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US 5,473,444 AGranted
Image processing device having function of detecting dotted-image area
AssigneeRicoh Company, Ltd.
InventorsYukio Sakano, Hiromi Okubo
Life of this patent
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Abstract
An image processing device includes a first unit for detecting a pixel at which a predetermined local variation of image data occurs, a second unit for detecting a density relating to the above pixel within a predetermined scanning area, and a third unit for determining whether or not the image data forms a dotted-image area on the basis of the density detected by the second unit.
Claims6
An image processing apparatus, comprising:
- a) variation point detecting means for detecting when pixels vary so that both conditions 1 and 2 are met:
- 1) density differences between neighboring pixels change in the following order:
- i) a first value representing a first density difference computed between a first pair of neighboring pixels which are encountered first;
- ii) a second value representing a second density difference computed between a second pair of neighboring pixels which are encountered second, after the first pair of neighboring pixels;
- and
- iii) a third value representing a third density difference computed between a third pair of neighboring pixels which are encountered third, after the second pair of neighboring pixels;
- and
- 2) the second value representing the second density difference is greater than both the first value representing the first density difference and the third value representing the third density difference;
- b) density detecting means for detecting, as a dotted-image area, an arrangement in which the pixels, which are detected by the variation point detecting means, are spaced apart from each other at an interval which is less than or equal to a predetermined number of pixels;
- and
- c) smoothing processing means for performing a smoothing operation on densities of the pixels having the arrangement detected by the density detecting means.
8 more elements
An image processing method comprising:
- a) detecting when pixels vary so that both conditions 1 and 2 are met:
- 1) density differences between neighboring pixels change in the following order:
- i) a first value representing a first density difference computed between a first pair of neighboring pixels which are encountered first;
- ii) a second value representing a second density difference computed between a second pair of neighboring pixels which are encountered second, after the first pair of neighboring pixels;
- and
- iii) a third value representing a third density difference computed between a third pair of neighboring pixels which are encountered third, after the second pair of neighboring pixels;
- and
- 2) the second value representing the second density difference is greater than both the first value representing the first density difference and the third value representing the third density difference;
- b) detecting, as a dotted-image area, an arrangement in which the pixels, which are detected by the detecting step a), are spaced apart from each other at an interval which is less than or equal to a predetermined number of pixels;
- and
- c) performing a smoothing operation on densities of the pixels having the arrangement detected by the density detecting means.
8 more elements
Dependencies are inferred from the claim text.