Digital black clamp circuit in electronic imaging systems

Details Digital black clamp circuit in electronic imaging systems Digital black clamp circuit in electronic imaging systems

2007-08-21

2007-08-21

Vu, Ngoc-Yen (Department: 2622)

Television

Camera, system and detail

Combined image signal generator and general image signal...

Reexamination Certificate

active

10400783

ABSTRACT:
The present invention is a black clamp circuit for an electronic imager having black reference pixels. The circuit includes an average value circuit determining an average of a number of the black reference pixels, a correction circuit determining the black level correction from the average, and a modifier circuit modifying image pixels with the black level. The average value is used in a real time feedback loop that removes offset errors in the signal processing chain and establishes a corrected black level in output image data. The feedback can be either digital or analog. The correction circuit can include a comparator that allows a hysteresis in the feedback to avoid hunting as well as multiple levels of feedback based on several thresholds. The corrected black level can also be controlled by a digital transfer function. The black clamp circuit can be used for a series of images, an image frame and an image line.

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