Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-07-15
2001-07-10
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S475000, C358S486000, C358S487000
Reexamination Certificate
active
06259540
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to a distinguishing method for an object sensed by an optical device, and more particularly to a distinguishing method for an object scanned by a transmissive/reflective scanning device.
BACKGROUND OF THE INVENTION
At the present time, the scanners are so popular that they are required to have more and more functions. The flatbed scanner used today has both transmissive mode and reflective mode, and so does the sheetfed scanner. When a reflective object such as a piece of paper needs to be scanned, the reflective mode must be adopted. The light source (hereafter called “reflecting light source”) mounted at the same side of the charge coupled device is used to scan the reflective object. A reflected image signal is sensed by the photo sensor on the charge coupled device to be converted to digital data. When a transmissive object such as a transparency needs to be scanned, the transmissive mode, rather than the reflective mode, must be adopted. The light source (hereafter called “transmitting light source”) mounted at the opposite side of the charge coupled device is used to scan the transmissive object. A transmitted image signal is sensed by the charge coupled device to be converted to digital data. If the scanning mode is selected incorrectly, the image gotten at last will be ambiguous. The trouble of using the scanner is that the users must know the type of the scanned object and switch among the reflective mode and the transmissive mode of the scanner by themselves. The users are often puzzled by such manual operation when a great number of non-arranged documents including both types of the scanned objects need to be scanned. Apparently, it is inconvenient for the users to switch the scanning mode of the conventional scanner.
SUMMARY OF THE INVENTION
An objective of the present invention is to provide an method for automatically distinguishing the object scanned by a scanner.
In accordance with the present invention, a method is provided for distinguishing an object between a transmissive object and a reflective object used in a transmissive/reflective scanning device having a transmitting light source and a reflecting light source. The method includes steps of (a) turning on a first light source, (b) scanning a first portion of the object to obtain a first image signal by using the first light source, (c) calculating a first scanning value of the first image signal, (d) turning off the first light source and turning on a second light source, (e) scanning a second portion of the object to obtain a second image signal by using the second light source, (f) calculating a second scanning value of the second image signal, and (g) comparing the scanning values to distinguish the object to be one of the transmissive object and the reflective object.
In accordance with another aspect of the present invention, the step (b) further includes a step of (b1) feeding the first portion of the object into the scanning device.
In accordance with another aspect of the present invention, the first portion of the object is preferably the second portion of the object.
In accordance with another aspect of the present invention, before the step (e), the method further includes a step of (e1) withdrawing the first portion of the object from the scanning device. The step (e) further includes a step of (e2) feeding the second portion of the object into the scanning device.
In accordance with another aspect of the present invention, the step (b) preferably includes a step of (b2) detecting a width of the object. The object is preferably a rectangular object.
In accordance with another aspect of the present invention, the first scanning value and the second scanning value are preferably a first average gray scale and a second average gray scale respectively.
In accordance with another aspect of the present invention, the step (c) further includes the steps of (c1) summing up gray scale values of all pixels of the first image signal to get a first sum, and (c2) dividing the first sum by the number of pixels of the first image signal to get the first average gray scale. Likewise, the step (f) further includes the steps of (f1) summing up gray scale values of all pixels of the second image signal to get a second sum, and (f2) dividing the second sum by the number of pixels of the second image signal to get the second average gray scale.
In accordance with another aspect of the present invention, the first light source and the second light source are the transmitting light source and the reflecting light source respectively.
In accordance with another aspect of the present invention, the object is distinguished to be the transmissive object when the first average gray scale is bigger than the second average gray scale. On the contrary, the object is distinguished to be the reflective object when the first average gray scale is no bigger than the second average gray scale.
In accordance with another aspect of the present invention, the object can be distinguished by comparing a specific value with a ratio of the first average gray scale to the second average gray scale. If the ratio is bigger than the specific value, the object is distinguished to be the transmissive object. Otherwise, if the ratio is no bigger than the specific value, the object is distinguished to be the reflective object.
In accordance with another aspect of the present invention, the first light source and the second light source are the reflecting light source and the transmitting light source respectively.
In accordance with another aspect of the present invention, the object is distinguished to be the transmissive object when the first average gray scale is smaller than the second average gray scale. On the contrary, the object is distinguished to be the reflective object when the first average gray scale is no smaller than the second average gray scale.
In accordance with another aspect of the present invention, the object can be distinguished by comparing a specific value with a ratio of the first average gray scale to the second average gray scale. If the ratio is smaller than the specific value, the object is distinguished to be the transmissive object. Otherwise, if the ratio is no smaller than the specific value, the object is distinguished to be the reflective object.
The present invention may best be understood through the following description with reference to the accompanying drawing, in which:
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Fan Ching-Chih
Hsu Adolf T. R.
Lee Cheukfan
Mustek Systems Inc.
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