You can change the styling of an image that is uploaded to a Hello Bar Site Element. 

If you want to change the default image from a Hello Bar Template, refer to this article to learn how to do this. 

First, navigate to the Design Tab and open the Image widget.

There are 3 settings you can change with an image.

Change the Opacity of the image.

Add an Overlay on top of the image and set the color of the overlay.

Lastly, in order to see the Overlay you can change the Opacity of the Overlay.

If you do not want to any settings to alter your image, set the Opacity setting to 100% and set the Overlay Opacity setting to 0%.