Image processing apparatus and method allowing control of degree of edge enhancement
First Claim
Patent Images
1. An image processing apparatus, comprising:
- an input unit successively inputting a first image signal representing density level of each pixel;
a thresholding unit generating a second image signal by comparing the first image signal input from said input unit with a threshold value;
a calculating unit calculating, based on the second image signal generated by said thresholding unit and the threshold value used for generating the second image signal, a threshold value to be used for thresholding a succeeding pixel; and
a changing unit for enlarging or reducing at least one of a range of the first image signal input from said input unit and range of the threshold value calculated by said calculating unit.
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Abstract
An image forming apparatus capable of solving problems experienced in the error diffusion method operates in the following manner. An input pixel value is thresholded by a corrected threshold value, and a binarized pixel value is output. From the output value, the corrected threshold value is subtracted, the result is multiplied by a feedback coefficient β, and the result is diffused to the threshold values of surrounding pixels. As the threshold value and a scale of the pixel value are changed by the processing unit before thresholding, degree of edge enhancement is controlled.
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Citations
15 Claims
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1. An image processing apparatus, comprising:
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an input unit successively inputting a first image signal representing density level of each pixel; a thresholding unit generating a second image signal by comparing the first image signal input from said input unit with a threshold value; a calculating unit calculating, based on the second image signal generated by said thresholding unit and the threshold value used for generating the second image signal, a threshold value to be used for thresholding a succeeding pixel; and a changing unit for enlarging or reducing at least one of a range of the first image signal input from said input unit and range of the threshold value calculated by said calculating unit. - View Dependent Claims (2, 3, 4, 5)
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6. A method of image processing, comprising:
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an input step of successively inputting a first image signal representing density level of each pixel; a thresholding step of generating a second image signal by comparing the first image signal input in said input step with a threshold value; a calculating step of calculating, based on the second image signal generated in said thresholding step and the threshold value used for generating the second image signal, a threshold value to be used for thresholding of a succeeding pixel; and a changing step of enlarging or reducing at least one of a range of the first image signal input in said input step and a range of the threshold value calculated in said calculating step.
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7. An image processing apparatus, comprising:
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an input unit successively inputting a first image signal representing density level of each pixel; a thresholding unit generating a second image signal by comparing the first image signal input from the input unit with a threshold value; a calculating unit calculating, based on the second image signal generated by said thresholding unit and the threshold value used for generating the second image signal, a threshold value to be used for thresholding a succeeding pixel; and a changing unit changing ratio of a range of the first image signal input from said input unit and a range of the threshold value calculated by said calculating means.
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8. An image processing apparatus comprising:
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an input unit successively inputting a first image signal representing density level of each pixel; a thresholding unit generating a second image signal by comparing the first image signal input from said input unit with a threshold value; and a calculating unit calculating, based on said first image signal, said second image signal and the threshold value used for generating said second image signal, a threshold value to be used for thresholding a succeeding pixel; wherein said calculating means calculates the threshold value using difference between said second image signal and the threshold value used for generating said second image signal and difference between said first image signal and said second image signal, as parameters. - View Dependent Claims (9, 10)
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11. An image processing apparatus comprising:
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an input unit successively inputting a first image signal representing density level of each pixel; a thresholding unit generating a second image signal by comparing the first image signal input from said input unit with a threshold value; a calculating unit calculating, based on said first image signal, said second image signal and the threshold value used for generating said second image signal, a threshold value to be used for thresholding a succeeding pixel; a first multiplying unit multiplying the first image signal input to said thresholding unit by a prescribed first coefficient, and a second multiplying unit multiplying the first image signal input to said calculating unit by a prescribed second coefficient. - View Dependent Claims (12)
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13. An image processing apparatus, comprising:
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an input unit successively inputting a first image signal representing density level of each pixel; first multiplying unit multiplying said input first image signal by a prescribed first coefficient; a second multiplying unit multiplying said input first image signal by a prescribed second coefficient; a thresholding unit generating a second image signal by comparing an output of said first multiplying unit with a threshold value including an output of said second multiplying unit; and a calculating unit calculating, based on the second image signal generated by said thresholding unit and a threshold value used for generating the second image signal, a threshold value to be used for thresholding a succeeding pixel. - View Dependent Claims (14, 15)
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Specification