EP0055834A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Reprographic apparatus capable of reproducing various tone and line originals and methods of operation thereof
Assignee: International Business Machines Corp
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Filing: 1981-12-09
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Granted: —
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Expires: 2001-12-09
Abstract
Abstract A document scanner 10 scans a document to be reproduced and the serial output data (PEL's) is provided to a system controller 30 and to an input buffer means 14. The controller 30 provides control signals on line 50 to a print decision multiplexor 48 which can receive inputs on lines 44, 46,54. The input on 54 is selected when a line copy algorithm is to be used to control printing, the input on line 44 when a continuous tone print algorithm is to be used to central printing and the input on line 46 is to be used when a third algorithm is to be used suitable for areas of an original not clearly continuous tone or line tone. The appropriate line 44, 46, 54 is selected in accordance with the sequence of data representing the original. For this purpose gradient logic means 26 is connected by busses 16, 18, 20, 22, 24 to selected storage positions of the buffer means 14 and generates a gradient signal on line 28 for each PEL. Similarly look ahead logic means 32 are connected by busses 20', 22', 24' to selected storage positions of the buffer means 14. The look ahead means 32 provide signals on lines 34, 36 indicative of whether any selected storage position respectively holds a white valued or black valued PEL. In addition hysteresis counters 40 provide signals on lines 58 through 96 indicative of the preceding operational mode and/or preceding PEL values. Latches 104,106,108,110 provide respectively reference signals indicative of a white threshold level, a black threshold level, a threshold level usuable for line copy and a datum gradient value. The system controller 30 is a data processor and is operative to correlate the signals supplied to it and to generate control signals for the multiplexor block 48.
Inventors
- 👤 Sidney Jard Fox
- 👤 Filip Jay Yeskel
- 👤 William John Zimmermann
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 19:33
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40062; G; G06; G06V; G06V30/00; G06V30/40; G06V30/41; G06V30/413; H04N1/403
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
146 words
A method of reproducing an original represented by a serial stream of digital data, each item of data having a PEL value corresponding to the value of a surface charactersitic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said method comprising selecting items of data having grey PEL values between predetermined white and black threshold values and being characterised by determining, at least for each selected item of data, whether any item of data in a group of items of data corresponding to a group of elemental areas ( PEL's) of the original contiguous with the elemental area (PEL) corresponding to the selected item of data, has a PEL value other than a grey PEL value, and if so, operating the apparatus according to a first algorithm and, if not, operating the apparatus according to a second algorithm.
Claim 2
Independent Claim
146 words
A method of reproducing an original represented by a serial stream of digital data, each item of data having a PEL value corresponding to the value of a surface charactersitic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said method comprising selecting items of data having grey PEL values between predetermined white and black threshold values and being characterised by determining, at least for each selected item of data, whether any item of data in a group of items of data corresponding to a group of elemental areas ( PEL's) of the original contiguous with the elemental area (PEL) corresponding to the selected item of data, has a PEL value other than a grey PEL value, and if so, operating the apparatus according to a first algorithm and, if not, operating the apparatus according to a second algorithm.
Claim 3
Dependent Claim
36 words
A method as claimed in claim 1, further characterised by operating the apparatus according to a third algorithm for items of data not selected and having PEL values not between the white and black threshold values.
Claim 4
Independent Claim
41 words
A method as claimed in claim I or 2, further characterised in that the third alogirthm is a line copy algorithm, the second algorithm is a continuous tone copy algorithm and the first algorithm is a biased continuous tone copy algorithm.
Claim 5
Dependent Claim
287 words
Apparatus for reproducing an original represented by a serial stream of digitial data, each item of data having a PEL value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said apparatus being capable of operating in more than one mode to produce copies of different or mixed nature (e.g. half tone, line or printed) originals and comprising buffer means for receiving and buffering the serial stream of data; means for comparing the value of each item of data with first and second threshold values and operable to generate contrast signals indicative of whether the PEL value is greater than the first threshold value, between the threshold values, or below the second threshold value; first means effective in operation to cause the apparatus to operate in a first mode according to a first algorithm; second means effective in operation to cause the apparatus to operate in a second mode according to a second algorithm; and selection means connected to receive the contrast signals, and operative selectively to render the first or second means operative, said apparatus being characterised by further comprising look ahead means connected to receive the PEL values successively stored in a first group of buffer positions and operative to generate a succession of selection signals indicative of whether any PEL value in each group lies in the band of values between the first and second threshold values or outside that band, each selection signal being associated with the PEL value occupying a particular location in the first group, being supplied to the selection means and being used by the selection means in selecting the operational mode of the apparatus.
