Patent ID: 6101285
Filing Date: 2000-08-08
Classification: G06T,H04N

Abstract:
A method of outputting a continuous tone image comprising the steps of:a) acquiring the halftone digital image data;b) filtering the halftone image in two directions to produce a two-dimensional filtered output; andc) producing a continuous tone output image from said two-dimensional filtered output,wherein said filtering step further comprises:a) operating a one-dimensional filter on the halftone digital image data in a first direction to produce a continuous tone first filter output; andb) operating a one-dimensional filter on said continuous tone first filter output in a second direction to produce a continuous tone second filter output,wherein said first direction filter operating step further comprises:a) inputting gray level value signals for pixels in a line;b) inputting a threshold value signal;c) selecting a pixel and generating a selected pixel pseudo-window which is approximately centered at said selected pixel, wherein said selected pixel pseudo-window includes at least one pixel adjacent to said selected pixel;d) determining an average gray level signal for all pixels in said selected pixel pseudo-window;e) creating adjacent pixel pseudo-windows that are approximately centered at pixels adjacent to said selected pixel and determining average gray level value signals for said adjacent pixel pseudo-windows;f) calculating at least first and second difference value signals, wherein said first difference value signal indicates a difference between said selected pixel pseudo-window gray level average value signal and a first adjacent pixel pseudo-window gray level average value signal, and said second difference value signal indicates a difference between said selected pixel pseudo-window gray level average value signal and a second adjacent pixel pseudo-window gray level average value signal;g) comparing said difference value signals to said threshold value signal; andh) assigning continuous tone output values to said pixels based upon said threshold value comparison.