Image analysis – Image sensing – Multiple scanning
Reexamination Certificate
1999-01-28
2001-08-21
Au, Amelia M. (Department: 2721)
Image analysis
Image sensing
Multiple scanning
C382S299000, C358S406000, C358S497000
Reexamination Certificate
active
06278808
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for obtaining relative and absolute modifying factors in the first and the second directions, and especially to a method and an apparatus for obtaining the relative and absolute modifying factors in the transverse and the longitudinal directions for an image scanning apparatus.
BACKGROUND OF THE INVENTION
In recent years, an image scanner has become an indispensable peripheral equipment of personal computers. Many manufacturers are trying their best to improve the scanning quality.
In a scanner, the image-picking device including a series of lenses picks the image of an object in the transverse direction (or the horizontal direction). If the optical error of lens is ±1.0%, the magnification error in the transverse direction will be ±1.5%. Taking an A4 size document having a width of 210 mm for example, the scanned image will have a length error of 3.15 mm.
Furthermore, the driving device for driving the image-picking device also has a mechanical error in the moving direction of the image-picking device (or the longitudinal direction). For a scanner with a resolution of 600 dots per inch (DPI), the driving device will move the image-picking device 6000 steps for scanning a document with a length of 10 inches to obtain an image having 6000 dots in length. However, with a mechanical error of +1.0%, the driving device must move 6060 steps to finish the scanning process so that the length of the scanned image is up to 6060 dots, resulting in that the length of the scanned image is changed from 10 inches to 10.1 inches.
When the magnification errors in the transverse and longitudinal directions are not the same, the scanning image will be distorted. The magnification errors may come out after the scanner has used for a period of time or under the careless operation.
The main interest of the present invention is to provide an method and an apparatus for obtaining the relative and absolute modifying factors in the transverse and longitudinal directions for an image scanning apparatus. The method and apparatus can effectively correct the scanned image so as to improve the scanning quality.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a method for obtaining a relative modifying factor in the first and second directions for an image scanning apparatus so as to eliminate the distortion of scanned images.
The method includes the steps of (a) providing a line segment, which extends in a direction other than either one of the first and the second directions, having a plurality of scanning points wherein there is a specific functional relationship between a distance in the first direction of and a distance in the second direction of any two of the scanning points, (b) scanning the line segment at a first one of the scanning points, (c) scanning the line segment at a second one of the scanning points, wherein there is a particular position distance in the first direction between the first and the second scanning points, (d) obtaining a scanning distance between the first and the second scanning points in the second direction from the image scanning apparatus, and (e) calculating the relative modifying factor from the scanning distance and the particular position distance according to the specific functional relationship.
In accordance with one aspect of the present invention, the specific functional relationship is a slope and the line segment intersects with a moving path of an image-picking device. The first direction is a moving direction of the image-picking device driven by a driving device and the second direction is a direction perpendicular to the first direction. Alternatively, the first direction and the second direction are the longitudinal direction and the transverse direction respectively. The first direction and the second direction are in a plane which is a scanning platform for placing thereon an object to be scanned.
Another object of the present invention is to provide a method for simultaneously obtaining absolute modifying factors in the first and second directions for an image scanning apparatus. This method not only eliminates the distortion of scanned images but also insures that the size of the scanned image is exactly the same as that of the original object.
The method includes the steps of (a) providing a line segment, which extends in a direction other than either one of the first and the second directions, having a plurality of scanning points wherein there is a specific functional relationship between a distance in the first direction of and a distance in the second direction of any two of the scanning points, (b) scanning the line segment at a first one of the scanning points, (c) scanning the line segment at a second one of the scanning points, wherein there is a particular position distance in the first direction between the first and the second scanning points, (d) obtaining a scanning distance between the first and the second scanning points in the second direction from the image scanning apparatus, and (e) calculating the relative modifying factor from the scanning distance and the particular position distance according to the specific functional relationship.
After the step (e), the method further includes the steps of (f) scanning the trapezoid pattern at the upper base, (g) scanning the trapezoid pattern at the lower base, (h) obtaining a moving length between the upper base and the lower base in the first direction, (i) comparing the height with the moving length to obtain an absolute modifying error in the first direction, and k) obtaining absolute modifying factors in the first and the second directions simultaneously from the absolute modifying error and the relative modifying factor.
According to the above-mentioned embodiment, the image scanning apparatus further includes a trapezoid pattern with a first color and a background with a second color forming therebetween an oblique boundary line served as the line segment, wherein the trapezoid pattern has an upper base and a lower base which are parallel to the second direction, and has a height in the first direction. Preferably, the first color is black and the second color is white.
In another embodiment, the method for simultaneously obtaining absolute modifying factors in a first and a second directions for an image scanning apparatus includes the steps of (a) providing a first line segment, which extends in a direction other than either one of the first direction and the second direction, having a plurality of scanning points wherein there is a specific functional relationship between a distance in the first direction and a distance in the second direction of any two of the scanning points, (b) providing a second line segment having a particular length in the second direction, (c) scanning the first line segment at a first one of the scanning points, (d) scanning the first line segment at a second one of the scanning points, wherein the first and the second scanning points have a particular position distance in the first direction, (e) obtaining a scanning distance between the first and the second scanning points in the second direction from the image scanning apparatus, (f) scanning the second line segment to obtain a scanning length in the second direction, (g) comparing the particular length with the scanning length to obtain an absolute modifying error in the second direction, (h) calculating a relative modifying factor from the scanning distance and the particular position distance in the specific functional relationship, and (i) obtaining the absolute modifying factors in the first and the second directions simultaneously from the absolute modifying error and the relative modifying factor.
According to the above-mentioned method, the image scanning apparatus further includes a first marking pattern with a first color and a background with a second color forming therebetween an oblique line segment served as the first line segment and a second marking pattern hav
Chen Bill
Tsai Jenn-Tsair
Au Amelia M.
Dastouri Mehrdad
Mustek Systems Inc.
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