Apparatus for processing halftone image

An image processing apparatus for estimating a halftone image from an original binary coded image, the original binary coded image including white pixels and black pixels in the form of original binary coded image data, the apparatus comprising:

• memory means for storing the original binary coded image data and for storing a plurality of scanning windows;
• shifting means for superimposing a selected one of said plurality of scanning windows on the original binary coded image data and for shifting said selected one of said plurality of scanning windows relative to the original binary coded image data;
• counting means for counting the number of white pixels or black pixels in the original binary coded image data within the selected one of the plurality of scanning windows superimposed on the original binary coded image data and generating a count result signal in response thereto;
• and
• means for generating an average pixel level matrix proportional to the count result signal and the gain of the selected one of said plurality of scanning windows;
• first judgment means for comparing said average pixel level matrix with a threshold value matrix and generating a first judgment result signal in response thereto;
• second judgment means for performing a predetermined conditional algorithm based on the value counted in said counting circuit and generating a second judgment result signal in response thereto;
• third judgment means for selecting one scanning window from among the plurality of scanning windows in response to said first and second judgment result signals.

An image processing apparatus, for estimating a halftone image from original binary image data in the form of data representing a line of pixels corresponding to a scanning line, comprising:

• (A) memory means for storing a plurality of lines of original binary image data representing a plurality of lines of pixels;
• (B) a plurality of scanning windows for enclosing a predetermined part of said plurality of lines of original binary image data, including therein data representing a target pixel, each of said plurality of scanning windows having a different window configuration so as to enclose a predetermined number of data representing a predetermined number of pixels;
• (C) a counting circuit for counting either one of two components of binary image data so that each of said plurality of scanning windows is assigned a counted value corresponding to the enclosed part of the original binary image data;
• (D) a first judgment circuit for performing a first judgment for each of a first group of said plurality of scanning windows, said first judgment circuit including;
• (i) means for producing binary image data on the basis of the counted value as well as the window configuration;
• and
• (ii) means for comparing a density pattern of the produced binary image data with that of the enclosed original binary image data and for outputting a first judgment signal on the basis of the comparison result;
• (E) a second judgment circuit for performing a second judgment for the second group of said plural kinds of scanning windows, said second judgment circuit having a conditional formula circuit for performing a predetermined conditional algorithm by using the counted values of the second group of said plurality of scanning windows and for outputting a second judgment signal on the basis of a result of the conditional algorithm,
• (F) a third judgment circuit having a predetermined truth table for selecting one scanning window from said plurality of scanning windows in response to the judgment signals outputted from said first and second judgment circuits, and
• (G) means for determining the halftone level of the target pixel on the basis of the selected scanning window.