Header Image Overlay Opacity

Is it possible to control the header image overlay opacity? I would like to have the image only.

http://nas.danielbierstedt.de/bogensport-leverkusen/

Hello,

You can apply custom css code below with for ex. this plugin https://wordpress.org/plugins/simple-custom-css/

.header-image::after {
    background-color: rgba(0,0,0,0.6);
}

and change last value which is for opacity (0.0 will show image without overlay).

You can also find folowing link helpful in order to generate RGBA value from hex value http://hex2rgba.devoth.com/

Works, thank you.