Detecting smear leakage in an image sensor exposed to a bright light source

Abstract

Smear detect circuitry within an analog front end (AFE) of a digital camera determines when black area pixel values received from an image sensor are indicative of smear leakage. Smear leakage can cause a light vertical line in the resulting digital image. When a sensor that is coupled to a storage element is exposed to a bright light source, storage element overload can cause a leakage charge to leak from the storage element to other storage elements along a transfer line. Smear detect circuitry identifies the transfer line exhibiting smear leakage and excludes pixel values from storage elements along that transfer line from the calculation of a black level value used to calibrate color pixel values. The digital camera displays a smear icon indicating smear leakage in a digital image that is to be taken. A digital file of the digital image includes a header with a smear detect field.