Can't find image reference

Hello there,

Well this is a simple request because I’m apparently blind…

I am working on securing the site now also with SSL.
When I check the SSL-Issues I get the following:

Total number of items: 147
Number of insecure items: 1
Insecure URL: http://skywarriorthemes.com/oblivion/wp-content/uploads/2013/08/b_transparent.png
Found in: https://www.xxxxxxxxxxx.net/

This was over 10 before but I managed to locate all other images and change the link to https.

However, this image
(http://skywarriorthemes.com/oblivion/wp-content/uploads/2013/08/b_transparent.png)
seems to be hardcoded somewhere but I just can’t find it.

I tried to locate it via development tool of chrome and it seems to be somewhere in the included layerslider.

I checked all the sliders (again) and just can’t find it.

Please help!