Suggestion: auto brightness & contrast for background images

I´m using background images, or back drops, a lot. But mostly i have to employ some graphics application to brighten the images & lower the contrast, in order to make

it bright enough to avoid interfering with the lister´s font. So i could imagine some additional parameters to the PREFS ADDBACKGROUND command, like

PREFS ADDBACKGROUND,brightness=3, to "bleach" the image to the desired extent. In my example the value "3" would represent the strongest amount of brightening.