Claim 6
Dependent Claim
287 words
Apparatus for reproducing an original represented by a serial stream of digitial data, each item of data having a PEL value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said apparatus being capable of operating in more than one mode to produce copies of different or mixed nature (e.g. half tone, line or printed) originals and comprising buffer means for receiving and buffering the serial stream of data; means for comparing the value of each item of data with first and second threshold values and operable to generate contrast signals indicative of whether the PEL value is greater than the first threshold value, between the threshold values, or below the second threshold value; first means effective in operation to cause the apparatus to operate in a first mode according to a first algorithm; second means effective in operation to cause the apparatus to operate in a second mode according to a second algorithm; and selection means connected to receive the contrast signals, and operative selectively to render the first or second means operative, said apparatus being characterised by further comprising look ahead means connected to receive the PEL values successively stored in a first group of buffer positions and operative to generate a succession of selection signals indicative of whether any PEL value in each group lies in the band of values between the first and second threshold values or outside that band, each selection signal being associated with the PEL value occupying a particular location in the first group, being supplied to the selection means and being used by the selection means in selecting the operational mode of the apparatus.
Claim 7
Dependent Claim
28 words
Apparatus as claimed in claim 4, further characterised by comprising hysteresis means operable to generate and store hysteresis signals representative of preceeding operational mode and/or preceeding PEL values.
Claim 8
Dependent Claim
85 words
Apparatus as claimed in claim 5, further characterised in that the hysteresis means comprise a first x-counter and a first y-counter associated with a first mode of operation of the apparatus, a first predetermined value being set in the counters in response to detection by the apparatus of a first predetermined data sequence in the incoming stream of data and the values in the first counters being decremented in response to detection of a subsequent second predetermined data sequence in the incoming stream of data.
Claim 9
Dependent Claim
86 words
Apparatus as claimed in claim 6, further characterised in that the hysteresis means further comprise a second x-counter and a second y-counter associated with a second mode of operation of the apparatus, a second predetermined value being set in the second counters in response to detection by the apparatus of a third predetermined data sequence in the incoming stream of data and the values in the second counters being decremented in response to detections of a subsequent fourth predetermined data sequence in the incoming data sequence.
Claim 10
Dependent Claim
57 words
Apparatus as claimed in claim 6 or 7, in which the stream of incoming data is generated by scanning the original in the y-direction, further characterised in that each y-counter has an associated serial storage shift register having a number of stages equal to the number of P EL 's in the y-scan direction of the original.
Claim 11
Dependent Claim
158 words
9 . Apparatus as claimed in any one of claims 4 to 8, further characterised by comprising gradient means connected to receive the PEL values stored in a second group of buffer positions and operative to generate for each second group a gradient signal, the gradient signal being associated with the particular PEL value occupying a predetermined buffer location in the second group and having a value dependent on the rate of change of the surface characteristic in a region of the original contiguous to the PEL corresponding to the particular PEL value; means for comparing the value of each generated gradient signal with a predetermined datum gradient value and operable to generate transition signals indicative of whether the value of each generated gradient signal is greater or smaller than the datum gradient value, said transition signals being supplied to the selection means and being used by the selection means in selecting the operational mode of the apparatus.
Claim 12
Independent Claim
239 words
A method of reproducing an original represented by a serial stream of digital data, each item of data having a value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said method comprising selecting items of data having grey values between predetermined white and black threshold values; determining, at least for each selected grey valued item of data, a gradient value dependent on the rate of change of the surface characteristic in a region of the original contiguous to the PEL corresponding to the item of data; comparing each determined gradient value with a predetermined gradient value; and using the result of the comparison in the selection of an operational mode, from a plurality of operational modes, for reproducing the original, and said method being characterised in that, when the determined gradient value for a subject item of data bears a first predetermined relationship to the predetermined gradient value, the operational mode is further selected by determining whether the values of all the items of data corresponding to elemental areas of the original in a predetermined area contiguous with the subject elemental area lie in-the range between the predetermined white and black threshold values or whether any item of that data has a value outside that range, and selecting one or other of two alternative operational modes according to the result of the determination.
