Computational methods and electronic camera apparatus for determining distance of objects, rapid autofocusing, and obtaining improved focus images

Claim 1

A method of determining the distance of a surface patch of an object from a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (l) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a signal mathematical relationship corresponding to each member of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the signal corresponding mathematical relationship provided in step (l) to obtain a set of equations; and n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system.

Claim 2

A method of determining the distance of a surface patch of an object from a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (l) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a signal mathematical relationship corresponding to each member of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the signal corresponding mathematical relationship provided in step (l) to obtain a set of equations; and n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system.

Claim 9

A method of determining the distance of a surface patch of an object from a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set o Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) comparing the set of ratio values resulting from step (k) to a look-up table in said image processor, said look-up table having stored ratio values corresponding to distances from said camera system, and m) determining said distance of said surface patch from said camera system by the selection of that distance which corresponds most closely to the ratio values from step (k).

Claim 10

A method of determining the distance of a surface patch of an object from a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set o Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) comparing the set of ratio values resulting from step (k) to a look-up table in said image processor, said look-up table having stored ratio values corresponding to distances from said camera system, and m) determining said distance of said surface patch from said camera system by the selection of that distance which corresponds most closely to the ratio values from step (k).

Claim 13

A method for focusing a surface patch of an object on an image detector of a camera system having an aperture through which light enters, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a single mathematical relationship corresponding to each number of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the single corresponding mathematical relationship provided in step (l) to obtain a set of equations; n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system; o) based on the distance determined in step (n), determining the camera parameters corresponding to a focused image of said surface patch; and p) adjusting said camera parameters to the values determined in step (o).

Claim 14

A method for focusing a surface patch of an object on an image detector of a camera system having an aperture through which light enters, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a single mathematical relationship corresponding to each number of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the single corresponding mathematical relationship provided in step (l) to obtain a set of equations; n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system; o) based on the distance determined in step (n), determining the camera parameters corresponding to a focused image of said surface patch; and p) adjusting said camera parameters to the values determined in step (o).

Claim 17

A method for focusing a surface patch of an object on an image detector of a camera system having an aperture through which light enters, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) comparing the set of ratio values resulting from step (k) to a look-up table in said image processor, said look-up table having stored ratio values corresponding to distance from said camera system; m) determining said distance of said surface patch from said camera system by the selection of that distance which corresponds most closely to the ratio values from step (k); n) based on said distance determined in step (m), determining camera parameters corresponding to a focused image of said surface patch; and p) adjusting said camera parameters to the values determined in step (n).

Claim 18

A method for focusing a surface patch of an object on an image detector of a camera system having an aperture through which light enters, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete frequencies; k) dividing said first set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) comparing the set of ratio values resulting from step (k) to a look-up table in said image processor, said look-up table having stored ratio values corresponding to distance from said camera system; m) determining said distance of said surface patch from said camera system by the selection of that distance which corresponds most closely to the ratio values from step (k); n) based on said distance determined in step (m), determining camera parameters corresponding to a focused image of said surface patch; and p) adjusting said camera parameters to the values determined in step (n).

Claim 21

A method for obtaining an improved focus image of a surface patch of an object from its blurred image in a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; `k) dividing said firs set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a single mathematical relationship corresponding to each member of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the single corresponding mathematical relationship provided in step (l) to obtain a set of equations; n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system; o) based on the distance of said surface patch calculated in step (n), determining the optical transfer function of said first image formed in step (b); p) determining the Fourier transform of said first image; q) dividing said Fourier transform resulting from step (p) by said optical transfer function resulting from step (o); and r) computing the inverse Fourier transform of the result from step (q), whereby said improved focus image is determined from its blurred image.

Claim 22

A method for obtaining an improved focus image of a surface patch of an object from its blurred image in a camera system having an aperture through which light enters, an image detector, an image forming optical system having first and second principal planes and a focal length, said second principal plane arranged closer to said image detector than said first principal plane, a light filter, a camera controller, and an image processor operatively connected to said image detector and to said camera controller, said method comprising: a) setting said camera to a first set of camera parameters including at least one of (i) distance (s) between said second principal plane and said image detector, (ii) diameter (D) of said camera aperture, (iii) focal length (f) of said camera system, and (iv) spectral characteristic (λ) of light transmitted by said light filter; b) forming a first image of said surface patch on said image detector; c) recording said first image in said image processor as a first digital image; d) preprocessing said first digital image to provide a first normalized image which is related to the point spread function of said camera system by a convolution operation; e) calculating a first set of Fourier coefficients of said first normalized image at a set of discrete spatial frequencies; f) changing at least one of said camera parameters; g) forming a second image of said surface patch on said image detector; h) recording said second image in said image processor as a second digital image; i) preprocessing said second digital image to provide a second normalized image which is related to the point spread function of said camera by a convolution operation; j) calculating a second set of Fourier coefficients of said second normalized image at said set of discrete spatial frequencies; `k) dividing said firs set of Fourier coefficients by said second set of Fourier coefficients to provide a set of ratio values; l) providing a single mathematical relationship corresponding to each member of said set of ratios, said mathematical relationship provided without any intermediate parameter and representing the ratio of the optical transfer function of said first normalized image to the optical transfer function of said second normalized image, each said mathematical relationship dependent only on said camera parameters and having one unknown equal to said distance of said surface patch from said camera system; m) substituting each ratio value resulting from step (k) in the single corresponding mathematical relationship provided in step (l) to obtain a set of equations; n) solving said set of equations resulting from step (m) to determine said distance of said surface patch from said camera system; o) based on the distance of said surface patch calculated in step (n), determining the optical transfer function of said first image formed in step (b); p) determining the Fourier transform of said first image; q) dividing said Fourier transform resulting from step (p) by said optical transfer function resulting from step (o); and r) computing the inverse Fourier transform of the result from step (q), whereby said improved focus image is determined from its blurred image.

