| 摘要 |
An image processing apparatus for charge coupled device (CCD) and video inputs in a digital camera or for a digital camcorder is disclosed which provides optical black and offset correction for CCD inputs. A sampling circuit, including correlated double sampler (CDS) (402) and programmable gain amplifier (450), samples the image input signal and the video input signal. CDS (402) includes a single-ended amplifier (404) and a differential amplifier (406). The single-ended amplifier (404) functions such that it is only operable during an CCD signal input; otherwise, the single-ended amplifier (404) is bypassed such that a video signal is only sampled by the differential amplifier (406). For CCD signals, the single-ended amplifier (404) samples the reference level of the pixel and holds it during the video interval. The differential amplifier (404) samples both the output of the single ended amplifier (404) and the video level of the same pixel. Overall, the CDS (402) subtracts these levels and converts the difference to a differential output to improve signal to noise performance and dynamic range. An analog-to-digital converter (210) converts the sampled signal and feeds this digital sample to a digital correction circuit (212-238) where optical black level, hot and cold pixels, and line noise are removed.
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