Hello dunxmax,

the Fastslider module works with transparent PNG images - however, PHP's gd library can only use one color for transparency (i.e. background transparency).
This means that if you use e.g. shadows which fade out in your iamge, the result might not be what you want.

Generally speaking, you'll get the best results with JPG images - please see our demo:

demo.extro.media/responsive-joomla-exten...esponsive-fastslider

You can also take a look at the backend:

U/PW: demo