Claim 24

An apparatus for determining the distance between a surface patch of an object and a camera system comprising: a) a camera system including an image detector, a camera aperture, an image forming optical system having first and second principal plane, a light filter and a focal length, said second principal plane arranged closer to said image detector than said first principal plane; b) a camera controller operatively connected to said camera system for movement thereof to change one or more of the following camera parameters, (i) the distance between said principal plane and said image detector, (ii) the diameter of said camera aperture, and (iii) said focal length of said image forming optical system; ) an image processor operatively connected to said image detector and to said camera controller for receipt of signals from said image detector, the image processor varying said camera parameters by means of said camera controller, wherein said image processor includes: (i) means for converting the image detector signal to digital data and normalizing the resulting digital image for further image processing; (ii) means for Fourier transforming signals, and (iii) means for dividing Fourier coefficients to provide a set of Fourier coefficient ratio values corresponding to signals from a first and a second image; and d) means for substituting Fourier coefficient ratio values gathered from said first and second images into a mathematical relationship involving the camera parameters, the distance of said surface patch and the optical transfer function of said camera system, the means for substituting Fourier coefficient ratio values also solving the resulting relationships to provide the distance of said surface patch from said camera system.

Claim 25

An apparatus for determining the distance between a surface patch of an object and a camera system comprising: a) a camera system including an image detector, a camera aperture, an image forming optical system having first and second principal plane, a light filter and a focal length, said second principal plane arranged closer to said image detector than said first principal plane; b) a camera controller operatively connected to said camera system for movement thereof to change one or more of the following camera parameters, (i) the distance between said principal plane and said image detector, (ii) the diameter of said camera aperture, and (iii) said focal length of said image forming optical system; ) an image processor operatively connected to said image detector and to said camera controller for receipt of signals from said image detector, the image processor varying said camera parameters by means of said camera controller, wherein said image processor includes: (i) means for converting the image detector signal to digital data and normalizing the resulting digital image for further image processing; (ii) means for Fourier transforming signals, and (iii) means for dividing Fourier coefficients to provide a set of Fourier coefficient ratio values corresponding to signals from a first and a second image; and d) means for substituting Fourier coefficient ratio values gathered from said first and second images into a mathematical relationship involving the camera parameters, the distance of said surface patch and the optical transfer function of said camera system, the means for substituting Fourier coefficient ratio values also solving the resulting relationships to provide the distance of said surface patch from said camera system.

Claim 27

An apparatus for determining the distance between a surface patch of an object and a camera system comprising: a) a camera system including an image detector, a camera aperture, an image forming optical system having first and second principal planes, a light filter and a focal length, said second principal plane arranged closer to said image detector than said first principal plane; b) a camera controller operatively connected to said camera system for movement thereof to change one or more of the following camera parameters, (i) the distance between said second principal plane and said image detector, (ii) the diameter of said camera aperture, and (iii) the focal length of said image forming optical system; c) an image processor operatively connected to said image detector and to said camera controller for receipt of signals from said image detector, the image processor varying said camera parameters by means of said camera controller, wherein said image processor includes: (i) means for converting the image detector signal to digital data and normalizing the resulting digital image for further image processing, (ii) means for Fourier transforming signals, and (iii) means for dividing Fourier coefficients to provide a set of Fourier coefficient ratio values corresponding to signals from a first and a second image, d) a look-up table computed from the optical transfer function of said camera system, and e) correlation means to determine distances by comparing said set of Fourier coefficient ratio values with values stored in said look-up table.

Claim 28

An apparatus for determining the distance between a surface patch of an object and a camera system comprising: a) a camera system including an image detector, a camera aperture, an image forming optical system having first and second principal planes, a light filter and a focal length, said second principal plane arranged closer to said image detector than said first principal plane; b) a camera controller operatively connected to said camera system for movement thereof to change one or more of the following camera parameters, (i) the distance between said second principal plane and said image detector, (ii) the diameter of said camera aperture, and (iii) the focal length of said image forming optical system; c) an image processor operatively connected to said image detector and to said camera controller for receipt of signals from said image detector, the image processor varying said camera parameters by means of said camera controller, wherein said image processor includes: (i) means for converting the image detector signal to digital data and normalizing the resulting digital image for further image processing, (ii) means for Fourier transforming signals, and (iii) means for dividing Fourier coefficients to provide a set of Fourier coefficient ratio values corresponding to signals from a first and a second image, d) a look-up table computed from the optical transfer function of said camera system, and e) correlation means to determine distances by comparing said set of Fourier coefficient ratio values with values stored in said look-up table.