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EP0855830A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Text/line art and halftone discrimination for pixel resolution enhancement

Assignee: HP Inc
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Filing: 1997-09-10
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Granted: —
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Expires: 2017-09-10
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Abstract

Abstract Text and line art image data is distinguished from halftone image data for selectively enhanced rendering thereof. Specifically, a method of rendering a raster pixel image from a stored bitmap (40, 50) includes (i) determining whether an orphan pixel (54, 58, 140, 146) is detected within a bounded sampling window (52, 56, 122, 124, 126, 128, 130) of the bitmap, and, (ii) processing at least one selected pixel (136) of the bitmap within the sampling window relative to the determining of whether an orphan pixel is detected. In general, an orphan pixel is defined as an isolated white or black pixel in a halftone image. In one embodiment, an orphan pixel (54, 58, 140, 146) is recognized as having a predefined pixel value and as having no other pixels with that value adjacent thereto within the sampling window. In the event an orphan pixel is detected within the window, then the bitmap within the window is determined to be halftone image data and the selected pixel is processed accordingly. In the event an orphan pixel does not exist within the window, then the bitmap within the window is recognized as text or line art image data and processed respectively.

Inventors

  • 👤 James G. Bearss
  • 👤 Eugene A. Roylance
  • 👤 Terry M. Nelson
  • 👤 Arlin R. Jones

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 11:25
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40062

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 85 words
A method of rendering a raster pixel image from a stored bitmap (50), the bitmap having at least one bit per pixel representation, the method comprising: (a) determining whether an orphan pixel (54, 58, 140, 146) is detected within one or more bounded windows (52, 56, 122, 124, 126, 128, 130) of the bitmap (50); and, (b) processing at least one selected pixel (136) of the bitmap within the one or more bounded windows relative to the determining of whether an orphan pixel is detected.
Claim 2
Dependent Claim 34 words
The method of claim 1 wherein the orphan pixel (54, 58, 140, 146) has a pixel value that is unique relative to any adjacent pixel (142, 148) within the one or more bounded windows.
Claim 3
Dependent Claim 36 words
The method of claim 1 wherein the orphan pixel (54, 58, 140, 146) has an opposite pixel value relative to a pixel value of any adjacent pixel (142, 148) within the one or more bounded windows.
Claim 4
Dependent Claim 29 words
The method of claim 1 wherein the orphan pixel (54, 58, 140, 146) is defined, generally, as an isolated white (140) or black (146) pixel in the bitmap (50).
Claim 5
Dependent Claim 123 words
The method of claim 1 wherein the orphan pixel (54, 58, 140, 146) has a pixel value of a logical " zero " in the event a pixel value of each adjacent pixel is a logical " non-zero " within the one or more bounded windows, and wherein the orphan pixel has a pixel value of a logical " non-zero " in the event a pixel value of each adjacent pixel is a logical " zero " within the one or more bounded windows, and wherein the orphan pixel has a pixel value of a logical " one " in the event a pixel value of each adjacent pixel is not a logical " one " within the one or more bounded windows.
Claim 6
Dependent Claim 36 words
The method of claim 1 further including, in the event an orphan pixel is detected within the one or more windows, processing the at least one selected pixel (136) of the bitmap as a halftone image.
Claim 7
Dependent Claim 91 words
The method of claim 1 further including, in the event an orphan pixel (54, 58, 140, 146) is detected within the one or more windows, processing the at least one selected pixel (136) of the bitmap as a halftone image, and then, alternatively: (a) processing next selected pixels as text/line art image data until a next orphan pixel is detected; or, (b) processing next selected pixels as halftone image data until a counter expires; or (c) processing next selected pixels as halftone image data until a next orphan pixel is detected.
Claim 8
Dependent Claim 44 words
The method of claim 1 further including, in the event an orphan pixel (54, 58, 140, 146) is not detected within the one or more windows, processing the at least one selected pixel (136) of the bitmap as text or line art image data.
Claim 9
Independent Claim 44 words
A method of forming a pixel matrix (40, 50) for a halftone image, the pixel matrix having at least one bit per pixel representation, the method comprising generating a pixel pattern such that an orphan pixel (54, 58, 140, 146) exists within the pattern.
Claim 10
Independent Claim 70 words
An apparatus for rendering a raster pixel image from a stored bitmap (50), comprising: (a) means for detecting an orphan pixel (54, 58, 140, 146) within one or more bounded windows (52, 56, 122, 124, 126, 128, 130) of the bitmap; and, (b) means for processing at least one selected pixel (136) of the bitmap within the one or more bounded windows relative to whether an orphan pixel is detected.

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