Image signal processing method and apparatus
First Claim
1. A method of processing image pixels line by line to enhance distinctions between halftone and text images, comprising the steps of:
- (a) performing an initial distinction between halftone and text images by addressing a memory having predetermined halftone and text relationships stored therein with successive groups of said image pixels to provide halftone and text signals;
(b) generating a count signal in accordance with said halftone and text signals for each group of image pixels;
(c) providing a preset count in response to said count signal for each group of image pixels;
(d) summing a predetermined number of said preset counts to provide a total count;
(e) comparing said total count with a predetermined fixed threshold to provide an enhanced control signal identifying the presence of either halftone or text images; and
(f) operating an image generator to output halftone or text image signals in response to said enhanced control signal.
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Accused Products
Abstract
A two stage image processing apparatus and method wherein, in a first stage, successive groups of image pixels are used to address a RAM based look up table to provide a preliminary breakdown between halftone and textural images. As a second stage, to further enhance the differentiation between halftone and textural images, the output of the RAM address table is employed to generate a count signal. Previous counts stored in a succession of counters are used to determine a new count, a predetermined number of which are summed as a block by an adder in response to the count signal. The is compared with a preset threshold to generate a control signal for operating a pixel generator. The new counts are used to update the counters, the count on the counter serving to represent prior pixel processing conditions.
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Citations
11 Claims
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1. A method of processing image pixels line by line to enhance distinctions between halftone and text images, comprising the steps of:
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(a) performing an initial distinction between halftone and text images by addressing a memory having predetermined halftone and text relationships stored therein with successive groups of said image pixels to provide halftone and text signals; (b) generating a count signal in accordance with said halftone and text signals for each group of image pixels; (c) providing a preset count in response to said count signal for each group of image pixels; (d) summing a predetermined number of said preset counts to provide a total count; (e) comparing said total count with a predetermined fixed threshold to provide an enhanced control signal identifying the presence of either halftone or text images; and (f) operating an image generator to output halftone or text image signals in response to said enhanced control signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. Apparatus for processing image pixels to enhance the distinctions between halftone and text images comprising in combination:
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memory means for storing discrete halftone and text image signals at predetermined addresses; addressing means for addressing said memory means using a preset combination of successive image pixels to provide halftone and text identifying signals; a plurality of scanline counters; a counter actuating means for changing the current count on said counters in response to said halftone and text signals output by said memory means; a plurality of adders, there being one adder associated with each of a preset number of said counters; means for successively processing the count on each of said counters to provide a predetermined count; means for loading the adder associated with said counter with said predetermined counts; means for deriving a halftone or text signal from the output of said adders; and means for generating halftone or text pixels in response to said halftone and text signals. - View Dependent Claims (8, 9, 10, 11)
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Specification