US3882454A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods of differentiating images and of recognizing shapes and characters, utilizing an optical image relay
Assignee: US Philips Corp
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Filing: 1973-02-02
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Granted: 1975-05-06
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Expires: 1993-02-02
Abstract
Abstract The differentiation of an image is achieved by utilizing an optical relay, comprising a plate of an electrooptic material which is brought to a temperature approximating its Curie point, and which as a variable birefringe. The subtraction is effected of images which are projected on the relay, the images corresponding to the initial image but being shifted over a small distance, the birefringe induced by the images being equal, in absolute value and their signs being opposed. Application: recognition of shapes and characters.
Inventors
- 👤 Gerard Marie
- 👤 Jacques Donjon
- 👤 Jean-Pierre Hazan
- 👤 Michel Grenot
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 10:26
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/88
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
162 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting the incrementally shifted image with an effective intensity equal to 1/n times the absolute value of said first projected image, shifting the incrementally shifted image by an additional increment equal to said first increment, projecting said additionally shifted image on said photosensitive layer wiTh an effective intensity equal to the effective intensity of said first incrementally shifted image, and repeatedly shifting and projecting said incrementally shifted images until a total of n incrementally shifted images have been projected, whereby an approximation of a second derivative of said image is obtained.
Claim 2
Independent Claim
162 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting the incrementally shifted image with an effective intensity equal to 1/n times the absolute value of said first projected image, shifting the incrementally shifted image by an additional increment equal to said first increment, projecting said additionally shifted image on said photosensitive layer wiTh an effective intensity equal to the effective intensity of said first incrementally shifted image, and repeatedly shifting and projecting said incrementally shifted images until a total of n incrementally shifted images have been projected, whereby an approximation of a second derivative of said image is obtained.
Claim 3
Dependent Claim
24 words
A method as recited in claim 1, wherein the steps of incrementally shifting said image each comprise the step of incrementally rotating said image.
Claim 4
Dependent Claim
40 words
A method as recited in claim 1, further comprising the steps of resetting the polarity of the applied voltage to the conditions existing during the projection of the first image, and again projecting the first image on said photosensitive layer.
Claim 5
Independent Claim
152 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, first magnifying said image by a magnification slightly larger than 1, projecting said first magnified image on said photosensitive layer with an effective amplitude equal to one-half the effective amplitude of the first projected image, magnifying the first projected image by a magnification which is slightly smaller than 1, and projecting the last mentioned magnified image on the photosensitive layer with an effective amplitude equal to the effective amplitude of the first magnified image, the product of the two magnifications being approximately equal to 1.
Claim 6
Independent Claim
152 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, first magnifying said image by a magnification slightly larger than 1, projecting said first magnified image on said photosensitive layer with an effective amplitude equal to one-half the effective amplitude of the first projected image, magnifying the first projected image by a magnification which is slightly smaller than 1, and projecting the last mentioned magnified image on the photosensitive layer with an effective amplitude equal to the effective amplitude of the first magnified image, the product of the two magnifications being approximately equal to 1.
Claim 7
Independent Claim
134 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, sequentially shifting and projecting n images identical to said first projected image but each shifted by a small vector u1 . . . un, the n vectors having the same absolute value and being regularly angularly shifted with respect to each other over angles equal to 360*/n, each of said n images having an effective amplitude smaller than 1/n times the effective amplitude of said first image.
Claim 8
Independent Claim
134 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, sequentially shifting and projecting n images identical to said first projected image but each shifted by a small vector u1 . . . un, the n vectors having the same absolute value and being regularly angularly shifted with respect to each other over angles equal to 360*/n, each of said n images having an effective amplitude smaller than 1/n times the effective amplitude of said first image.
Claim 9
Independent Claim
160 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting said incrementally shifted image on said photosensitive layer, whereby an approximation of the derivative of said image is obtained forming a hologram of the image information on the optic relay after all the previous steps have been performed, erasing the image information from the optic relay, projecting a different image on the optic relay, reversing the polarity of the applied bias voltage, performing the same steps of incrementally shifting and projecting said different image as were performed with the original image, and projecting the result onto said hologram.
Claim 10
Independent Claim
160 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing the polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting said incrementally shifted image on said photosensitive layer, whereby an approximation of the derivative of said image is obtained forming a hologram of the image information on the optic relay after all the previous steps have been performed, erasing the image information from the optic relay, projecting a different image on the optic relay, reversing the polarity of the applied bias voltage, performing the same steps of incrementally shifting and projecting said different image as were performed with the original image, and projecting the result onto said hologram.
Claim 11
Dependent Claim
20 words
A method as recited in claim 6, wherein said hologram is arranged in the Fourier transform plane of the image.
Claim 12
Independent Claim
149 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing tHe polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting said incrementally shifted image on said photosensitive layer, whereby an approximation of the derivative of said image is obtained projecting the resultant image to a Fourier transform plane, forming a hologram of the projected image in the Fourier transform plane, erasing the image information from the optic relay, projecting a new image on the photosensitive layer of said optic relay, and projecting the new image from the optic relay to the hologram in the Fourier transform plane.
Claim 13
Independent Claim
149 words
A method of optically differentiating images using an optic relay of the type wherein a second image projected on a photosensitive layer is subtracted from a first image projected on the photosensitive layer by reversing tHe polarity of an applied bias voltage during the projection of said second image, the method comprising projecting an image on the photosensitive layer, reversing the polarity of said applied bias voltage, incrementally shifting said image, projecting said incrementally shifted image on said photosensitive layer, whereby an approximation of the derivative of said image is obtained projecting the resultant image to a Fourier transform plane, forming a hologram of the projected image in the Fourier transform plane, erasing the image information from the optic relay, projecting a new image on the photosensitive layer of said optic relay, and projecting the new image from the optic relay to the hologram in the Fourier transform plane.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |