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EP0089931A2
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EP
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Apparatus for scanning and digitally processing half-tone images
Assignee: Olivetti SpA
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Filing: 1983-03-17
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Granted: —
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Expires: 2003-03-17
Abstract
Abstract The apparatus comprises an optical scanning device (1, 2) for scanning elements or portions of an image or for providing corresponding electrical image signals (V) which are fed to a plurality of threshold comparator circuits (C 1 to C 7 ) where they are compared with respective reference signals (S 1 to S 7 ) which define a scale of half tones (B, G, to G 6 , W). The apparatus further includes a digital-signal generator circuit (23, 24) arranged to generate a plurality of digital signal combinations each of which is indicative of a respective predetermined matrix pattern of white or black points associated with a respective half tone of the scale. This generator circuit (23, 24), in operation, outputs the combination of digital signals relating to the pattern associated with the half tone currently indicated by the signals provided by the threshold comparator circuits (C, to C 7 ). The apparatus effects the electronic processing of half-tone images and may further include means (36) for processing white/black image portions, and detection and switching means (27, 28) arranged to identify the transitions from half-tone image portions to white/black image portions and vice versa.
Inventors
- 👤 Giovanni Ciardiello
- 👤 Ferdinando Augusti
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 10:02
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/403; H04N1/40062; H04N1/405; H04N1/4051
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
161 words
An apparatus for scanning and digitally processing images with half tones, including an optical scanning device (1, 2) for scanning, elemets or portions of an image (O) and. for outputting corresponding electrical image signals (V), and a plurality of threshold comparator circuits (C 1 to C 7 ) for comparing the image signals (V) with respective reference signals (S 1 to S 7 ) which define a scale of half tones (B, G 1 to G 6 , W) characterised in that it further includes a digital-signal generator circuit (23, 24) arranged to generate a plurality of combinations of digital signals, each combination being indicative of a respective predetermined matrix pattern of white or black points associated with a respective half tone of the scale; the digital-signal generator circuit (23, 24), in operation, outputting the combination of digital signals which corresponds to the half tone indicated by the signals output by the threshold comparator circuits (C 1 to C 7 ).
Claim 2
Independent Claim
161 words
An apparatus for scanning and digitally processing images with half tones, including an optical scanning device (1, 2) for scanning, elemets or portions of an image (O) and. for outputting corresponding electrical image signals (V), and a plurality of threshold comparator circuits (C 1 to C 7 ) for comparing the image signals (V) with respective reference signals (S 1 to S 7 ) which define a scale of half tones (B, G 1 to G 6 , W) characterised in that it further includes a digital-signal generator circuit (23, 24) arranged to generate a plurality of combinations of digital signals, each combination being indicative of a respective predetermined matrix pattern of white or black points associated with a respective half tone of the scale; the digital-signal generator circuit (23, 24), in operation, outputting the combination of digital signals which corresponds to the half tone indicated by the signals output by the threshold comparator circuits (C 1 to C 7 ).
Claim 3
Dependent Claim
109 words
An apparatus according to Claim 1, characterised in that it further includes a sampling and control circuit (FF 1 to FF 7 , A 1 to A 6 ) connected between the comparator circuits (C 1 to C 7 ) and the said digital-signal generator circuits (23, 24) and arranged to sample the outputs of the comparator circuits (C 1 to C 7 ) at a predetermined frequency (CK') and, at each sampling, to cause the output by the generator circuit (23, 24) of the combinations of digital signals associated with the half tone indicated by the signals output by the threshold comparator circuits (C to C 7 ).
Claim 4
Dependent Claim
51 words
An apparatus according to Claim 2, characterised in that the said sampling and control circuit (FF 1 to FF 7 , A 1 to A 6 ) includes regulating means (22) arranged to modify the frequency of sampling of the outputs of the threshold comparator circuits (C1 to C 7 ).
