Patents by Inventor David J. Metcalfe
David J. Metcalfe has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6144775Abstract: A method and system implements a dynamic error diffusion process. A grey level value representing a pixel is received. An image segmentation circuit determines an image characteristic of the pixel being processed. A threshold circuit thresholds the grey level value (pixel) and generates an error value as a result of the threshold process. A portion of the error value is diffused to adjacent pixels on a next scanline. The distribution of this error value is dynamic in that different sets of weighting coefficients are used based the image characteristic of the processed pixel. One set of coefficients are utilized in processing a pixel having a first image characteristic, and a second set of coefficients are utilized in processing a pixel having a second image characteristic.Type: GrantFiled: November 26, 1997Date of Patent: November 7, 2000Assignee: Xerox CorporationInventors: Leon C. Williams, Jeng-Nan Shiau, David J. Metcalfe
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Patent number: 6061143Abstract: A system and method for processing image data converts a pixel of image data having a first resolution to a plurality of subpixels, the plurality of subpixels representing a second resolution, the second resolution being higher than the first resolution. The plurality of subpixels are thresholded to generate a group of subpixel values for each pixel and a threshold error value. It is then determined if the group of subpixel values from the thresholding process produce a pattern containing an isolated subpixel. If the group of subpixel values from the thresholding process produce a pattern containing an isolated subpixel, the group of subpixel vales is modified to produce a pattern without an isolated subpixel. The modification process produces a subpixel error value which is compensated for localized error before being diffused to adjacent pixels.Type: GrantFiled: April 20, 1998Date of Patent: May 9, 2000Assignee: Xerox CorporationInventors: Stuart A. Schweid, David J. Metcalfe
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Patent number: 5933539Abstract: A printing system for rendering marks on a recording medium receives a multi-level grey scale pixel value representing a pixel having a first resolution. A screening circuit generates a screened multi-level grey scale pixel value equal to (G.sub.L -V.sub.i)+(S.sub.i -Th)*Dmp.sub.Vi *Mod.sub.Eff wherein G.sub.L is the maximum grey level value of the pixel, V.sub.i is equal to the multi-level grey scale pixel value of the first resolution, S.sub.i is equal to a screen value corresponding to a position of the pixel, Th is the threshold value, Dmp.sub.Vi is a video dependent dampening factor, and Mod.sub.Eff is a modulation multiplication factor. An interpolator converts the screened multi-level grey scale pixel value to a second resolution, the second resolution being higher than the first resolution, and a binarization circuit binarizes the converted multi-level grey scale pixel value so as to output a binary signal and an error value, the error value having a resolution equal to the first resolution.Type: GrantFiled: May 30, 1996Date of Patent: August 3, 1999Assignee: Xerox CorporationInventors: David J. Metcalfe, Jeng-Nan Shiau
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Patent number: 5903361Abstract: A method and system assigns an image classification to a multi-level grey scale pixel value. The multi-level grey scale pixel value is modified based on an error generated by previously processed pixels and the image classification of the multi-level grey scale pixel and processed based on the assigned image classification to reduce the number of grey levels in the multi-level grey scale pixel value. An error is generated based on the processing of the modified multi-level grey scale pixel value and a portion of the error is diffused to a next pixel in a fastscan direction and a remaining portion of the error is diffused to pixels in a slowscan direction. The modified multi-level grey scale pixel value referred above includes an error from the previously processed neighboring pixels if the current pixel is classified as being processed as an error diffused pixel.Type: GrantFiled: June 6, 1996Date of Patent: May 11, 1999Assignee: Xerox CorporationInventors: Jeng-Nan Shiau, David J. Metcalfe
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Patent number: 5880857Abstract: A process eliminates pattern shifting artifacts in a printed image by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.Type: GrantFiled: October 10, 1996Date of Patent: March 9, 1999Assignee: Xerox CorporationInventors: Jeng-Nan Shiau, Leon C. Williams, David J. Metcalfe
