Converting between write-white, write-black and neutral bitmaps
Patent 5258854 Issued on November 2, 1993. Estimated Expiration Date: 
December 6, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
December 6, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesApparatus and method for correcting contour line pattern images Image processing apparatus Method for edge enhanced error diffusion Facsimile apparatus Image processing method and system Image processing apparatus Image quality control system for an image processing system Patent #: 5166810 InventorAssigneeApplicationNo. 802791 filed on 12/06/1991US Classes:358/445, Signal sampling and conversion358/3.07, Rescreening (e.g., converting spatial resolution)358/447, Signal enhancing358/451, Picture size conversion382/257, Dilation or erosion (e.g., opening or closing)382/299Raising or lowering the image resolution (e.g., subpixel accuracy)ExaminersPrimary: Coles, Sr., Edward L.Assistant: Lee, Fan Attorney, Agent or FirmInternational ClassH04N 001/40AbstractA bitmap to be prepared for printing by a printing process with a characteristic dilation or erosion artifact, is initially increased in resolution by a selected factor. The bitmapped image is then increased or decreased in size, at the increased resolution, by an amount necessary to compensate for the characteristic erosion or dilation of the printing process. The bitmap is rescanned, or reduced in resolution, to the original resolution of the image. The rescanned image is highly binary in appearance, but will include a number of gray level pixels in areas where it has been increased in size. Prior to printing, the pixel values are subjected to a quantizing process where gray level pixel values are reduced to binary values, preferably through an error diffusion process which operates only on gray pixels. The process of increasing the bitmap resolution may include a step of smoothing halfbitting.Other References
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