Claim 13
Independent Claim
239 words
A method of reproducing an original represented by a serial stream of digital data, each item of data having a value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said method comprising selecting items of data having grey values between predetermined white and black threshold values; determining, at least for each selected grey valued item of data, a gradient value dependent on the rate of change of the surface characteristic in a region of the original contiguous to the PEL corresponding to the item of data; comparing each determined gradient value with a predetermined gradient value; and using the result of the comparison in the selection of an operational mode, from a plurality of operational modes, for reproducing the original, and said method being characterised in that, when the determined gradient value for a subject item of data bears a first predetermined relationship to the predetermined gradient value, the operational mode is further selected by determining whether the values of all the items of data corresponding to elemental areas of the original in a predetermined area contiguous with the subject elemental area lie in-the range between the predetermined white and black threshold values or whether any item of that data has a value outside that range, and selecting one or other of two alternative operational modes according to the result of the determination.
Claim 14
Dependent Claim
330 words
Apparatus for reproducing an original represented by a serial stream of digital data, each item of data having a PEL value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said apparatus being capable of operating in more than one mode to produce copies of different or mixed nature (e.g. half tone, line or printed) originals and comprising buffer means for receiving and buffering the serial stream of data; means for comparing the value of each item of data with first and second threshold values and operable to generate contrast signals indicative of whether the item value is greater than the first threshold value, between the threshold levels or below the second threshold value; gradient means connected to receive the PEL values stored in a first group of buffer positions and operable to generate for each first group a gradient value signal which is associated with the PEL value occupying a particular location in the first group; means for comparing the generated gradient values with a predetermined datum gradient value and operable to generate transition signals indicative of whether the generated gradient value is greater or less than the predetermined datum gradient value; and controller means, connected to receive the stream of digital data together with the transition signals, for selecting the operational mode of the apparatus, said apparatus being characterised by further comprising look ahead means connected to receive the PEL values stored in a second group of buffer positions and operable to generate a selection signal for each group indicative of whether any PEL value in the group lies in the band of values between the first and second threshold values or outside that band, each selection signal being associated with the PEL value occupying a particular location in the second group, being supplied to the controller means, and being used by the controller means in selecting the operational mode of the apparatus.
Claim 15
Dependent Claim
330 words
Apparatus for reproducing an original represented by a serial stream of digital data, each item of data having a PEL value corresponding to the value of a surface characteristic (e.g. reflectance) of the elemental area (PEL) of the original represented by the item of data, said apparatus being capable of operating in more than one mode to produce copies of different or mixed nature (e.g. half tone, line or printed) originals and comprising buffer means for receiving and buffering the serial stream of data; means for comparing the value of each item of data with first and second threshold values and operable to generate contrast signals indicative of whether the item value is greater than the first threshold value, between the threshold levels or below the second threshold value; gradient means connected to receive the PEL values stored in a first group of buffer positions and operable to generate for each first group a gradient value signal which is associated with the PEL value occupying a particular location in the first group; means for comparing the generated gradient values with a predetermined datum gradient value and operable to generate transition signals indicative of whether the generated gradient value is greater or less than the predetermined datum gradient value; and controller means, connected to receive the stream of digital data together with the transition signals, for selecting the operational mode of the apparatus, said apparatus being characterised by further comprising look ahead means connected to receive the PEL values stored in a second group of buffer positions and operable to generate a selection signal for each group indicative of whether any PEL value in the group lies in the band of values between the first and second threshold values or outside that band, each selection signal being associated with the PEL value occupying a particular location in the second group, being supplied to the controller means, and being used by the controller means in selecting the operational mode of the apparatus.
Claim 16
Dependent Claim
143 words
A thresholding mode-switching device for automatically selecting an optimum operational mode for printing copies of documents having a mixed format, said mode-switching device comprising: scanning means operable to generate a stream of pixels representative of the informational-contents of a document; input buffer means operable to store a predetermined number of pixels; gradient means coupled to the buffer means and operable to generate gradient signals representative of the gradient associated with a pixel of interest; look-ahead logic means operable to interrogate pixels displaced relative to the pixel of interest and to output look-ahead signals representative of the reflectance characteristics of the pixels; hysteresis means operable to generate signals representative of the prior type of data; means operable to store predetermined signals representing a desired reflectance characteristic of a document; and a controller means operable to correlate the signals and to generate a print/no-print signal.
