Multiple measurement noise reducing system using space-variant filters
Halftone picture processing apparatus
Image scanning and recording method
Image processing apparatus with high- and low-resolution image sensors and an edge detector
Digital facsimile/image producing apparatus
Image processing method Patent #: 4841374
ApplicationNo. 857557 filed on 03/25/1992
US Classes:358/3.08, Descreening (e.g., inverse halftone conversion)358/462, Text and image detection and processing358/465, Picture signal thresholding358/466, Variable thresholding technique382/233Including details of decompression
ExaminersPrimary: Coles, Sr., Edward L.
Assistant: Lee, Fan
Attorney, Agent or Firm
International ClassH04N 001/40
AbstractAn image processing system converts unscreened and other halftone images to continuous tone images. Value data is sequencitally generated for successive pixels of a screened or unscreened halftone image. Each image pixel is Sigma filtered with a predetermined set of filter parameters including the filter window size and a Sigma difference range that is applied to determine which pixels in the filter window are counted in determining average window pixel values. An output continuous tone image containing the Sigma filtered pixels is generated for storage and/or processing to a halftone copy or print.