1. Field of the Invention
The present invention relates to image scanning methods, and more particularly, to an image scanning method that increases the probability of a quality scan.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram of a prior art scanner 10. The scanner 10 has a light source 12 for illuminating a document 14 to be scanned, a transparent panel 16 for supporting the document 14, and a scanning module 18 for scanning light from the document 14 to generate an image signal of the document 14. When performing a scan, the light source 12 and the scanning module 18 move simultaneously to scan the document 14.
As shown in FIG. 1, the scanning module 18 has a light sensor module 20 for converting light from the light source 12 to digital image signals. The light sensor module 20 has a lens 22 and a charge coupled device (CCD) 24. Light is directed to the light sensor module 20 by three light guides 26.
A common problem is scratches or dust on one, or more, of the light guides 26, which leads to poor scan quality, examples including, but not limited to, shadows or stripes on the output image.
It is therefore a primary objective of the present invention to provide a method of image scanning that increases the probability of a quality scan.
In a preferred embodiment, the present invention provides a method of image scanning used in a scanner. The scanner comprises a light source for illuminating a document to be scanned, and a scanning module for scanning the document. The scanning module comprises a light sensor module for receiving light from the document and generating an image signal of the document, and a light delivery module for delivering the light to the light sensor module. The light sensor module is capable of moving in a single direction, and it may be positioned on at least a first and second position. The method comprises:
At the first position, using the light source and the scanning module to obtain a first reference image signal by scanning a reference picture;
at the second position, using the light source and the scanning module to obtain a second reference image signal by scanning a reference picture;
according to the first and second reference image signals, positioning the light sensor module on either the first position or the second position; and
scanning the document;
wherein if flawed areas in the first reference image signal are fewer than flawed areas in the second reference image signal, the light sensor module is positioned on the first position to scan the document, and if flawed areas on the second reference image signal are fewer than flawed areas on the first reference image signal, the light sensor module is positioned on the second position to scan the document.
It is an advantage of the present invention that the probability of a quality scan is increased.
These and other objectives and advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.