fix path to teaser

README.md

 ## Point Based Neural Rendering with Per-View Optimization
 Georgios Kopanas, Julien Philip, Thomas Leimkühler, George Drettakis<br>
 | [Webpage](https://repo-sam.inria.fr/fungraph/differentiable-multi-view/) | [Full Paper](http://www-sop.inria.fr/reves/Basilic/2021/KPLD21/KopanasPointBasedNeuralRenderingPerViewOptimization.pdf) | [Comparisons](https://repo-sam.inria.fr/fungraph/differentiable-multi-view/comparisons_webpage/supplementary_out/index.html) | [Video](https://www.youtube.com/watch?v=TupOewenSAk) | [Presentation](https://www.youtube.com/watch?v=u9HqKGqvJhQ&t=4755s) | <br>
-![Teaser image](./docs/teaser.png)
+![Teaser image](./docs/teaser.PNG)
 
 Abstract: *There has recently been great interest in neural rendering methods. Some approaches use 3D geometry reconstructed with
 Multi-View Stereo (MVS) but cannot recover from the errors of this process, while others directly learn a volumetric neural