US3737854A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of classifying characters wherein the effects of variations in contrast between a presented character and its background and variations in background brightness are reduced, and the apparatus therefor
Assignee: Individual
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Filing: 1971-09-08
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Granted: 1973-06-05
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Expires: 1991-09-08
Abstract
Abstract A method of reducing the effects upon character classification attributed to variations in the contrast between a presented character and its background and to variations in background brightness, and the apparatus therefor, are disclosed in accordance with the teachings of the present invention. A presented character is partitioned into a plurality of raster areas and a voltage representing the light intensity of each raster area is produced. A reference voltage proportional to the light intensity of a background area is also produced and difference voltages corresponding to the difference between the reference voltage and each raster area voltage are generated. The difference voltages together with the reference voltage are combined in resistor networks representing predetermined classes of characters to produce output voltages. Each output voltage is compared to a comparison voltage to determine which output voltages lie within certain predetermined limits. The presented character corresponds to the one predetermined class of characters represented by those resistor networks that produce such proper output voltages.
Inventors
- 👤 A Klemt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:30
CPC Classifications
G; G06; G06V; G06V10/00; G06V10/20; G06V10/28; G06V10/70; G06V10/74; G06V10/75
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
244 words
In a character classifying process wherein a presented character is partitioned into a plurality of raster areas, voltages representative of the light intensity of said raster areas are combined in resistor networks representing predetermined classes of characters to produce output voltages and each of said voltages is compared to a comparison voltage to determine which of said predetermined classes said presented character corresponds, an improved method for reducing the influence of variations in contrast between the presented character and its background and variations in background brightness on the character classifying process, comprising the steps of: generating a reference voltage representing the light intensity of a discrete background area that is not provided with any portion of said presented character; producing a plurality of difference voltages, each of said difference voltages being proportional to the difference between said reference voltage and a voltage representative of the light intensity of a corresponding raster area, whereby a difference voltage obtains a minimal value if a corresponding raster area is not provided with any portion of said presented character and a difference voltage obtains a maximal value if a corresponding raster area is completely provided with a portion of said presented character; algebraically summing said plurality of difference voltages to produce a summation voltage; combining said plurality of difference voltages and said summation voltage in said resistor networks; and comparing each of the voltages produced by said resistor networks in response to said combining to a threshold level.
Claim 2
Dependent Claim
244 words
In a character classifying process wherein a presented character is partitioned into a plurality of raster areas, voltages representative of the light intensity of said raster areas are combined in resistor networks representing predetermined classes of characters to produce output voltages and each of said voltages is compared to a comparison voltage to determine which of said predetermined classes said presented character corresponds, an improved method for reducing the influence of variations in contrast between the presented character and its background and variations in background brightness on the character classifying process, comprising the steps of: generating a reference voltage representing the light intensity of a discrete background area that is not provided with any portion of said presented character; producing a plurality of difference voltages, each of said difference voltages being proportional to the difference between said reference voltage and a voltage representative of the light intensity of a corresponding raster area, whereby a difference voltage obtains a minimal value if a corresponding raster area is not provided with any portion of said presented character and a difference voltage obtains a maximal value if a corresponding raster area is completely provided with a portion of said presented character; algebraically summing said plurality of difference voltages to produce a summation voltage; combining said plurality of difference voltages and said summation voltage in said resistor networks; and comparing each of the voltages produced by said resistor networks in response to said combining to a threshold level.
Claim 3
Dependent Claim
16 words
The improved method of claim 1 wherein said threshold level is equal to said summation voltage.
Claim 4
Dependent Claim
53 words
The improved method of claim 2 wherein said step of generating a reference voltage comprises the steps of: scanning a plurality of those background areas not provided with any portion of said presented character to produce a corresponding plurality of background voltages; and averaging the produced background voltages to generate said reference voltage.
Claim 5
Dependent Claim
226 words
Apparatus for classifying a presented character as being one of a plurality of predetermined types wherein said presented character is imaged onto a raster field having a plurality of raster areas, comprising: an array of photosensor means forming said raster field for producing voltages in accordance with the intensity of light projected thereon by said presented character; a further photosensor means for producing a reference voltage in accordance with the intensity of light projected thereon by the background of said presented character; difference means coupled to said array of photosensor means and said further photosensor means for producing a plurality of difference voltages, each of said difference voltages being proportional to the difference between said reference voltage and a voltage produced by a corresponding one of said array of photosensor means; summing means coupled to said difference means for algebraically summing said difference voltages to produce a summation voltage; resistor networks representing said predetermined types coupled to said difference means and said summing means for combining difference voltages and said summation voltage to produce output voltages, each of said output voltages representing a relation between said presented character and a corresponding one of said predetermined types; and comparison means coupled to said resistor networks for comparing each of said output voltages with a comparison voltage for determining which of said output voltages represents a predetermined relation.
Claim 6
Dependent Claim
226 words
Apparatus for classifying a presented character as being one of a plurality of predetermined types wherein said presented character is imaged onto a raster field having a plurality of raster areas, comprising: an array of photosensor means forming said raster field for producing voltages in accordance with the intensity of light projected thereon by said presented character; a further photosensor means for producing a reference voltage in accordance with the intensity of light projected thereon by the background of said presented character; difference means coupled to said array of photosensor means and said further photosensor means for producing a plurality of difference voltages, each of said difference voltages being proportional to the difference between said reference voltage and a voltage produced by a corresponding one of said array of photosensor means; summing means coupled to said difference means for algebraically summing said difference voltages to produce a summation voltage; resistor networks representing said predetermined types coupled to said difference means and said summing means for combining difference voltages and said summation voltage to produce output voltages, each of said output voltages representing a relation between said presented character and a corresponding one of said predetermined types; and comparison means coupled to said resistor networks for comparing each of said output voltages with a comparison voltage for determining which of said output voltages represents a predetermined relation.
Claim 7
Dependent Claim
26 words
The apparatus of claim 4 wherein said Comparison means is additionally coupled to said summing means whereby said comparison voltage is equal to said summation voltage.
Claim 8
Dependent Claim
50 words
The apparatus of claim 5 wherein said further photosensor means comprises a plurality of photosensor means for scanning only background areas of said presented character; and means for producing a reference voltage having a value equal to the average value of the voltages produced by said plurality of photosensor means.
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) | 1976-06-04 | 1976-12-04 | 1977-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-04 | 1980-12-04 | 1981-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-04 | 1984-12-04 | 1985-06-05 | $7700.00 | Window Closed / Lapsed |