An optimal weighted averaging fusion strategy for remotely sensed images

Image fusion plays a vital role in providing better visualization of remotely sensed image data. Most earth observation satellites have sensors that provide both high spatial resolution panchromatic (PAN) images and low resolution multispectral (MS) images. In this paper, we propose a new fusion algorithm that optimally combines spectral information from MS image and spatial information from the PAN image of the same scene to create a single comprehensive fused image. As the performance of the fusion scheme relies on the choice of fusion rule, the proposed algorithm is based on a weighted averaging fusion rule that uses optimal weights obtained from brain storm optimization (BSO) algorithm for the fusion of high frequency and low frequency coefficients obtained by applying Curvelet transform to the source images. The objective function in BSO is formulated with twin objectives of maximizing the entropy and minimizing the root mean square error. The fusion results are compared with the existing fusion techniques, such as Brovey, principal component analysis, discrete wavelet transform, non sub-sampled contourlet transform, and intensity hue saturation. From the experimental results and analysis, the proposed fusion algorithm gives a better fusion performance in terms of subjective and objective measures than the traditional algorithms. As a benefit, the proposed fusion scheme preserves spectral information of the MS image with increased spatial resolution and edge information.