The invention relates to an imaging method, including reconstructing a final image (IF) from intensity values inputted by a limited selection of photodetectors (2). One out of every two photodetectors is selected along columns (CDET) and rows (LDET). The final image has a resolution that is double t
The invention relates to an imaging method, including reconstructing a final image (IF) from intensity values inputted by a limited selection of photodetectors (2). One out of every two photodetectors is selected along columns (CDET) and rows (LDET). The final image has a resolution that is double that of a picture within the plane of the photodetectors. With identical resolution, the modulation transfer function is improved relative to an image that would be inputted while using all the photodetectors. Additionally, an image-sensing optical system that is used for an imaging method according to the invention can be of reduced size and weight, having constant resolution and constant modulation transfer functions.
대표청구항▼
1. An imaging method for providing a final image composed of intensity values assigned respectively to pixels of a matrix of the final image consisting of adjacent columns and adjacent rows of pixels, the method comprising: carrying an image-capturing instrument on board an aircraft or spacecraft, s
1. An imaging method for providing a final image composed of intensity values assigned respectively to pixels of a matrix of the final image consisting of adjacent columns and adjacent rows of pixels, the method comprising: carrying an image-capturing instrument on board an aircraft or spacecraft, said image-capturing instrument comprising an image-sensing optical system and at least one array of photodetectors which is arranged in a focal plane of the image-sensing optical system, said array of photodetectors consisting of adjacent columns and adjacent rows of photodetectors;using the image-capturing instrument to capture radiation intensity values originating from unit regions of a scene; thenconstructing the final image by assigning certain of the intensity values to the pixels of the final image matrix,wherein:the captured intensity values are restricted to a selection of one photodetector out of two along the columns and along the rows of the array of photodetectors, in a manner that constructs a selection of one photodetector out of four in said array of photodetectors; andthe pixels of the final image matrix to which are assigned the intensity values captured by the selected photodetectors are adjacent to each other in the columns and rows of said final image matrix, andwherein the resolution in the focal plane of the image-sensing optical system which results from the size of each photo detector is two times smaller than the resolution associated with each pixel in the final image. 2. An imaging method for providing a final image composed of intensity values respectively assigned to the pixels of a final image matrix consisting of adjacent columns and adjacent rows of pixels, the method comprising: carrying an image-capturing instrument on board an aircraft or spacecraft, said image-capturing instrument comprising an image-sensing optical system and at least one row of photodetectors which is arranged in a focal plane of the image-sensing optical system, said row of photodetectors consisting of adjacent photodetectors aligned in a longitudinal direction;using the image-capturing instrument to capture radiation intensity values originating from unit regions of a scene, during successive exposures conducted such that a view of the scene is advanced in the focal plane perpendicularly to the longitudinal direction of the row of photodetectors; thenconstructing the final image by assigning certain of the intensity values captured to the pixels of the final image matrix,wherein:the captured intensity values are restricted to a selection of one photodetector out of two along the longitudinal direction in the row of photodetectors, and the exposures are conducted such that the view of the scene is advanced in the focal plane, by twice the width of the photodetectors measured perpendicularly to said longitudinal direction, between two exposures; andthe pixels of the final image matrix to which are assigned the intensity values captured during successive exposures by the selected photodetectors are adjacent to each other in the columns and the rows of said final image matrix, andwherein the resolution in the focal plane of the image-sensing optical system which results from the size of each photo detector is two times smaller than the resolution associated with each pixel in the final image. 3. The method according to claim 2, wherein the image-capturing instrument comprises several rows of photodetectors which are adjacent and parallel to the longitudinal direction in the focal plane, said rows forming at least one array, and wherein the radiation intensity values are captured in a time delay integration capture mode, the intensity values assigned to the pixels of the final image being limited to a selection of one photodetector out of two in each row of the array, and restricted to a sequence of exposing the array and reading the intensity values captured in time delay integration mode every two sequences, the sequences of exposing and reading in time delay integration mode occurring each time the view of the scene is advanced in said focal plane by a distance equal to the individual width of the rows of photodetectors, measured perpendicularly to said longitudinal direction. 4. The method according to claim 1, wherein a focal length of the image-sensing optical system is greater than a focal length producing an identical resolution of the final image if said final image were composed of intensity values captured by adjacent photodetectors in the focal plane, the dimensions of said photodetectors remaining constant. 