In advanced conventional light collection technologies, such as those used for telescope applications in space, it is often beneficial to utilize a large sensor array with a large number of pixels. For instance, the HgCdTe Astronomy Wide Area Infrared Imager with 2K×2K Resolution, Reference Pixels and Guide Mode (“H2RG™”-trademark of Teledyne Imaging Sensors) sensor reads out from approximately four million sensor pixels and multiplexes the readout to 1, 2, 4, 8, 16, or 32 output channels. Such sensors may be capable of detecting low level photon emissions that are outside of the visible light spectrum, such as near-infrared (“NIR”), which has wavelengths varying from slightly less than 1 micrometer up to approximately 5 micrometers.
In addition to the measured (or “hot”) pixels that detect a phenomenon of interest photon emissions, such sensor arrays generally include non-illuminated reference pixels that do not actually register radiation that is illuminating the array. These reference pixels are a type of noise correction technology for the digital domain, in addition to a single analog reference pixel that is generally subtracted from all hot pixels of the sensor array on the sensor. The reference pixels are read out and digitized with hot pixels as a single frame. Rather than trying to prevent noise from occurring by improving the quality of sensor components, an approach that is limited by physics and may be cost-prohibitive, scientists and engineers frequently seek to correct data after the analog signal has been sampled and converted from analog to digital signals (i.e., when data is in the digital domain). Further, while most types of noise can be corrected for at the analog level, certain types of noise, such as thermal noise, are difficult to compensate for. For instance, thermal noise, which is the random motion of electrons inherent in all objects at a temperature above absolute zero, is extremely difficult to compensate for without engaging in expensive cryogenic procedures. Such types of noise are best corrected in the digital domain.
In conventional averaging of reference pixel magnitudes in the digital domain, the fast-varying noise components may be modeled by sinusoids varying around zero. However, these fast-varying noise components drop out from noise calculations and remain hidden in the readout data. Accordingly, improved noise correction techniques in the digital domain may be beneficial.
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