IMAGE PROCESSING APPARATUS AND METHOD THEREOF
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Abstract
When a halftone dot region includes a character or line drawing, high extraction performance of a halftone dot region cannot be obtained. Hence, the isolation amount of an interest pixel is calculated, and the isolation amounts are integrated in a plurality of areas having different sizes. Thresholds set for respective areas are compared with the integration result to determine whether or not the interest pixel belongs to a halftone dot region.
24 Citations
15 Claims
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1-9. -9. (canceled)
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10. A method of extracting image regions from an image including different types of image regions, comprising:
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using a processor to perform the steps of; generating an edge-emphasized image by applying an edge-emphasis process to an input image; setting an inner edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel greater than a first threshold value, and setting an outer edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel less than a second threshold value, wherein the first threshold value is positive and the second threshold value is negative; determining whether an OR signal of each pixel is set to an affirmative value or not based on the inner and outer edge signals of each pixel; counting a first number of pixels having the affirmative OR signal in an area which includes a pixel of interest and has a first pixel size so as to compare the counted first number with a third threshold value; counting a second number of pixels having the affirmative OR signal in an area which includes the pixel of interest and has a second pixel size larger than the first pixel size so as to compare the counted second number with a fourth threshold value; and determining whether or not the pixel of interest belongs to a halftone dot region based on the comparison results in the first and second counting steps. - View Dependent Claims (11, 12, 13)
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14. An image processing apparatus for extracting image regions from an image including different types of image regions, comprising:
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a generator configured to generate an edge-emphasized image by applying an edge-emphasis process to an input image; a setter configured to set an inner edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel greater than a first threshold value, and to set an outer edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel less than a second threshold value, wherein the first threshold value is positive and the second threshold value is negative; a first determiner configured to determine whether an OR signal of each pixel is set to an affirmative value or not based on the inner and outer edge signals of each pixel; a first comparator configured to count a first number of pixels having the affirmative OR signal in an area which includes a pixel of interest and has a first pixel size so as to compare the counted first number with a third threshold value; a second comparator configured to count a second number of pixels having the affirmative OR signal in an area which includes the pixel of interest and has a second pixel size larger than the first pixel size so as to compare the counted second number with a fourth threshold value; and a second determiner configured to determine whether or not the pixel of interest belongs to a halftone dot region based on the comparison results of the first and second comparators.
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15. A computer-readable storage medium storing a computer-executable program for causing a computer to perform a method of extracting image regions from an image including different types of image regions, the method comprising the steps of:
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generating an edge-emphasized image by applying an edge-emphasis process to an input image; setting an inner edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel greater than a first threshold value, and setting an outer edge signal of a pixel of the edge-emphasized image to an affirmative value when a value of the pixel less than a second threshold value, wherein the first threshold value is positive and the second threshold value is negative; determining whether an OR signal of each pixel is set to an affirmative value or not based on the inner and outer edge signals of each pixel; counting a first number of pixels having the affirmative OR signal in an area which includes a pixel of interest and has a first pixel size so as to compare the counted first number with a third threshold value; counting a second number of pixels having the affirmative OR signal in an area which includes the pixel of interest and has a second pixel size larger than the first pixel size so as to compare the counted second number with a fourth threshold value; and determining whether or not the pixel of interest belongs to a halftone dot region based on the comparison results in the first and second counting steps.
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Specification