Digital Imaging with Multispectral Filter Array (MSFA) Sensors

Dear Colleagues,

Current digital imaging systems (including digital cameras) often comprise a monochrome image sensor with a color filter array (CFA) for capturing color information. Bayer CFA is based on the primary color channels (red, green, and blue), and has been widely applied in general digital imaging. Furthermore, various CFAs have been developed for overcoming the physical limitations of Bayer CFA. Multispectral filter array (MSFA) has been recently proposed, which can capture the three primary color channels and additional spectral bands, such as near-infrared and broadband. The MSFA design determines the manner in which multiple bands of light will be received, because digital imaging aspects, such as sensitivity, resolution, and color reproduction, significantly depend on the filter pattern. The MSFA image sensor has a high sensitivity and can thereby enhance spatial resolution by incorporating additional information received from spectral wide bands. Hence, digital imaging based on the MSFA image sensor can provide novel solutions for addressing different conditions of image acquisition, and can be employed in various applications such as military, surveillance, remote sensing, and scientific imaging applications.

Several image processing algorithms have been proposed for improving the quality of digital images. However, digital imaging based on the MSFA image sensor and Bayer CFA has certain drawbacks, such as limited resolution, color degradation, and optical aberration. Depending on the CFA and MSFA design, the sub-sampled raw data may undergo a significant loss of resolution. Demosaicking algorithms are therefore centered on resolution improvement for recovering the resolutions of the original color channels. Additionally, as spectral sensitivity differs for each wavelength, the raw data may require color balancing for reproducing the exact colors of the associated digital image. The incorporation of multiple spectral wavelengths can also generate optical aberrations that need to be rectified. To address these issues, optimal CFA and MSFA design with corresponding image processing algorithms are necessary. Furthermore, algorithms for color correction, high dynamic range imaging, multispectral fusion, sensitivity improvement, and resolution improvement are also important subjects of research in the field of digital imaging.

The objective of this Special Issue is to invite researchers to contribute papers regarding theoretical, methodological, and practical issues associated with optimal CFA and MSFA designing, color demosaicking methods, post-processing tasks for CFA and MSFA, and multispectral fusion methods.

Topics for this Special Issue include (but are not limited to) the following:

• Optimal filter array design:
• CFA design
• MSFA design
• Color demosaicking/interpolation methods:
• RGB CFAs (including Bayer CFA)
• MSFAs (RGBW, RGBNir, etc.)
• Post-processing for CFAs/MSFAs I:
• Color balancing
• Color correction
• Aberration correction, etc.
• Post-processing for CFAs / MSFAs II:
• High dynamic range imaging
• Resolution improvement
• Sensitivity improvement, etc.
• Multispectral fusion methods of multispectral channels:
• Near-infrared information
• Broadband information, etc.

Prof. Dr. Moon Gi Kang
Prof. Dr. Sukho Lee
Guest Editors

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