*3.2. Information Interaction Group*

Figure 2 shows the network architecture of the IIG, which is constructed by IIB, SSA, and residual channel attention blocks (RCABs) [48]. In IIG, the SSA is in the middle of

two IIBs and connected by two cascade RCABs in each branch, which can be formulated as follows: 

$$\left(I\_{\rm spc}^{n'}, I\_{\rm spa}^{n'}\right) = f\_{IIB,1}^{n} \left(I\_{\rm spc}^{n-1}, I\_{\rm spa}^{n-1}\right) \tag{5}$$

$$\left(I\_{sp\text{\textquotedblleft}}^{n''}I\_{spa}^{n''}\right) = f\_{SSA}^{n}\left(f\_{RCAB}\left(I\_{spa}^{'}\right), f\_{RCAB}\left(I\_{spa}^{'}\right)\right) \tag{6}$$

$$f\left(I\_{\rm spe}^{n}, I\_{\rm spu}^{n}\right) = f\_{\rm IIB,2}^{n} \left(f\_{\rm RCAB}\left(I\_{\rm spt}^{n\prime}\right), f\_{\rm RCAB}\left(I\_{\rm spu}^{n\prime\prime}\right)\right) \tag{7}$$

where *f nIIB*,<sup>1</sup>(·), *f nIIB*,<sup>2</sup>(·) represent the first and second IIB in IIG, respectively. *In speIn spa*and *In speIn spa* represent the intermediate process of IIG. *fRCAB* indicates two cascaded RCAB. The symmetrical structure of IIG is helpful to maintain the synchronization of spectralandspatialinformation.

**Figure 2.** Schematic diagram of the information interaction group, "⊕" denotes elementwise addition, and "⊗" denotes matrix multiplication.