Claim 5
Dependent Claim
148 words
An apparatus according to Claim 2 or 3, including a number n of threshold comparator circuits, characterised in that the sampling and control circuit includes n flip-flops (FF 1 to FF 7 ) each of which has its set input connected to the output of one of the threshold comparator circuits (C 1 to C 7 ); the reset inputs of the flip-flops (FF 1 to FF 7 ) being connected to timing pulse generator means (22); and n - 1 AND gates (A 1 to A 6 ); the i'th AND gate having a first input connected to the output of the i'th flip-flop, and a second input connected to the complementary or inverse output of the (i + 1)' the flip-flop; the outputs of the AND gates (A 1 to A 6 ) being connected to the pattern selection inputs of the digital-signal generator circuit (23).
Claim 6
Dependent Claim
64 words
An apparatus according to Claim 3 or 4, characterised in that it further includes an OR gate (25) having a first input connected to the output of the flip-flop (FF ) connected to the threshold comparator circuit (C ) with which the largest value reference signal (S 7 ) is associated, and a second input connected to the output of the digital-signal generator circuit
Claim 7
Independent Claim
113 words
An apparatus for scanning and electronically processing mixed images, that is, comprising half-tone image portions and white/black image portions characterised in that it comprises in combination means (C 1 to C 7 , FF 1 to FF 7 , A 1 to A 6 , 23 to 25) for processing the half-tone image portions according to any one of the preceding claims, means (26) for processing the white/black image portions, and end switching means (27, 28) arranged to identify transitions from half-tone image portions to white/black image portions, and vice versa, and to output correspondingly the signals generated by the means for processing half-tone images or by the means for processing white/black images.
Claim 8
Dependent Claim
86 words
An apparatus according to Claim 6, characterised in that the detection and switching means (27, 28) are arranged to count the number of consecutive image elements with half tones (G 1 to G 6 ) different from the darkest half tone (black) (B) and the lightest half tone (white) (W) of the scale of half tones, and to actuate the means for processing half-tone images and the means for processing white/black images respectively when this number is greater than and, less than a predetermined number (Q)
Claim 9
Dependent Claim
89 words
An apparatus according to Claim 7, characterised in that the detection and switching means comprise, a switch device (28) selectively connectable to the output of the means for processing half-tone images or the output of the means for processing white/black images, and a logic circuit (27), for controlling the switch device (28), connected to the output of the flip-flops (FF 7 , FF 1 ) connected to the comparator circuits (C , C 1 ) having the highest threshold (S ) and the lowest threshold (S 1 ) respectively.
Claim 10
Dependent Claim
110 words
An apparatus according to Claim 8, characterised in that the logic circuit (27) for controlling the switch device (28) includes a counting circuit which initiates a count each time the sampled value of the analogue signal (V) exceeds the lowest reference signal (S 1 ) or falls below the uppermost reference signal (S 7 ) of the threshold comparator circuits (C 1 , C 7 ); the counting circuit stopping the said count each time the sampled value of the analogue signal (V) falls below the lowest reference signal (S ) or exceeds the uppermost reference signal (S ) of these threshold comparator circuits (C 1 , C 7 ).
Claim 11
Independent Claim
98 words
An apparatus according to any one of Claims 6 to 9, characterised in that the said means for processing white/black images include a variable threshold comparison circuit (26) connected to the outputs of the flip-flops (FF 1 to FF ); the comparison circuit (26) being arranged to take as its threshold at the beginning of each line of the examined image the lowest reference signal (S ) of the said reference signals ( S1 to S 7 ), and subsequently to take as its threshold the level of the reference signal last traversed by the analogue signal (V).
Claim 12
Dependent Claim
45 words
An apparatus according to Claim 10, characterised in that a first and a second delay line (DL 1 , DL 2 ) are connected between the switch device (28) and, respectively, the output of the digital-signal generator circuit (23) and, the variable threshold comparison circuit
References Cited (Backward Citations)
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