Multichannel Imaging Principles

Key Takeaways

Understand 400–700 nm, 15 spectral channels, FWHM, a 4 × 4 CFA, calibration, and demosaicing.

Visible Wavelength Range

Visible light is commonly described as approximately 400–700 nm. Filter responses let a sensor sample different bands; real responses may overlap rather than form ideal rectangular windows.

What Is a Spectral Channel?

A spectral channel represents sensor response over a wavelength band. Channel count describes spectral dimensions, not spatial pixels, and does not mean every channel has full native resolution.

What 15 Channels Mean

Fifteen channels provide more spectral sampling dimensions than RGB. The reference SVGA 864 × 648 describes the spatial image format; after 4 × 4 CFA reconstruction, per-channel sampling depends on the filter pattern and algorithm. Do not claim a full independent 864 × 648 for every channel.

FWHM and Channel Bandwidth

FWHM (full width at half maximum) measures the width of a response peak at half its maximum. An average near 34 nm summarizes bandwidth; individual response shapes and widths may differ.

4 × 4 CFA, Calibration, and Demosaicing

A 4 × 4 CFA distributes spectral filters in a mosaic. Demosaicing uses neighboring samples to reconstruct multi-channel images. Factory calibration factors are stored in a 64-kbit on-module EEPROM and should be applied in processing. Results still depend on illumination, optics, and algorithms.

Analyzing Multispectral Data

Algorithms can derive spectral features, classification, or detection from corrected multi-channel data. Record capture conditions, calibration version, and processing parameters, and validate on representative data. Channel count alone does not establish accuracy.

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