Image with trasparent background in a colored background inside color section

Hi,
i find a little problem with a setting in Enfold theme.
i’ve a color section with an image in background, i want put a image without the white color in background.
My site is http://www.infotografia.it and the image is in homepage, the image is a .png with a transparent section in background and i want it in the image element.
Now i see a white background for it.

i found another post where is asked the similar request, but there isn’t a issue.
The post that i saw is this:
https://kriesi.at/support/topic/need-to-change-transparency-on-image/