Intensity mixture and band-adaptive detail fusion for pansharpening

Pansharpening aims to sharpen a low-resolution multispectral (MS) image through a high-resolution single-channel panchromatic (PAN) image to obtain a high-resolution multi-spectral (HRMS) image. However, low correlation between the PAN and MS images, as well as the inaccurate detail injection for each band of MS image are the key problems causing spectral and spatial distortions in pansharpening. To address these issues, a new pansharpening method based on the intensity mixture and band-adaptive detail fusion is proposed. To obtain a mixed-intensity image (T) that has a high correlation with the MS image and maintain the gradient information of the PAN image, the intensity mixture model is constructed by establishing the intensity and gradient constraints between T and the source images. As it is hard to obtain a proper degradation filter in the model, a filter estimation algorithm is designed by the distribution alignment. To inject the details that match the point spread function of the sensor, a band-adaptive detail fusion algorithm is presented to fuse the details extracted from T with those from the MS image for each band. Furthermore, as there are far fewer details in the MS image than in T, a detail enhancement algorithm is proposed to enhance the details proportionally. The final HRMS image is obtained by injecting the fused details into the upsampled MS image. Extensive experiments show that the proposed method can efficiently achieve the best results in fusion quality compared to state-of-the-art methods. The code is availabe at https://github.com/yotick/IMBD.