*Article* **PWNet: An Adaptive Weight Network for the Fusion of Panchromatic and Multispectral Images**

#### **Junmin Liu \*, Yunqiao Feng, Changsheng Zhou and Chunxia Zhang**

School of Mathematics and Statistics, Xi'an Jiaotong University, Xi'an 710049, China;

fyq9719@stu.xjtu.edu.cn (Y.F.); zhouchangsheng3@stu.xjtu.edu.cn (C.Z.); cxzhang@mail.xjtu.edu.cn (C.Z.)

**\*** Correspondence: junminliu@mail.xjtu.edu.cn; Tel.: +86-029-82663155

Received: 31 July 2020; Accepted: 24 August 2020; Published: 29 August 2020

**Abstract:** Pansharpening is a typical image fusion problem, which aims to produce a *high resolution multispectral* (HRMS) image by integrating a high spatial resolution *panchromatic* (PAN) image with a low spatial resolution *multispectral* (MS) image. Prior arts have used either *component substitution* (CS)-based methods or *multiresolution analysis* (MRA)-based methods for this propose. Although they are simple and easy to implement, they usually suffer from spatial or spectral distortions and could not fully exploit the spatial and/or spectral information existed in PAN and MS images. By considering their complementary performances and with the goal of combining their advantages, we propose a *pansharpening weight network* (PWNet) to adaptively average the fusion results obtained by different methods. The proposed PWNet works by learning adaptive weight maps for different CS-based and MRA-based methods through an end-to-end trainable *neural network* (NN). As a result, the proposed PWN inherits the data adaptability or flexibility of NN, while maintaining the advantages of traditional methods. Extensive experiments on data sets acquired by three different kinds of satellites demonstrate the superiority of the proposed PWNet and its competitiveness with the state-of-the-art methods.

**Keywords:** pansharpening; component substitution; multiresolution analysis; neural networks; adaptive weight
