Image hover text dimming

So I have some clickable links on my images and I added a hover css so that it changes the brightness  of the image to 50% when hovered.  But in turn it is also dimming the text that is laid over it.  I have these images in a poster style.  What code and I input to keep my brightness dimming on the image but exclude the text and keep that a full brightness.  

Here is my code for that.

.image-block .image-linked:hover { filter: brightness(67%);}