I want to dim the script below "0" on my iMac. Here is my current script, but this stick to OSX settings.

    tell application "System Preferences"
        reveal anchor "displaysDisplayTab" of pane id "com.apple.preference.displays"
        delay 8
        tell application "System Events"
            set value of slider 1 of group 1 of tab group 1 of window 1 of process "System Preferences" to 0
            delay 5
        end tell
    end tell
on error
    display notification "Dim screem down failed"
end try

I found this app "Shady" which is going even below. They have a link for the Open source on they Web site but 404.

Any idea how to implement that with AppleScript?

  • A setting of less then zero will have no affect! The Shady app does not utilize that setting anyway. It essentially sets a translucent window as the top-most and always-on-top and adjusts its opacity and why it can go darker than what a zero Brightness setting under Displays in System Preferences does. BTW Here is the link for the source code. Commented Apr 13, 2016 at 15:31

1 Answer 1


As was noted in the comments, brightness cannot go below a setting of 0. If you use the brightness keys on your mac, you'll note that if you keep going, you hit screen off, which entirely turns off the screen backlight. From experience, I would assume this is zero. Below zero would mean your screen is actively attracting light from it's surroundings. You can adjust some settings by 1/4th notches by holding the option key and pressing any of the adjustment buttons, but that's as close as you'll get. What shady is doing is merely darkening all of the colors on your screen, which does decrease brightness because of how well made lcds work, but I'm not sure if that's exactly what you're after, as that can definitely affect how colors look otherwise. EDIT: If 1/4 brightness increments are not enough, shady and those small increments should stack in effect, but some older macs can't dim their brightness in 1/4th increments after you get down to one notch.

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