EP0375431A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Bandwidth reduced multi-pass writing of variable gray level digital images
Assignee: Xerox Corp
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Filing: 1989-12-21
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Granted: —
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Expires: 2009-12-21
Abstract
Abstract User-viewable renderings of variable gray level images composed of pixels represented by binary coded codewords are written on a suitable recording medium by one or more pixel generators which have their write responses code matched to the codewords. More particularly, the write responses of the pixel generators (22 a -----) are "code matched" to the codewords by cyclically and bit synchronously stepping them through a series of gray-scale values which are selected to substantially match the binary weights of the respective bits of the codewords. Such code matched pixel generators are selectively write enabled and disabled in response to the logic levels of the successive bits of the codewords that are applied to them, whereby the binary weighted writes any of them performs in response to a given codeword spatially sum to form a pixel having approximately the same gray-scale value as the given codeword.
Inventors
- 👤 David L. Hecht
- 👤 Robert A. Sprague
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-31 08:48
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40025; H04N1/40037
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
211 words
A system for producing user-viewable renderings of digitally represented, variable gray level images; said system including at least one pixel generator (22 a ---- ) having a controllable gray-scale write response for writing said images on a recording medium in response to fixed length, multi-bit codewords which represent respective pixels of said images; said codewords being binary coded so that each of their bits has a predetermined binary weight; means (23) for bit serially applying certain of said codewords to said pixel generator, said codewords being sequentially applied to said pixel generator at a normalized pixel printing rate for selectively write enabling and disabling said pixel generator at a predetermined bit rate in response to first logic level and second logic level bits, respectively, of one after another of said codewords; and modulator means (25) coupled to said pixel generator for cyclically stepping its write response through a series of gray-scale values selected to substantially match the binary weights of the bits of said codewords; the write response of said pixel generator being cycled at said normalized pixel printing rate and being stepped through said bit weight matching gray-scale values at said bit rate for code matching said pixel generator to said codewords for multi-pass writing of the pixels they represent.
Claim 2
Independent Claim
211 words
A system for producing user-viewable renderings of digitally represented, variable gray level images; said system including at least one pixel generator (22 a ---- ) having a controllable gray-scale write response for writing said images on a recording medium in response to fixed length, multi-bit codewords which represent respective pixels of said images; said codewords being binary coded so that each of their bits has a predetermined binary weight; means (23) for bit serially applying certain of said codewords to said pixel generator, said codewords being sequentially applied to said pixel generator at a normalized pixel printing rate for selectively write enabling and disabling said pixel generator at a predetermined bit rate in response to first logic level and second logic level bits, respectively, of one after another of said codewords; and modulator means (25) coupled to said pixel generator for cyclically stepping its write response through a series of gray-scale values selected to substantially match the binary weights of the bits of said codewords; the write response of said pixel generator being cycled at said normalized pixel printing rate and being stepped through said bit weight matching gray-scale values at said bit rate for code matching said pixel generator to said codewords for multi-pass writing of the pixels they represent.
Claim 3
Dependent Claim
25 words
A system as claimed in Claim 1, wherein said codewords are composed of symmetrically weighted bits (Fig. 4, Fig. 5), whereby said codewords are balanced.
Claim 4
Dependent Claim
28 words
A system as claimed in Claim 1, wherein said codewords are composed of assymmetrically weighted bits (Fig. 7) which are ordered to enhance the balance of such codewords.
Claim 5
Independent Claim
25 words
A system as claimed in any one of Claims 1-3, wherein said pixel generator is an optical pixel generator, and said recording medium is photosensitive.
Claim 6
Dependent Claim
114 words
A system as claimed in Claim 4, wherein said pixel generator comprises an illuminator for supplying a light beam, an electrooptic element (46) having an optically polished surface (47) for totally internally reflecting said light beam, and a pair of neighboring electrodes (45) intimately electrically coupled to said surface; said codewords are bit serially applied to said electrodes for producing a voltage drop between said electrodes which is dependent on the logic levels of said bits, whereby said light beam is modulated in accordance with said bits, said recording medium (55) is exposed by the modulated light beam while advancing at a substantially constant speed in a process direction relative to said pixel generator.
Claim 7
Dependent Claim
32 words
A system as claimed in Claim 4 or Claim 5, wherein said modulator means intensity modulates said optical pixel generator for cyclically stepping its write response through said series of gray-scale values.
Claim 8
Dependent Claim
33 words
A system as claimed in Claim 4 or Claim 5, wherein said modulator means pulse width modulates said optical pixel generator for cyclically stepping its write response through said series of gray-scale values.
Claim 9
Dependent Claim
35 words
A system as claimed in Claim 5, wherein said modulator means amplitude modulates the voltage drop between said electrodes for cyclically stepping the write response of said pixel generator through said series of gray-scale values.
Claim 10
Independent Claim
201 words
A method for producing user-viewable renderings of digitally represented, variable gray level images, using a pixel generator having a controllable gray-scale write response for writing on a recording medium in response to fixed-length, multi-bit codewords, the method comprising the steps of: bit serially applying, to the pixel generator, multi-bit codewords of the said fixed length, which codewords represent respective pixels of said images and are binary coded so the each of their bits has a predetermined binary weight, said codewords being sequentially applied to said pixel generator at a normalized pixel printing rate for selectively write enabling and disabling said pixel generator at a predetermined bit rate in response to first logic level and second logic level bits, respectively, of one after another of said codewords; and cyclically stepping the write response of the pixel generator through a series of gray-scale values selected to substantially match the binary weights of the bits of said codewords; the write response of said pixel generator being cycled at said normalized pixel printing rate and being stepped through said bit weight matching gray-scale values at said bit rate for code matching said pixel generator to said codewords for multi-pass writing of the pixels they represent.
Claim 11
Independent Claim
201 words
A method for producing user-viewable renderings of digitally represented, variable gray level images, using a pixel generator having a controllable gray-scale write response for writing on a recording medium in response to fixed-length, multi-bit codewords, the method comprising the steps of: bit serially applying, to the pixel generator, multi-bit codewords of the said fixed length, which codewords represent respective pixels of said images and are binary coded so the each of their bits has a predetermined binary weight, said codewords being sequentially applied to said pixel generator at a normalized pixel printing rate for selectively write enabling and disabling said pixel generator at a predetermined bit rate in response to first logic level and second logic level bits, respectively, of one after another of said codewords; and cyclically stepping the write response of the pixel generator through a series of gray-scale values selected to substantially match the binary weights of the bits of said codewords; the write response of said pixel generator being cycled at said normalized pixel printing rate and being stepped through said bit weight matching gray-scale values at said bit rate for code matching said pixel generator to said codewords for multi-pass writing of the pixels they represent.
References Cited (Backward Citations)
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