Image scanner having brightness compensation function via output adjustment

A method for compensating an image sense signal obtained from an image scanner, comprising the steps of:

• (a) providing an object to be scanned and a brightness reflection device;
• (b) causing to be generated an image sense signal obtained from said object and a reference brightness signal obtained from said brightness reflection device in response to a light signal;
• (c) digitizing said image sense signal and said reference brightness signal;
• (d) comparing a color scale value of said digitized reference brightness signal with a predetermined color scale value to obtain a compensating color scale value for said digitized image sense signal;
• and
• (e) compensating said digitized image sense signal by numerically operating between said compensating color scale value and said color scale value of said digitized image sense signal.

An image scanner for scanning a scanned object, comprising:

• a linear bottom scanning window for defining a scan line for said scanned object;
• a piece of brightness reflection device attached on said linear bottom scanning window;
• a light source for illuminating a light on said bottom scanning window to generate a scan line image signal including an image of said scan line of said scanned object and an image of said piece of said brightness reflection device;
• a linear image sensor for receiving said scan line image signal and respectively generating an image sense signal and a reference brightness reflection signal;
• and
• a brightness-controlling device electrically connected to said linear image sensor for converting said image sense signal and said reference brightness signal into digitized signals and then mathematically adjusting said digitized image sense signal according to said digitized reference brightness signal.