Patent ID: 6784939
Filing Date: 2004-08-31
Classification: H04N

Abstract:
A method for automatically controlling an exposure time in a CMOS image sensor, wherein the image sensor includes a pixel array, the method comprising the steps of:a) producing a total pixel value only for a number of the green pixels from the pixel array; b) producing a mean value of the green pixels by dividing the total pixel value of the green pixels by the number of the green pixels; c) producing a deviation value, wherein the deviation value is an absolute value of a difference between the mean value of the green pixels and a predetermined reference value; d) comparing the deviation value with a predetermined boundary value; e) in case where the deviation value is smaller than the predetermined boundary value, capturing a next image according to a current exposure time, and in case where the deviation value is larger than the predetermined boundary value, calculating an exposure control rate and determining whether an automatic exposure control mode is enabled, said exposure control rate being calculated instead of performing the steps of a) and b) in a first line and a last line of the pixel array; and f) in case where the automatic exposure control mode is disabled, capturing the next image according to the current exposure time, and in case where the automatic exposure control mode is enabled, capturing the next image according to a next exposure time, wherein the next exposure time is calculated by multiplying the current exposure time by the exposure control rate.