Image processing apparatus and method allowing control of degree of edge enhancement
First Claim
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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.
15 Citations
17 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. - View Dependent Claims (9, 10, 11, 12, 13)
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14. 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; and
a calculating step of 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.
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15. 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 (16, 17)
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Specification