EP0696132A2
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EP
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A method of high addressability error diffusion
Assignee: Xerox Corp
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Filing: 1995-07-31
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Granted: —
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Expires: 2015-07-31
Abstract
Abstract A method and system implements a high addressability characteristic into an error diffusion process. A grey level value representing a pixel is received. The grey level value has a first resolution which corresponds to an original input resolution. The grey level value is interpolated (S30) to generate subpixel grey level values which correspond to a second resolution. The second resolution is higher than the first resolution and corresponds to the high addressability characteristic. A threshold circuit thresholds the interpolated grey level value and generates (s180) an error value as a result of the threshold. The error value has a resolution corresponding to the first resolution. A portion of the error value is diffused (S190) to adjacent pixels on a next scanline.
Inventors
- 👤 David J. Metcalfe
- 👤 Jeng-Nan Shiau
- 👤 Leon C. Williams
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:54
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4051; H04N1/4052
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
62 words
A method of generating an error from a threshold process, comprising the steps of: (a) thresholding a grey level value of a pixel having a first resolution; and (b) generating an error value as a result of thresholding the grey level value in said step (a), the error value having a second resolution, the second resolution being lower than the first resolution.
Claim 2
Dependent Claim
29 words
The method as claimed in claim 1, further comprising the step of: (c) diffusing the error value to grey level values of pixels adjacent to the pixel being thresholded.
Claim 3
Independent Claim
103 words
A method of diffusing an error generated from thresholding a grey level value representing a pixel, comprising the steps of: (a) receiving the grey level value representing the pixel, the grey level value having a first resolution; (b) converting the grey level value to a second resolution, the second resolution being higher than the first resolution; (c) thresholding the converted grey level value; (d) generating an error value as a result of a threshold determination in said step (c), the error value having a resolution corresponding to the first resolution; and (e) diffusing the error value to grey level values representing adjacent pixels.
Claim 4
Dependent Claim
96 words
The method as claimed in claim 3, wherein said step (b) comprises the substeps of: (b1) computing a first grey level value; and (b2) computing a second grey level value; and preferably further comprises the substep of: (b3) computing a plurality of subpixel grey level values B n , the subpixel grey level values B n being equal to P0 + n(P1-P0)/N, wherein n is equal to 0 to N-1, P0 is equal to the first grey level value, P1 is equal to the second grey value, and N is equal to a high addressability characteristic.
Claim 5
Independent Claim
95 words
The method as claimed in clam 4, wherein said step (d) comprises the substeps of: (d1) calculating a desired output, the desired output being equal to a sum of the first and second grey level values divided by two; (d2) calculating an actual output, the actual output being equal to a number of subpixels being equal to or greater than a threshold value multiplied by a maximum grey level value for a pixel divided by a high addressability characteristic; and (d3) calculating the error to be equal to the desired output minus the actual output.
Claim 6
Independent Claim
59 words
A system for generating an error from a threshold process, comprising: threshold means for thresholding a grey level value of a pixel having a first resolution; and error means for generating an error value as a result of thresholding by said threshold means, the error value having a second resolution, the second resolution being lower than the first resolution.
Claim 7
Dependent Claim
28 words
The system as claimed in claim 6, further comprising: diffusing means for diffusing the error value to grey level values of pixels adjacent to the pixel being thresholded.
Claim 8
Independent Claim
112 words
A system for diffusing an error generated from thresholding a grey level value representing a pixel, comprising: input means for receiving the grey level value representing the pixel, the grey level value having a first resolution; high addressability means for converting the grey level value to a second resolution, the second resolution being higher than the first resolution; threshold means for thresholding the converted grey level value; error means for generating an error value as a result of a threshold determination by said threshold means, the error value having a resolution corresponding to the first resolution; and error diffusing means for diffusing the error value to grey level values representing adjacent pixels.
Claim 9
Dependent Claim
24 words
The system as claimed in claim 8, wherein said high addressability means computes a first grey level value and a second grey level value.
Claim 10
Dependent Claim
116 words
A printing system for rendering marks on a receiving medium, comprising: receiving means for receiving a grey level signal corresponding to a pixel having a first resolution; interpolation means for converting the grey level signal to a second resolution, the second resolution being higher than the first resolution; binarization means for binarizing the converted grey level signal so as to output a binary signal and an error signal, the error signal having a resolution equal to the first resolution; diffusing means for diffusing the error value to grey level signals corresponding to pixels adjacent to the pixel having the first resolution; and rendering means for converting the binary signal into a mark on the receiving medium.
References Cited (Backward Citations)
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