Patent Application
20050094168
1. Field of the Invention
The present invention relates to the scanning operation of an optical scanner and, more specifically to a fluorescent color scanning method used in a scanner to accurately scan documents containing fluorescent substances.
2. Description of the Related Art
Following fast development of computer technology, the trend of office automation keeps going forward. To achieve office automation, it is necessary to scan paper documents into electronic files for transmission by E-mail through a network.
Because of the attractively bright-colored feature, fluorescent substance is intensively used in a variety of documents, for example, used in ink for color printer, paper, and fluorescent markers. However, because the radiance factor of regular commercialized fluorescence is over 1 under visible spectrum, it is difficult to accurately obtain the original fluorescent color by means of conventional scanning methods.
The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a fluorescent color scanning method, which eliminates color distortion. It is another object of the present invention to provide a fluorescent color scanning method, which accurately judges the presence of a fluorescent color in the document. It is still another object of the present invention to provide a color conversion method, which enables the scanner to produce accurate color output.
To achieve these and other objects of the present invention, the fluorescent color scanning method comprises the steps of: (a) using a light source of a predetermined brightness to scan a standard white so as to obtain a first reference white W1(R,G,B) in which R indicates red color; G indicates green color; B indicates blue color; (b) reducing the brightness of said light source, and then scanning said standard white to obtain a second reference white W2(R,G,B); (c) using said first reference white W1(R,G,B) as the standard to scan every scanning point and then storing the scanned result of each scanning point by means of Pm(R,G,B), in which m=1, 2, 3 . . . , m that represents the respective scanning point; (d) using said second reference white W2(R,G,B) as the standard to scan every scanning point of the document to be scanned and then storing the scanned result of each scanning point by means of Qm(R,G,B); and (e) comparing the value of W2(R,G,B) to the value of Qm(R,G,B), so as to determine if the document contains a fluorescent color or not subject to: (i) determining that the document contains a fluorescent color if Qm(R)>W2(R), Qm(G)>W2(G), or Qm(B)>W2(B), and then converting said Qm(R,G,B) into the accurate color output Om(R,G,B) based on said W1(R,G,B) through a conversion method, and (ii) determining that the document contains no fluorescent color if Qm(R)≦W2(R), Qm(G)≦W2(G), and Qm(B)≦W2(B), and then using the value of Pm(R,G,B) as the image output value.
The accompanying, drawing is included to provide a further understanding of the invention, and is incorporated in and constitutes a part of this specification. The drawing illustrates an embodiment of the invention and, together with the description, serves to explain the principles of the invention. In the drawing,
In order to have the scanner show accurate chroma and hue when scanning a fluorescent color, the invention detects the presence of a fluorescent color in document by means of reducing the scanning brightness. In case document contains a fluorescent color, the scanning result is converted through a proper conversion before output, so that the output image has the accurate color.
Referring to
In the aforesaid step S30, determining the presence of a fluorescent color in document is determined subject to the result of comparing Qm(R,G,B) to W2(R,G,B), i.e., document is confirmed containing a fluorescent color if Qm(R)>W2(R), Qm(G)>W2(G), or Qm(B)>W2(B). In this case, one color sensor is saturated: Therefore, the scanning result must be properly converted to provide the accurate chroma and hue before output. However, if Qm(R)≦W2(R), Qm(G)≦W2(G), and Qm(B)≦W2(B), it means no fluorescent color in document. In this case, proceed to step S36, i.e., Pm(R,B,G) is the accurate scanning result.
In the aforesaid step S32, the conversion is achieved by: setting the maximum value of Qm(R), Qm(G), and Qm(B) to be Bm and then calculation the ratio of each color Um(R,G,B) in which Um(R)=Qm(R)/Bm; Um(G)=Qm(G)/Bm; Um(B)=Qm(G)/Bm. Based on W1(R,G,B), obtain the accurate color tone and hue output value Om(R,G,B) in which; Om(R)=Um(R)*W1(R); Om(G)=Um(G)*W1(G); Om(B)=Um(B)*W1(B).
In the aforesaid method, fluorescent color scanning is achieved by means of the application of different brightness (light intensity). There are various methods to reduce scanning brightness. Hereinafter describes one example.
As indicated above, the method of the present invention enables the scanner to accurate scan fluorescent colors. By means of the present invention, it needs only to slightly change the architecture or control circuit of the original scanner. This minor architecture or control circuit change does not increase much cost while improving the scanning quality and increasing the added value of the scanner. Therefore, the invention has an industrial value.
A prototype of fluorescent color scanning method has been constructed with the features of FIGS. 2˜4. The fluorescent color scanning method functions smoothly to provide all of the features discussed earlier.
Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
