optical bandpass filter or a notch filter.
5. The apparatus of claim 1 , wherein the imaging module is configured to apply an image stabilizing adjustment to the image to correct for relative motion between the pixel sensors and the spatial region of interest.
6. The apparatus of claim 3 , wherein the image is a hyperspectral image, and the hyperspectral image is stored, processed, and transmitted to a receiving device.
7. The apparatus of claim 1 , wherein the sampling distance is determined such that the spatial region of interest of the scene is captured in the one or more exposures at the spectrum of interest.
8. The apparatus of claim 1 , wherein the imaging module is further configured to create an interpolation curve for each pixel across the one or more exposures.
9. The apparatus of claim 8 , wherein the imaging module is further configured to construct a monochromatic image by evaluating the interpolation curve for each pixel at the spectrum of interest.
10. An imaging apparatus, comprising:
an imaging device having a plurality of pixel sensors;
an optical filter disposed within an optical path of the imaging device, the optical filter having at least a first spectral band and a second spectral band;
an actuator attached to the optical filter and configured to move the optical filter with respect to the plurality of pixel sensors;
one or more processors
a memory; and
programming instructions stored on the memory and executable by the one or more processors to perform acts including:
determining a spatial region of interest of a scene;
determining a spectrum of interest;
activating the actuator to move the optical filter with respect to the plurality of pixel sensors;
determining, based at least in part on a speed of the actuator, a time, during movement of the optical filter, to take at least one exposure of the scene at the spectrum of interest;
directing the imaging device to take the at least one exposure of the scene at the time when the optical filter is positioned with respect to the plurality of pixel sensors such that light reflected from the spatial region of interest passes through the second spectral band of the optical filter, wherein the second spectral band corresponds to the spectrum of interest; and
generating an image of the scene based on the at least one exposure.
11. The imaging apparatus of claim 10 , wherein the optical filter varies in a bandpass along a single direction and the actuator is configured to move the optical filter across the plurality of pixel sensors in the single direction.
12. The imaging apparatus of claim 11 , wherein the optical filter is a continuous variable optical bandpass filter, the plurality of pixel sensors are arranged in an array of rows and columns, and a column of the pixel sensors are associated with a common spectral band of the continuous variable optical bandpass filter for a given position of the actuator.
13. The imaging apparatus of claim 10 , wherein the spectrum of interest includes the first spectral band and the second spectral band, wherein the at least one exposure is a second exposure, wherein the time is a second time, and wherein the programming instructions cause the one or more processors to perform further acts comprising:
directing the imaging device to capture a first exposure at a first time when the optical filter is positioned with respect to the plurality of pixel sensors such that light reflected from the spatial region of interest passes through the first spectral band of the optical filter.
14. The imaging apparatus of claim 13 , wherein generating the image of the scene is based on the first exposure and the second exposure.
15. The imaging apparatus of claim 10 , wherein the programming instructions cause the processors to perform further acts comprising:
segmenting a first exposure to create a first portion of the first exposure having a spectral band of interest,
segmenting a second exposure to create a second portion of the second exposure having the spectral band of interest; and
stitching together the first portion and the second portion to create an image having the spectral band of interest.
16. The imaging apparatus of claim 15 , wherein the image having the spectral band of interest is a first image at a first wavelength and the programming instructions cause the processors to perform further acts comprising creating a second image at a second wavelength and creating a hyperspectral cube containing the first image and the second image.
17. A method of operating a hyperspectral imaging system, the method comprising:
providing an area imaging device having a multispectral optical filter and an actuator for moving the multispectral optical filter with respect to the area imaging device;
determining a sampling distance that the multispectral optical filter is to be moved with respect to the area imaging device between sequential exposures taken by the area imaging device, the sampling distance based at least in part upon the multispectral optical filter and a spectral band of interest;
directing the area imaging device to take a first exposure of a scene;
moving the multispectral optical filter with respect to the area imaging device a distance that is equal to the sampling distance;
directing the area imaging device to take a second exposure of the scene after moving the multispectral optical filter; and
generating an image of the scene based at least on the first exposure and the second exposure.
18. The method of claim 17 , wherein generating the image of the scene comprises:
determining a spectrum of interest;
segmenting the first exposure to create a first image slice having the spectrum of interest;
segmenting the second exposure to create a second image slice having the spectrum of interest; and
stitching together the first image slice and the second image slice to form the image of the scene having the spectrum of interest.
19. The method of claim 18 , further comprising generating a second image of the scene having a second spectrum of interest and creating a multispectral cube that comprises the image of the scene having the spectrum of interest and the second image of the scene having the second spectrum of interest.
20. The method of claim 17 , further comprising:
inputting at least the first exposure and the second exposure as an input to an image analysis algorithm;
creating, based at least in part by executing the image analysis algorithm, a numerical value;
storing the numerical value; and
transmitting the numerical value to a remote location.
21. The method of claim 17 , wherein the imaging system is mounted on a stationary device and the method further comprises compressing the image and transmitting the image to a receiving device.
22. The method of claim 20 , wherein creating the numerical value comprises creating one or more numerical values for each of a plurality of pixels that make up at least a portion of the first exposure or the second exposure, or both.