Scanning system having brightness compensation apparatus and method thereof

A scanning system having a brightness compensation mechanism for scanning a plurality of pages, the scanning system comprising:

• a light source, for generating a brightness to illuminate the pages;
• an image sensor, for sensing image data shown on the pages in order to output analog signal data corresponding to the image data;
• an analog-front-end coupled to the image sensor, for converting the analog signal data into digital signal data;
• a brightness compensation apparatus coupled to the analog-front-end, the brightness compensation apparatus comprising:
• an image processing apparatus, for processing the digital signal data, for generating current brightness statistic data of a current page based on the statistic window setting region, and for comparing the brightness statistic data with a brightness target value for adjusting brightness of the scanning system according to the compared result between the brightness statistic data and the brightness target value;
• and
• a first voltage control circuit coupled to the image processing apparatus, for outputting a voltage-adjusting signal for adjusting the brightness;
• a second voltage control circuit coupled to the first voltage control circuit, for outputting a direct-current (DC) voltage;
• and
• an inverter coupled to the second voltage control circuit, for receiving the DC voltage and outputting an alternating current (AC) voltage with high level in order to control the brightness by at least one level of the DC voltage.