Automatic multimode continuous halftone line copy reproduction

The method of automatically processing unknown image pixels, the steps comprising:

• (a) identifying high frequency half-tone image pixels in said image pixels;
• (b) identifying continuous tone image pixels in said image data;
• (c) identifying low frequency half-tone and line pixels in said image pixels;
• (d) descreening any image pixels found in step a;
• (e) screening any image pixels produced by steps b or d;
• and
• (f) thresholding any image pixels found in step c.

In the method of processing image data in the form of pixels to provide binary level output pixels, the steps which comprise:

• (a) identifying continuous tone or high frequency half-tone pixels in said image data;
• (b) descreening said high frequency half-tone pixels to provide descreened high frequency half-tone pixels;
• (c) screening said continuous tone and said descreened high frequency half-tone pixels to provide said binary level output pixels;
• and
• (d) thresholding the remaining pixels in said image data to convert said remaining pixels to binary level output pixels.

In an apparatus for processing a stream of image data, said image data being in the form of pixels whose signal levels represent the intensity of the discrete image areas represented by each pixel, the combination comprising:

• (a) image data identifying means for identifying high frequency half-tone and continuous tone pixels in said stream of image data;
• (b) descreen means for descreening any high frequency half-tone pixels found;
• (c) screen means for screening any continuous tone and descreened high frequency half-tone pixels found;
• and
• (d) threshold means for thresholding pixels remaining in said image data stream.

In an apparatus for processing image data, said image data being in the form of a stream of image pixels whose signal levels represent the intensity of the discrete image areas represented by each pixel, the combination comprising:

• (a) means for producing a first control signal in response to the presence of high frequency half-tone image pixels in said pixel stream, a second control signal in response to the presence of continuous tone image pixels in said pixel stream, and a third control signal in response to the presence of low frequency half-tone and line copy image pixels in said pixel stream;
• (b) first image data processing means for processing high frequency half-tone image pixels;
• (c) second image data processing means for processing continuous tone image pixels;
• (d) third image data processing means for processing low frequency half-tone and line copy image pixels;
• and
• (e) control means responsive to said first, second and third control signals for actuating said first, second and third image data processing means respectively whereof to process said image data regardless of the pixel content of said image data.

In an apparatus for processing image pixels which may represent continuous tone images, high frequency halftone images, low frequency halftone images, and/or line images, the combination of:

• (a) descreening means for descreening high frequency halftone image pixels;
• (b) screening means coupled to said descreening means output for rescreening descreened high frequency halftone image pixels output from said descreening means;
• (c) thresholding means for thresholding low frequency halftone and line image pixels;
• and
• (d) bypass means effective when actuated to bypass said descreening means to permit continuous tone image pixels to be routed directly to said screening means.