Patent ID: 8115859

Claim:
An auto-exposure control method comprising: creating an exposure table and an analog gain table including an exposure time and an analog gain of an image sensor set according to an index, respectively; calculating an average luminance value of an image frame obtained by the image sensor; checking whether or not the average luminance value is within a pre-set range including a prescribed final target value; if the average luminance value is not within the pre-set range, determining a shift step from indexes which have been applied to a current image frame according to the difference between the average luminance value and the final target value in order to determine indexes of the exposure table and the analog gain table to be applied to a next image frame; and repeatedly performing of reading an exposure time and an analog gain corresponding to the indexes shifted by the shift step determined from the indexes applied to the current image frame, from the exposure table and the analog gain table, applying the same to the image sensor, obtaining a next image frame, and calculating an average luminance value if the average luminance value is within the pre-set range, determining whether or not the average luminance value is substantially the same as the final target value; if the average luminance value is not the same as the final target value, determining the indexes of the exposure table and the analog gain table to be applied to the next image frame as neighbor indexes of the indexes which have been applied to the current image frame; proceeding to read an exposure time and analog gain corresponding to the determined neighbor indexes from the exposure table and the analog gain table, apply the same to the image sensor, obtain a next image frame, calculate an average luminance value of the obtained next image frame, and determine whether or not the average luminance value is substantially same as the final target value; and if the average luminance value is substantially the same as the final target value, terminating the auto-exposure controlling operation.