5. The method according to claim 1, wherein the image-capturing instrument is carried on board an aircraft or a terrestrial satellite and wherein the scene is a portion of the Earth's surface. 6. An imaging system comprising an image-capturing instrument intended to be carried on board an aircraft or spacecraft, said image-capturing instrument comprising: an image-sensing optical system adapted to form an image of a scene in a focal plane;at least one array of photodetectors arranged in the focal plane, said array of photodetectors consisting of adjacent columns and adjacent rows of photodetectors, and each photodetector being adapted to capture a radiation intensity value originating from a unit region of the scene; anda control unit, adapted to select one photodetector out of two along the columns and along the rows of the array of photodetectors, in a manner that constructs a selection of one photodetector out of four in said array of photodetectors, and adapted to command the reading of the intensity values captured by the selected photodetectors after a same exposure,the imaging system additionally comprising an image reconstruction unit adapted to assign the intensity values captured by the selected photodetectors to pixels of an image matrix, said pixels to which are assigned the intensity values captured by the selected photodetectors being adjacent to each other in the columns and rows of the final image matrix, andwherein the resolution in the focal plane of the image-sensing optical system which results from the size of each photo detector is two times smaller than the resolution associated with each pixel in the final image. 7. An imaging system comprising an image-capturing instrument intended to be carried on board an aircraft or spacecraft, said image-capturing instrument comprising: an image-sensing optical system adapted to form an image of a scene in a focal plane;at least one row of photodetectors arranged in the focal plane, said row of photodetectors consisting of adjacent photodetectors aligned in a longitudinal direction, and each photodetector being adapted to capture a radiation intensity value originating from a unit region of the scene; anda control unit adapted to select one photodetector out of two along the longitudinal direction of the row of photodetectors, and adapted to command the reading of the intensity values captured during a same exposure by the selected photodetectors, then during successive exposures conducted when the view of the scene is advanced in the focal plane perpendicularly to the longitudinal direction of the row of photodetectors, by twice the width of said photodetectors measured perpendicularly to said longitudinal direction, between two of the exposures,said imaging system additionally comprising an image reconstruction unit adapted to assign to the pixels of an image matrix said intensity values captured during successive exposures by the selected photodetectors, said pixels to which are assigned said intensity values captured by the selected photodetectors being adjacent to each other in the columns and rows of the final image matrix, andwherein the resolution in the focal plane of the image-sensing optical system which results from the size of each photo detector is two times smaller than the resolution associated with each pixel in the final image. 8. The system according to claim 7, wherein the image-capturing instrument comprises several rows of photodetectors which are adjacent and parallel to the longitudinal direction in the focal plane, said rows being part of an array able to capture radiation intensity values according to a time delay integration capture mode, the control unit being adapted to select one photodetector out of two in each row of the array, and to select those of said intensity values captured in time delay integration mode during a sequence of exposing the array and reading said captured intensity values, doing so every two exposure and reading sequences, said exposure and reading sequences being commanded each time the view of the scene is advanced in said focal plane by a distance equal to the individual width of the rows of photodetectors, measured perpendicularly to said longitudinal direction. 9. The system according to claim 7, wherein a focal length of the image-sensing optical system is greater than a focal length producing the same resolution of the final image if said final image were composed of intensity values captured by adjacent photodetectors in the focal plane with the size of said photodetectors remaining constant. 10. The imaging method according to claim 1, wherein intensity values which have been captured by those of the photodetectors which are not selected are left unread. 11. The imaging method according to claim 2, wherein intensity values which have been captured by those of the photodetectors which are not selected are left unread. 12. The system according to claim 6, wherein intensity values which have been captured by those of the photodetectors which are not selected are left unread. 13. The system according to claim 7, wherein intensity values which have been captured by those of the photodetectors which are not selected are left unread.
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이 특허에 인용된 특허 (2)
Lareau Andre G. ; Beran Stephen R. ; James Brian ; Quinn James P. ; Lund John, Autonomous electro-optical framing camera system with constant ground resolution, unmanned airborne vehicle therefor, and methods of use.
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