Claim 17
Dependent Claim
143 words
A thresholding mode-switching device for automatically selecting an optimum operational mode for printing copies of documents having a mixed format, said mode-switching device comprising: scanning means operable to generate a stream of pixels representative of the informational-contents of a document; input buffer means operable to store a predetermined number of pixels; gradient means coupled to the buffer means and operable to generate gradient signals representative of the gradient associated with a pixel of interest; look-ahead logic means operable to interrogate pixels displaced relative to the pixel of interest and to output look-ahead signals representative of the reflectance characteristics of the pixels; hysteresis means operable to generate signals representative of the prior type of data; means operable to store predetermined signals representing a desired reflectance characteristic of a document; and a controller means operable to correlate the signals and to generate a print/no-print signal.
Claim 18
Dependent Claim
121 words
A thresholding mode-switching device for automatically selecting an optimum operational mode for printing copies of documents having a mixed format, said mode-switching device comprising: scanning means operable to generate a stream of pixels representative of the informational contents of a document; input buffer means operable to store a predetermined number of pixels; look-ahead logic means operable to interrogate pixels displaced relative to the pixel of interest and to output look-ahead signals representative of the reflectance characteristics of the pixels; hysteresis means operable to generate signals representative of the prior type of data; means operable to store predetermined signals representing a desired reflectance characteristic of a document; and a controller means operable to correlate the signals and to generate a print/no-print signal.
Claim 19
Dependent Claim
121 words
A thresholding mode-switching device for automatically selecting an optimum operational mode for printing copies of documents having a mixed format, said mode-switching device comprising: scanning means operable to generate a stream of pixels representative of the informational contents of a document; input buffer means operable to store a predetermined number of pixels; look-ahead logic means operable to interrogate pixels displaced relative to the pixel of interest and to output look-ahead signals representative of the reflectance characteristics of the pixels; hysteresis means operable to generate signals representative of the prior type of data; means operable to store predetermined signals representing a desired reflectance characteristic of a document; and a controller means operable to correlate the signals and to generate a print/no-print signal.
Claim 20
Dependent Claim
61 words
A device as claimed in claim 13, wherein the hysteresis means includes: a first set of counters operable for storing a plurality of counts representative of hysteresis in the X-direction; a second set of counters operable for storing a plurality of counts representative of hysteresis in the Y-direction; and a set of serial memories coupled to the second set of counters.
Claim 21
Dependent Claim
99 words
In a document reproduction device wherein a document is being scanned, thresholded and reproduced, an improved thresholder for processing and printing documents having a continuous tone format or a line copy format comprising: means for buffering a stream of video pixels representative of the information contents of the document; means for generating a look-ahead signal representative of the reflectance characteristic of PELs following the PEL of interest; means for storing level information signals representative of the document quality to be reproduced; and control means for correlating the signals and selecting an optimum thresholder for processing text or continuous tone.
Claim 22
Dependent Claim
99 words
In a document reproduction device wherein a document is being scanned, thresholded and reproduced, an improved thresholder for processing and printing documents having a continuous tone format or a line copy format comprising: means for buffering a stream of video pixels representative of the information contents of the document; means for generating a look-ahead signal representative of the reflectance characteristic of PELs following the PEL of interest; means for storing level information signals representative of the document quality to be reproduced; and control means for correlating the signals and selecting an optimum thresholder for processing text or continuous tone.
Claim 23
Dependent Claim
105 words
Method for processing and printing a mixed format document, said method comprising the following steps: a) generating a stream of digital signals indicative of PELs representing the informational contents of said document; b) selecting one of a plurality of thresholders for processing the digital signals; c) setting a predetermined count within a counting means; d) using the thresholder of step b) for generating "print/no-print" decision for the data of step a); e) decrementing the predetermined count on a PEL of indecision; f) repeating steps d)-e) until the count is zero; and g) switching from the present thresholder to another one of the plurality of thresholders.
Claim 24
Dependent Claim
105 words
Method for processing and printing a mixed format document, said method comprising the following steps: a) generating a stream of digital signals indicative of PELs representing the informational contents of said document; b) selecting one of a plurality of thresholders for processing the digital signals; c) setting a predetermined count within a counting means; d) using the thresholder of step b) for generating "print/no-print" decision for the data of step a); e) decrementing the predetermined count on a PEL of indecision; f) repeating steps d)-e) until the count is zero; and g) switching from the present thresholder to another one of the plurality of thresholders.
References Cited (Backward Citations)
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