US3728482A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Focusing
Assignee: Image Analysing Computers Ltd
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Filing: 1970-11-05
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Granted: 1973-04-17
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Expires: 1990-11-05
Abstract
Abstract The invention provides a system for modifying the electrical signal corresponding to the high frequency content of a video signal in accordance with variations in other parameters of the video signal, so as to render the modified signal substantially independent of such variations. Such modification is referred to as normalising the high frequency signal. One system is described for normalising with respect to the number of feature boundaries, another the density changes across the boundaries and another the obliquity of the boundaries to the scanning direction. A further modification allows improvement to the signal to noise ratio of the modified signal.
Inventors
- 👤 J Wren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:25
CPC Classifications
H; H04; H04B; H04B15/00; H04N; H04N5/00; H04N5/14
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
132 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electriCal signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal whose value indicates the number of line scan intersections with feature boundaries of said image and signal modifying means responsive to said first and second electrical signals for modifying the value of said second electrical signal to produce said normalized electrical focus control signal, further including means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 2
Independent Claim
132 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electriCal signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal whose value indicates the number of line scan intersections with feature boundaries of said image and signal modifying means responsive to said first and second electrical signals for modifying the value of said second electrical signal to produce said normalized electrical focus control signal, further including means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 3
Independent Claim
184 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal whose value indicates the number of line scan intersections with feature boundaries of said image and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal wherein said first electrical signal is produced by a means for summing the high frequency content of the video signal over a given time interval, and said means for generating said second electrical signal includes means responsive to said video signal for generating an electrical signal pulse corresponding to each detected feature boundary and means for summing said electrical signal pulses during said time interval to produce said second electrical signal.
Claim 4
Independent Claim
184 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal whose value indicates the number of line scan intersections with feature boundaries of said image and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal wherein said first electrical signal is produced by a means for summing the high frequency content of the video signal over a given time interval, and said means for generating said second electrical signal includes means responsive to said video signal for generating an electrical signal pulse corresponding to each detected feature boundary and means for summing said electrical signal pulses during said time interval to produce said second electrical signal.
Claim 5
Dependent Claim
226 words
An automatic focusing system comprising in combination with a normalising system as set forth in claim 2 means for altering the focus of an image on the photosensitive target of a scanning device producing a scanned electrical video signal corresponding to the image, circuit means for supplying the scanned electrical video signal to the normalising system, means for generating perturbation signals, circuit means for supplying a pertubation signal to the means for altering the focus to adjust the focus by an increment in one direction, means for comparing the output from the said system before and after said perturbation signal is applied and means controlling the production of further perturbation signals in response to said comparison thereby to produce a second perturbation signal producing an increment of focus adjustment in the same direction as the first perturbation signal if the first perturbation signal resulted in an increase in the level of the mormalised signal from the said system and a perturbation signal producing an increment of focus adjustment in the opposite direction to the first perturbation signal if the first perturbation signal resulted in a decrease in the level of the normalised signal from said system, and further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 6
Dependent Claim
51 words
A system as set forth in claim 2 further comprising a variable gain amplifier for amplifying said first electrical signal and circuit means responsive to said second electrical signal controlling the gain of said variable gain amplifier to decrease the gain thereof in response to an increase in the second signal.
Claim 7
Dependent Claim
36 words
A system as set forth in claim 2 further comprising signal integrating circuit means for effecting said signal summation and means to reset the integrating circuit means at the end of each said given time interval.
Claim 8
Independent Claim
216 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electricaL signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal wherein said variable parameter is the number of line scan intersections with feature boundaries and said first electrical signal is produced by a means for summing the high frequency content of the video signal over a given time interval and said second electrical signal is produced by a means for generating an electrical signal pulse corresponding to each detected feature boundary and a means for summing the electrical signal pulses during said time interval.
Claim 9
Independent Claim
216 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electricaL signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal wherein said variable parameter is the number of line scan intersections with feature boundaries and said first electrical signal is produced by a means for summing the high frequency content of the video signal over a given time interval and said second electrical signal is produced by a means for generating an electrical signal pulse corresponding to each detected feature boundary and a means for summing the electrical signal pulses during said time interval.
Claim 10
Dependent Claim
215 words
An automatic focusing system comprising in combination with a normalising system as set forth in claim 6 means for altering the focus of an image on the photosensitive target of a scanning device producing a scanned electrical video signal corresponding to the image, circuit means for supplying the scanned electrical video signal to the normalising system, means for generating perturbation signals, circuit means for supplying a perturbation signal to the means for altering the focus to adjust the focus by an increment in one direction, means for comparing the output from the said system before and after said perturbation signals in response to said comparison thereby to produce a second perturbation signal producing an increment of focus adjustment in the same direction as the first perturbation signal if the first perturbation signal resulted in an increase in the level of the normalised signal from the said system and a perturbation signal producing an increment of focus adjustment in the opposite direction to the first perturbation signal if the first perturbation signal resulted in a decrease in the level of the normalised signal from the said system, and comprising means for gating the signal indicative of the high frequency content of the video signal and presenting the passage thereof except in the region of feature boundaries.
