This image size from the theme demo works great: http://themes.themolitor.com/wpbm/files/2011/05/Shake_it_Softly.jpg

Try scaling your images down a bit to be closer to this size. Your images are so large now they are too large for most screen resolutions. Doing some prep work on your images prior to uploading can really enhance your users experience and effect the distortion issue you're encountering.

Hopefully that makes sense.

Thanks,
Justin

Thanks for your answer Justin. The thing is that the featured image on the portfolio view actually works fine. The problem come in the post itself, instead of cropping them they are distorted.

Your vertical images are not the best shape/size for a thumbnail to be produced. I would suggest creating more of a square for your featured image.

Hi!

All my vertical images appear as distorted thumbnails. You can check an example here: http://lunavandoorne.es/?p=738

Any idea how to fix that?
Thanks!