Techniques for modifying an image to reduce smear
Techniques to modify an image from a night vision camera so as to reduce smear. An example method comprises receiving at least one image from a night vision camera; modifying the at least one image, based on motion data from a tracker system and a shutter time of night vision camera, to reduce smear in the image; and outputting the modified at least one image.
1 . A method comprising:
receiving at least two sequential images from a night vision camera;
aligning the at least two sequential images based on motion data from a tracker system, and after aligning the at least two sequential images, averaging pixel intensities over the aligned at least two sequential images, to generate an averaged image, wherein the motion data comprises a change in orientation of the night vision camera from which a change in orientation of the at least two sequential images is determined and which is used in the aligning;
applying a filter to the averaged image, to generate a filtered averaged image, wherein one or more filter coefficients of the filter are based on the motion data from the tracker system and a shutter time of the night vision camera; and
outputting the filtered averaged image.
2 . The method according to claim 1 , wherein the at least two sequential images from the camera are from non-consecutive frames from the camera.
3 . The method according to claim 1 , wherein aligning the at least two sequential images based on the motion data from the tracker system comprises calculating a change in rotation of the night vision camera between the at least two sequential images.
4 . The method according to claim 1 , further comprising:
transforming, prior to applying the filter to the averaged image, the averaged image from a first domain to a second domain; and
transforming, prior to outputting the filtered averaged image, the filtered averaged image from the second domain back to the first domain.
5 . The method according to claim 1 , wherein the filter comprises a Weiner filter.
6 . The method according to claim 1 , wherein a frame rate of the night vision camera is higher than a display system frame rate.
7 . The method according to claim 1 , wherein a field of view of the night vision camera is larger than a field of view of a head mounted display or a head up display to display to display filtered averaged image to a user.
8 . The method according to claim 1 , wherein the filter is based on an estimate of smearing, the method comprising estimating, based on the motion data from the tracker system, smearing in at least one of the at least two sequential images, so as to provide the estimate of smearing, wherein the estimate of smearing includes a point spread function, the point spread function being a function which represents a function by which the at least one of the at least two sequential images was smeared.
9 . The method according to claim 8 , wherein the filter is based on an estimated measure of noise in the at least one of the at least two sequential images.
10 . The method according to claim 1 , wherein prior to applying the filter, the method comprising applying a Fourier transform to the averaged image.
11 . The method according to claim 10 , wherein after applying the filter, the method comprises applying an inverse Fourier transform to the filtered averaged image.
12 . The method according to claim 11 , wherein the inverse Fourier transform is an inverse discrete Fourier transform.
13 . The method according to claim 10 , wherein the Fourier transform is a discrete Fourier transform.
14 . The method according to claim 1 , wherein outputting the filtered averaged image comprises displaying the filtered averaged image via a display of a head mounted display or a head up display.
15 . A processing system comprising:
a first circuitry configured to receive at least two sequential images from a night vision camera;
a second circuitry configured to align the at least two sequential images based on motion data from a tracker system, and after aligning the at least two sequential images, the second circuitry is configured to average pixel intensities over the aligned at least two sequential images, to generate an averaged image, and the second circuitry configured to apply a filter to the averaged image, to generate a filtered averaged image, wherein one or more filter coefficients of the filter are based on the motion data from the tracker system and a shutter time of the night vision camera, and wherein the motion data comprises a change in orientation of the night vision camera from which a change in orientation of the at least one image is determined; and
a third circuitry configured to output the filtered averaged image.
16 . The processing system according to claim 15 , wherein the at least two sequential images from the camera are from non-consecutive frames from the camera.
17 . The processing system according to claim 15 , wherein the third circuitry is configured to output the filtered averaged image by causing display of the filtered averaged image via a display of a head mounted display or a head up display, and wherein the processing system is part of head mounted display or a head up display.
18 . A non-transitory machine-readable medium encoded with instructions that when executed by one or more processors causes a process to be carried out, the process comprising:
receiving at least two sequential images from a night vision camera;
aligning the at least two sequential images based on motion data from a tracker system, and after aligning the at least two sequential images, averaging pixel intensities over the aligned at least two sequential images, to generate an averaged image, wherein the motion data comprises a change in orientation of the night vision camera from which a change in orientation of the at least two sequential images is determined and which is used in the aligning;
applying a filter to the averaged image, to generate a filtered averaged image, wherein one or more filter coefficients of the filter are based on the motion data from the tracker system and a shutter time of the night vision camera; and
outputting the filtered averaged image.
19 . A processing system comprising: the one or more processors and the non-transitory machine-readable medium of claim 18 .
20 . The non-transitory machine-readable medium according to claim 18 , wherein outputting the filtered averaged image comprises causing display of the filtered averaged image via a display of a head mounted display or a head up display.