QNR Optimization based Pansharpening

Quality Without Reference (QNR) index can be used to globally assess the quality of pansharpened images without the need of a reference high resolution multispectral (MS) image. The QNR index relies on local calculation of the Q4 index. Exploiting the local Q4 calculation property of the QNR index, we propose an injection model for pansharpening. The injection model determines the weight of extracted panchromatic (Pan) details that are to be added into the upscaled MS images to obtain the best QNR index. The QNR index calculates spectral distortion of the fused images with respect to the low resolution MS images and spatial distortion of the fused images with respect to the high resolution Pan image. Hence, the QNR optimized fused image is spectrally consistent with the low resolution MS image and spatially consistent with the high resolution Pan image.