update readme

Author: wokaikaixinxin

README.md

@@ -9,7 +9,7 @@
 [IEEE TGRS Link](https://ieeexplore.ieee.org/document/11424629)
 
 <div align="center">
-  <img src="./teaser.jpg"  width="800"/>
+  <img src="./teaser.png"  width="800"/>
 </div>
 
 ## Abstract