Scanner and calibration method used therein

Abstract

A scanner and calibration method use therein. Setting first exposure duration and a second exposure duration for a transparency, wherein the first exposure duration is proportional to the second exposure duration. Scanning the transparency and a calibration area to produce a scan signal and a calibration signal, respectively, wherein the exposure duration for scanning the transparency is referred to as the first exposure duration, and the exposure duration for scanning the calibration area is referred to as the second exposure duration. Calculating a first gain coefficient according to the calibration signal. Calculating a second gain coefficient according to the first gain coefficient and a specific ratio of the first exposure duration to the second exposure duration, and finally, amplifying the scan signal by the second gain coefficient.

1 - 21 . (canceled)  
   
   
       22 . A calibration method for a scanner, comprising the following steps: 
 scanning a transparency according to a first exposure duration to obtain various image data;    converting the image data into various digital data, and analyzing the digital data to obtain a maximum digital value;    calculating a gain coefficient according to the maximum digital value, wherein the gain coefficient is a maximum gain coefficient for amplifying the image data to be converted into the digital data having the maximum digital value    calculating a second exposure duration by the product of the gain coefficient and the first exposure duration; and    scanning the transparency by the second exposure duration, to obtain an ideal scan signal.    
   
   
       23 . The calibration method as claimed in  claim 22 , wherein the maximum digital value is 255.  
   
   
       24 . The calibration method as claimed in claim  21 , the transparency is a positive film or a negative film.