Dynamic range - A/D conversion

 dynamic range a/d conversion analog iccd camera

High speed image intensified CCD cameras equipped with analog video output.

Dynamic range of analog video units

Stanford Computer Optics high speed cameras with analog video units transfer the video signal analog in real-time to a frame grabber card in the PC. The A/D conversion is performed on the frame grabber card with a typically 10 bit resolution. Nevertheless, our non-linear gamma-processing technique allows a virtually 16 bit resolution limit anyhow.

The gamma-processing first compresses the analog value in the camera electronics to a root-function, that is analoguous transmitted to the frame grabber card in the PC. The frame grabber digitizes the compressed signal by a 10 bit A/D conversion. This yields a non-linear digital signal with quantization steps depending on the bit number of the resulting data word: the higher the bit number, the larger the quantization step related to the original analog signal.

This non-linearly coded signal is then decompressed in the PC by means of a high precision look-up table. The result is a linear-coded data word with a virtual resolution of 14 to 16 bit related to the cameras original analog signal.

Please note: The dynamic range of a high resolution CCD sensor pixel is about 214, i.e. 14 bit. 

Image intensified CCD cameras equipped with digital video output

Our digital video units include 14 bit A/D converters that keep the 14 bit dynamic range of the high resolution CCD chips.

You can find more revealing information about the A/D conversion in the following sections regarding the photon noise, and dynamic range expansion.

Please note: Each Stanford Computer Optics ICCD camera system serially comes with the Dynamic Range Expansion system which digitally enhances the real resolution up to 32 bit, independent of the type of video unit.