Increase Background Image Brightness Slider Grayed Out

[Yodlei]

S5 Pro & all LEDs. Tried searching & found nothing but pixel info. I've had to change colors of some props in my preview in order to see them better on the screen. Blue especially bad. Thought maybe changing the background might help but see the slider is grayed out. Didn't see any other option to change. Am I missing something and/or would lightening the background not help anyway? Thanks!

[PhilMassey]

The brightness slider in Preview is to change the brightness of the your background image, if you have applied one.

[Yodlei]

2 hours ago, PhilMassey said:

The brightness slider in Preview is to change the brightness of the your background image, if you have applied one.

Awww crap! Thanks & sorry so late!!

[k6ccc]

And if you do not have a background image, the slider is grayed out.