Patent ID: 6859230

Claim:
A method of automatically controlling the exposure time of an image sensor, said image sensor including a matrix of pixels, said method comprising: determining a value NW as the number of pixels in said matrix that output a pixel signal greater than a value VHIGH; determining a value NB as the number of pixels in said matrix that output a pixel signal less than a value VLOW; determining a value NVW as the number of pixels in said matrix that output a pixel signal greater than a value VSHIGH; determining a value NVB as the number of pixels in said matrix that output a pixel signal less than a value VSLOW; determining if NW is greater than a first predetermined high threshold KW, and if so: determining if NVW is greater than a second predetermined high threshold KVW, and if so, decreasing said exposure time by a first decrease percentage P 1 , but if not, decreasing said exposure time by a second decrease percentage P 2 ; and determining if NB is greater than a first predetermined low threshold KB, and if so: determining if NVB is greater than a second predetermined low threshold KVB, and if so, increasing said exposure time by a first increase percentage P 3 , but if not, increasing said exposure time by a second increase percentage P 4 .