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Patent number: 5822464Abstract: A printing system for rendering marks on a recording medium receives a multi-level grey scale pixel value representing a pixel having a first resolution. A screening circuit generates a screened multi-level grey scale pixel value equal to (G.sub.L -V.sub.i)+(S.sub.i -Th)*Dmp.sub.vi *Mod.sub.Eff wherein G.sub.L is the maximum grey level value of the pixel, V.sub.i is equal to the multi-level grey scale pixel value of the first resolution, S.sub.i is equal to a screen value corresponding to a position of the pixel, Th is the threshold value, Dmp.sub.vi is a video dependent dampening factor, and Mod.sub.Eff is a modulation multiplication factor. An interpolator converts the screened multi-level grey scale pixel value to a second resolution, the second resolution being higher than the first resolution, and a binarization circuit binarizes the converted multi-level grey scale pixel value so as to output a binary signal and an error value, the error value having a resolution equal to the first resolution.Type: GrantFiled: May 30, 1996Date of Patent: October 13, 1998Assignee: Xerox CorporationInventor: David J. Metcalfe
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Patent number: 5809177Abstract: A process eliminates pattern shifting artifacts in a printed image rendered using a hybrid high addressable error diffusion process by perturbing a threshold/image signal value relationship when a multi-level grey level is binarized. The process utilizes a programmable multi-level grey signal modifying circuit for modifying the multi-level grey signal by a predetermined value according to its grey level. The modified multi-level grey signal is binarized to a binary pixel signal according to a relationship between the modified multi-level grey signal and a threshold value. The process further generates an error corresponding to the relationship and diffuses the error to neighboring pixels. The multi-level grey signal is modified with either random noise multiplied by a grey level dependent coefficient or by a predetermined value from a checkerboard or vertical line pattern. The value from the pattern is dependent upon the grey level and pixel location of the image data.Type: GrantFiled: June 6, 1996Date of Patent: September 15, 1998Assignee: Xerox CorporationInventors: David J. Metcalfe, Jeng-Nan Shiau, Leon C. Williams
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Patent number: 5805724Abstract: A printing system for rendering marks on a recording medium receives a multi-level grey scale pixel value representing a pixel having a first resolution. A screening circuit generates a screened multi-level grey scale pixel value equal to (G.sub.L -V.sub.i)+(S.sub.i -Th)*Dmp.sub.vi *Mod.sub.Eff wherein G.sub.L is the maximum grey level value of the pixel, V.sub.i is equal to the multi-level grey scale pixel value of the first resolution, S.sub.i is equal to a screen value corresponding to a position of the pixel, the image classification of the pixel and a brightness/darkness setting, The threshold value, Dmp.sub.vi is a video dependent dampening factor, and Mod.sub.Eff is a modulation multiplication factor.Type: GrantFiled: September 24, 1996Date of Patent: September 8, 1998Assignee: Xerox CorporationInventors: David J. Metcalfe, Roger L. Triplett, John T. Newell, Xiao-fan Feng
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Patent number: 5787206Abstract: A printing system for rendering marks on a recording medium receives a multi-level grey scale pixel value representing a pixel having a first resolution. A screening circuit generates a screened multi-level grey scale pixel value equal to (G.sub.L -V.sub.i)+(S.sub.i -Th)*Dmp.sub.vi *Mod.sub.Eff wherein G.sub.L is the maximum grey level value of the pixel, V.sub.i is equal to the multi-level grey scale pixel value of the first resolution, S.sub.i is equal to a screen value corresponding to a position of the pixel, Th is the threshold value, Dmp.sub.vi is a video dependent dampening factor, and Mod.sub.Eff is a modulation multiplication factor. An interpolator converts the screened multi-level grey scale pixel value to a second resolution, the second resolution being higher than the first resolution, and a binarization circuit binarizes the converted multi-level grey scale pixel value so as to output a binary signal and an error value, the error value having a resolution equal to the first resolution.Type: GrantFiled: May 30, 1996Date of Patent: July 28, 1998Assignee: Xerox CorporationInventors: Leon C. Williams, Jeng-Nan Shiau, David J. Metcalfe