Claim 11
Dependent Claim
51 words
A system as set forth in claim 6 further comprising a variable gain amplifier for amplifying said first electrical signal and circuit means responsive to said second electrical signal controlling the gain of said variable gain amplifier to decrease the gain thereof in response to an increase in the second signal.
Claim 12
Dependent Claim
19 words
A system as set forth in claim 6 further comprising time averaging circuit means for effecting said signal summation.
Claim 13
Dependent Claim
37 words
A system as set forth in claim 6 further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 14
Independent Claim
153 words
A system for producing a normalized electrical focus signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical sIgnal to produce said normalized electrical focus control signal, said variable parameter being the grey level difference at each feature boundary.
Claim 15
Independent Claim
153 words
A system for producing a normalized electrical focus signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical sIgnal to produce said normalized electrical focus control signal, said variable parameter being the grey level difference at each feature boundary.
Claim 16
Dependent Claim
197 words
An automatic focusing system comprising in combination with a normalising system as set forth in claim 11 means for altering the focus of an image on the photosensitive target of a scanning device producing a scanned electrical video signal corresponding to the image, circuit means for supplying the scanned electrical video signal to the normalising system, means for generating perturbation signals, circuit means for supplying a perturbation signal to the means for altering the focus to adjust the focus by an increment in one direction, means for comparing the output from the said system before and after said perturbation signal is applied and means controlling the production of further perturbation signals in response to said comparison thereby to produce a second perturbation signal producing an increment of focus adjustment in the same direction as the first perturbation signal if the first perturbation signal resulted in an increase in the level of the normalised signal from the said system and a perturbation signal producing an increment of focus adjustment in the opposite direction to the first perturbation signal if the first perturbation signal resulted in a decrease in the level of the normalised signal from the said system.
Claim 17
Dependent Claim
39 words
An automatic focusing system as set forth in claim 12 further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 18
Dependent Claim
56 words
A system as set forth in claim 11 further comprising means for generating two electrical signals corresponding to the blackest and whitest image content over a restricted region of the image and means for generating a further signal corresponding to the difference between the said two electrical signals, said further signal constituting said second electrical signal.
Claim 19
Dependent Claim
51 words
A system as set forth in claim 14 further comprising a variable gain amplifier for amplifying the first electrical signal and circuit means responsive to said further electrical signal controlling the gain of said variable gain amplifier to decrease the gain thereof in response to an increase in said further signal.
Claim 20
Dependent Claim
37 words
A system as set forth in claim 11 further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 21
Independent Claim
157 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal, said variable parameter being the obliquity of each boundary to the direction of line scan.
Claim 22
Independent Claim
157 words
A system for producing a normalized electrical focus control signal indicative of the focus of an image comprising means responsive to a scanned electrical video signal of the image to generate a first electrical signal whose value indicates the high frequency content of the video signal, means also responsive to said video signal to generate a second electrical signal in exact time synchronism with said first electrical signal wherein the value of said second electrical signal indicates the value of a variable parameter associated with the feature content of the image which variable parameter affects the high frequency content of the video signal, and signal modifying means responsive to said first and second electrical signals for modifying the value of said first electrical signal in accordance with the value of said second electrical signal to produce said normalized electrical focus control signal, said variable parameter being the obliquity of each boundary to the direction of line scan.
Claim 23
Dependent Claim
174 words
A system as set forth in claim 17 further comprising means for comparing detected video signal from a current line scan with that from the previous line scan, means for generating one electrical signal whose pulse width is proportional to the time displacement of a detected boundary in the previous and current scan lines, means responsive to the said one signal to generate another signal whose pulse height is proportional to the pulse width Of said one signal, means for storing a signal representative of said pulse height, means for delaying the said first electrical signal or the generation thereof by a time period corresponding to a maximum permissible time displacement of a detected boundary between two adjacent scan lines, variable gain amplifier means for amplifying delayed first electrical signal, circuit means for controlling the gain of said variable gain amplifier and means for supplying thereto the stored signal corresponding to the pulse height thereby to increase the gain of the variable gain amplifier in proportion to the pulse height of the stored signal.
Claim 24
Dependent Claim
37 words
A system as set forth in claim 17 further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
Claim 25
Dependent Claim
197 words
An automatic focusing system comprising in combination with a normalising system as set forth in claim 17 means for altering the focus of an image on the photosensitive target of a scanning device producing a scanned electrical video signal corresponding to the image, circuit means for supplying the scanned electrical video signal to the normalising system, means for generating perturbation signals, circuit means for supplying a perturbation signal to the means for altering the focus to adjust the focus by an increment in one direction, means for comparing the output from the said system before and after said perturbation signal is applied and means controlling the production of further perturbation signals in response to said comparison thereby to produce a second perturbation signal producing an increment of focus adjustment in the same direction as the first perturbation signal if the first perturbation signal resulted in an increase in the level of the normalised signal from the said system and a perturbation signal producing an increment of focus adjustment in the opposite direction to the first perturbation signal if the first perturbation signal resulted in a decrease in the level of the normalised signal from the said system.
Claim 26
Dependent Claim
39 words
An automatic focusing system as set forth in claim 20 further comprising means for gating the signal indicative of the high frequency content of the video signal and preventing the passage thereof except in the region of feature boundaries.
References Cited (Backward Citations)
US2134757A
Cited
US2999436A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |