GB1451917A - Electrical encoder - Google Patents
Electrical encoderInfo
- Publication number
- GB1451917A GB1451917A GB5640973A GB5640973A GB1451917A GB 1451917 A GB1451917 A GB 1451917A GB 5640973 A GB5640973 A GB 5640973A GB 5640973 A GB5640973 A GB 5640973A GB 1451917 A GB1451917 A GB 1451917A
- Authority
- GB
- United Kingdom
- Prior art keywords
- levels
- threshold
- outputs
- input
- clockpulses
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/403—Discrimination between the two tones in the picture signal of a two-tone original
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
- G06V10/00—Arrangements for image or video recognition or understanding
- G06V10/20—Image preprocessing
- G06V10/28—Quantising the image, e.g. histogram thresholding for discrimination between background and foreground patterns
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M1/00—Analogue/digital conversion; Digital/analogue conversion
- H03M1/12—Analogue/digital converters
- H03M1/34—Analogue value compared with reference values
- H03M1/36—Analogue value compared with reference values simultaneously only, i.e. parallel type
- H03M1/361—Analogue value compared with reference values simultaneously only, i.e. parallel type having a separate comparator and reference value for each quantisation level, i.e. full flash converter type
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Analogue/Digital Conversion (AREA)
- Facsimile Image Signal Circuits (AREA)
- Facsimile Scanning Arrangements (AREA)
Abstract
1451917 Electrical encoder INTERNATIONAL BUSINESS MACHINES CORP 5 Dec 1973 [26 Dec 1972] 56409/73 Heading G4R A circuit for providing a digital signal 18 when an analog input 14 exceeds a threshold comprises means 21-28 for comparing the input with fixed threshold levels and means 40, 50, 60, 70, 80 for selecting one of these levels to be the threshold in dependence on the results of previous comparisons. Input 14 is derived from the scanning 11, 13 of a document 12, and the output 18 indicates the presence of a "black" or a "white" bit on the scanned document. Signal 14 is compared at 21- 27 with (increasing) voltages V1-V7 from a resistor chain 28 which provide levels 1-7 expressed as percentages of absolute black, levels 1 and 4 (10%, 24.3%) corresponding to light and dark (highcontrast) printing. The outputs from 21-27 are stored (under the control of clockpulses 17') in latches 30 from which the signals corresponding to levels 1-4 are fed to gates 41-44). The outputs from 30 also pass to circuits 70, 80 which cause counters 52, 62 to be in- or decremented by clockpulses 17". The outputs from 52, 62 are decoded and fed back to 70, 80. The most significant output bits 51, 61 of each counter are fed back to control gates 41-44: they form a Gray code sequence 00-10-11-01 which effectively identifies the output threshold with levels 1 to 4 in turn. In effect, counters 52, 62 record the numbers of certain sets of the levels which have already occurred and adjust the threshold accordingly. The decoder outputs co-operate with 70 and 80 to ensure that 52, 62 do not exceed their pre-set minimum and maximum counts, and that the level transitions occur only in the order 1-2-3-4-3-2-1.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US31796472A | 1972-12-26 | 1972-12-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1451917A true GB1451917A (en) | 1976-10-06 |
Family
ID=23236028
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB5640973A Expired GB1451917A (en) | 1972-12-26 | 1973-12-05 | Electrical encoder |
Country Status (4)
Country | Link |
---|---|
JP (1) | JPS4991756A (en) |
DE (1) | DE2363124A1 (en) |
FR (1) | FR2211814B1 (en) |
GB (1) | GB1451917A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2505479A1 (en) * | 1975-02-10 | 1976-08-19 | Siemens Ag | PHASE COMPARATOR AND PROCEDURE FOR ITS OPERATION |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
IT545970A (en) * | 1954-12-29 | 1900-01-01 | ||
US3662341A (en) * | 1970-09-25 | 1972-05-09 | Ibm | Video-derived segmentation-gating apparatus for optical character recognition |
-
1973
- 1973-11-20 FR FR7342446A patent/FR2211814B1/fr not_active Expired
- 1973-12-05 GB GB5640973A patent/GB1451917A/en not_active Expired
- 1973-12-14 JP JP48138865A patent/JPS4991756A/ja active Pending
- 1973-12-19 DE DE2363124A patent/DE2363124A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
JPS4991756A (en) | 1974-09-02 |
FR2211814B1 (en) | 1976-06-25 |
FR2211814A1 (en) | 1974-07-19 |
DE2363124A1 (en) | 1974-06-27 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed [section 19, patents act 1949] | ||
PCNP | Patent ceased through non-payment of renewal fee |