Optimising your PC’s screen colours cuts eyestrain, reduces headaches, and helps you sleep at nights. It can be surprisingly easy, too – set up a program like SunsetScreen and it works largely automatically.

There may still be times when your display is too light, or maybe too dark, though, and that’s where NegativeScreen comes in. It’s a tiny freeware app for Windows 7 and later which can invert your screen colours on demand.

Unzip the download (an impressively small 71KB), run NegativeScreen, and you’re able to toggle the “negative” effect by pressing Win+Alt+N. The entire screen – the desktop, videos, games, anything accessing the screen through Windows – updates right away.

Inverted screens can look weird, but NegativeScreen offers various inversion modes to help

This can make colours look a little weird, but NegativeScreen offers various other inversion modes which might be able to help. Typically they’ll still try to reduce glare by inverting black/ white shades, but keep colours more or less the same, although others don’t actually invert colours at all (there are red and greyscale modes).

None of these effects will work in every situation, but that’s not a problem. If NegativeScreen’s inversion gets in the way at any point, hitting the hotkey again toggles it off and returns you to normal.

This is all useful enough, but what we didn’t expect was NegativeScreen’s extreme configurability. If you’d like to change one of the hotkeys, edit an inversion mode, maybe create a new effect of your own – greenscale sounds good to us – then all you have to do is edit the negativescreen.conf file. It’s all relatively easy, but if you do need any help then comments in the file tell you more.