Use a photo editor and apply the invert or negative filter
On Windows, press Ctrl + Alt + I in supported apps
On Mac, use the app’s invert colors option or press Command + Option + I in supported apps
On iPhone, go to Settings, Accessibility, Display & Text Size, then turn on Smart Invert or Classic Invert
On Android, go to Settings, Accessibility, then enable Color inversion
In web design, use CSS filter: invert(1)
In Photoshop, use Image, Adjustments, Invert
In GIMP, use Colors, Invert
In many apps, search for Negative, Invert, or Color inversion in the settings or edit menu