Perspective Chapter: Mix-Unmix Pan-Sharpener – Novel Pan-Sharpening Method Based on Mixing Constituent Multispectral Bands and Unmixing Panchromatic Band

A panchromatic band (Pan-band) spectrally covers a number of the other bands (multispectral-bands, MS). The Pan-band is of higher spatial resolution than the MS. The respective advantages of the two are combined through pan-sharpening with the resultant image adopting the higher spatial resolution of the Pan-band and the colour information of the MS. Various techniques have evolved but most of them cannot pan-sharpen more than three MS, and none of them can pan-sharpen more than three MS at a go, nor pan-sharpen a multispectral image not geographically covered by the Pan-band. This novel concept overcomes the first problem. The sequel to this chapter will address the second problem through reverse pan-sharpening. The concept argues that for a given pixel in the Pan-band, the strata of digital numbers (DNs) in the MS combine to give rise to a panchromatic-DN. The concept estimates respective coefficients of strata of DNs in the encompassed bands corresponding to pure blocks of pixels in the Pan-band. On the basis of the coefficients, encompassed bands’ DN contributions to the panchromatic-DN are computed from the Pan-band DN. The resultant DN contributions are regressed on the MS-DNs and one of the encompassed MS pan-sharpened on the basis of its model. The other multi-spectral bands are pan-sharpened through it.