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US4258394A
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US
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Digital circuit for accurately detecting changes in the gray scale of a scanned image
Assignee: Northrop Grumman Corp
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Filing: 1977-08-26
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Granted: 1981-03-24
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Expires: 1997-08-26
Abstract
Abstract A digital circuit for detecting changes in the gray scale of scanned images is disclosed. Each line of video information produced by scanning the image is digitized. Each digital sample is compared to digital samples delayed a predetermined amount to generate a difference signal which is indicative of a change in the gray scale having a component perpendicular to the direction of scan. The digitized samples of the video signal are also stored in a memory having a capacity sufficient to store data representing a plurality of scan lines with a typical memory having a capacity for storing digital information representing eight scan lines. Selected digital samples from the stored data are compared to samples of the line being scanned to detect changes in the gray scale having a component parallel to the direction of scan. These changes in the gray scale are combined to generate a signal indicative of the central portion of the change in the gray scale of the image being scanned to drive a printer to generate a line drawing with the position of the lines corresponding to the central portion of the changes in gray scale of the scanned image.
Inventors
- 👤 Paul G. Kennedy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:15
CPC Classifications
G; G06; G06T; G06T7/00; G06T7/10; G06T7/12; G06T2200/00; G06T2200/28; G06T2207/00; G06T2207/10; G06T2207/10016
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
158 words
A system for scanning an image to detect changes in the gray scale of the image being scanned, comprising: (a) a scanner for scanning said image to produce a plurality of lines of video information, said plurality of lines of video information comprising a video signal representing said image being scanned; (b) delay means for delaying said video signal by a predetermined amount to produce a first delayed video signal; (c) means for comparing the amplitude of said video signal to the amplitude of said first delayed video signal and for generating a plurality of pulses with a pulse being generated each time the absolute value of the difference between these signals exceeds a predetermined value; (d) storage means for storing a predetermined number of said pulses; (e) circuit means for examining the pattern of said stored pulses to generate a signal indicative of the central portion of the change in gray scale represented by said stored pulses.
Claim 2
Independent Claim
158 words
A system for scanning an image to detect changes in the gray scale of the image being scanned, comprising: (a) a scanner for scanning said image to produce a plurality of lines of video information, said plurality of lines of video information comprising a video signal representing said image being scanned; (b) delay means for delaying said video signal by a predetermined amount to produce a first delayed video signal; (c) means for comparing the amplitude of said video signal to the amplitude of said first delayed video signal and for generating a plurality of pulses with a pulse being generated each time the absolute value of the difference between these signals exceeds a predetermined value; (d) storage means for storing a predetermined number of said pulses; (e) circuit means for examining the pattern of said stored pulses to generate a signal indicative of the central portion of the change in gray scale represented by said stored pulses.
Claim 3
Dependent Claim
85 words
A system for scanning an image to detect changes in the gray scale of the image being scanned in accordance with claim 1 wherein said delay means includes means for digitizing said video signal to produce digital numbers and digital storage means for storing a predetermined number of digital numbers, each of said digital numbers being representative of the amplitude of said video signal at a predetermined sample time; and read means for selectively recovering said digital numbers to produce said first delayed video signal.
Claim 4
Dependent Claim
106 words
A system for scanning an image to detect changes in the gray scale of the image being scanned in accordance with claim 2 wherein said means for comparing said video signal to said first delayed video signal comprises an adder for adding said digital numbers representing said video signal to the complement of said digital numbers representing said first delayed video signal and a logic circuit for combining the output signal of said adder to produce a digital number equal to the absolute value of the difference between the digital numbers representing said video signal and the said digital numbers representing said first delayed video signal.
Claim 5
Dependent Claim
39 words
A system for scanning an image to detect changes in the gray scale of the image being scanned in accordance with claim 3 wherein said storage means for storing a predetermined number of said pulses is a shift register.
Claim 6
Dependent Claim
65 words
A system in accordance with claim 4 further including means for selectively recovering said stored digital numbers to generate said first and second delayed video signals and means for comparing said first and second delayed video signals to said video signal to independently detect changes in said gray scale in a direction parallel to scanning and in a direction perpendicular to the direction of scanning.
Claim 7
Dependent Claim
43 words
A system in accordance with claim 5 further including means for producing a first line segment of predetermined length for each detected change in the gray scale in a direction perpendicular to scanning, said line segment comprising a portion of a line drawing.
Claim 8
Dependent Claim
48 words
A system in accordance with claim 6 further including means for producing a second line segment of a predetermined length for each detected change in the gray scale in a direction parallel to the direction of scanning, said first line segment comprising a portion of a line drawing.
Claim 9
Dependent Claim
37 words
A system in accordance with claim 7 wherein said first and said second line segments comprise a line drawing with the line of this drawing corresponding to the detected changes in the gray scale by said image.
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) | 1984-03-23 | 1984-09-22 | 1985-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-23 | 1988-09-22 | 1989-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-23 | 1992-09-22 | 1993-03-24 | $7700.00 | Window Closed / Lapsed |