Remove Grey from Templae Header Background Image

How would I remove the grey overlay on the Template Header Background Image? I removed the grey overlay for the Homepage Slider by using the code below, but wasn't sure how to remove the grey from the Header Background. Thanks.

.nivo-caption {
background: none;
}

 

I think I found the solution. I added the following code in CSS and it removed the Grey overlay in both the Homepage Slider and the Template Header Background Image.
.nivo-caption, .top-bg-mask{
background:none;
}