Update README.md

README.md

@@ -16,7 +16,7 @@ Paper abstract:
 - **Preprint:** [arXiv:2505.13755](https://arxiv.org/abs/2505.13755)
 - **Repository:** https://github.com/abao1999/panda
 
-![skew system parameter perturbations](skew_system_param_perts.pdf)
+![skew system parameter perturbations](skew_system_param_perts.png)
 
 ## Citation