Automatic exposure with digital gain optimized for noise reduction

摘要

A camera generally including a sensor and an auto-exposure circuit is disclosed. The sensor may be configured to generate a digital signal in response to an optical signal. The auto-exposure circuit may be configured to control a lightness of a picture within the digital signal by (i) adjusting at least one among an aperture, a shutter and an analog gain and (ii) adjusting a digital gain applied to the digital signal, wherein the digital gain adaptively reduces the lightness of the picture.

主权项

1. A camera comprising:
a sensor configured to generate a digital signal in response to an optical signal; and an auto-exposure circuit configured to control a lightness of a picture within said digital signal by (i) adjusting at least one of an aperture and a shutter to achieve a first mode in which said lightness of said picture is greater than an intended level, (ii) adjusting at least one of said aperture and said shutter to achieve a second mode in which said lightness of said picture is less than said intended level and (iii) adjusting a digital gain applied to said digital signal, wherein said digital gain adaptively (a) reduces said lightness of said picture by a negative decibel amount while in said first mode and (b) increases said lightness of said picture by a positive decibel amount while in said second mode.