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Patent number: 5754706Abstract: A system and method for processing image data converts a pixel of image data having a first resolution to a plurality of subpixels, the plurality of subpixels representing a second resolution, the second resolution being higher than the first resolution. The plurality of subpixels are thresholded to generate a group of subpixel values for each pixel and a threshold error value. It is then determined if the group of subpixel values from the thresholding process produce a pattern containing an isolated subpixel. If the group of subpixel values from the thresholding process produce a pattern containing an isolated subpixel, the group of subpixel vales is modified to produce a pattern without an isolated subpixel. The modification process produces a subpixel error value which is diffused in the slowscan direction to adjacent pixels.Type: GrantFiled: June 19, 1996Date of Patent: May 19, 1998Assignee: Xerox CorporationInventors: Stuart A. Schweid, David J. Metcalfe
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Patent number: 5696601Abstract: A method and system implements a redistributive characteristic into an error diffusion process. A grey level value representing a pixel is received. A threshold circuit thresholds the received grey level value and generates an error value as a result of the threshold. A portion of the error value is diffused to adjacent pixels on a next scanline. All the error for a single pixel on the next scanline is accumulated. Since this accumulated error has a greater number of bits than can be stored in a buffer, a portion of the accumulated error is truncated and redistributed to a down stream pixel for inclusion in the downstream pixel's error accumulation process. The grey level value has a first resolution which corresponds to an original input resolution. In a high addressabilty environment, the received grey level value is interpolated to subpixel grey level values before thresholding.Type: GrantFiled: August 3, 1994Date of Patent: December 9, 1997Assignee: Xerox CorporationInventors: David J. Metcalfe, Jeng-Nan Shiau, Leon C. Williams
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Patent number: 5638121Abstract: In a photosenstive device wherein video voltage signals are output from a plurality of photosensors, the photosensors are divided into odd and even subsets. Odd photosensors output video into an odd video channel, and even photosensors output video into an even video channel. The two video signals are time-staggered from each other by one-half cycle. The signals on the odd and even video channels are then multiplexed into a single high-speed channel.Type: GrantFiled: October 8, 1996Date of Patent: June 10, 1997Assignee: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon, Scott L. Tewinkle, David J. Metcalfe
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Patent number: 5608821Abstract: 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 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 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 to adjacent pixels on a next scanline.Type: GrantFiled: August 3, 1994Date of Patent: March 4, 1997Assignee: Xerox CorporationInventors: David J. Metcalfe, Jeng-Nan Shiau, Leon C. Williams
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Patent number: 5528384Abstract: 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 is interpolated to generate subpixel grey level values which correspond to a second resolution. A threshold circuit thresholds the interpolated grey level value. In parallel to the interpolation circuit and threshold circuit is an error circuit which generates a plurality of possible error values. One of the plurality of possible error values is selected based on the number of subpixels exceeding a threshold value. A portion of the selected error value is then diffused to adjacent pixels on a next scanline.Type: GrantFiled: August 3, 1994Date of Patent: June 18, 1996Assignee: Xerox CorporationInventors: David J. Metcalfe, Jeng-Nan Shiau, Leon C. Williams
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Patent number: 5153421Abstract: Sensor array architectures for both analog and digital sensor arrays adapted for single chip applications or abutment with other like arrays to form a composite scanning array, the architecture providing a sensor array in which the array video signal processing circuits, clock circuits, etc. are integrated onto the same chip as the sensor array itself and dark reference sensors are located in-line or apart from the image scanning sensors to avoid gaps in the scan line when several sensor arrays are assembled together.Type: GrantFiled: November 4, 1991Date of Patent: October 6, 1992Assignee: Xerox CorporationInventors: Jagdish C. Tandon, Scott L. Tewinkle, David J. Metcalfe, YungRan Choi, Richard B. Eaton