How to Get an iPad out of a Negative Color Effectby Ryan Menezes
Apple's White on Black feature inverts an iPad's colors, changing the text to white and the background to black. When you read documents in low-light conditions, such as on a dark airplane during a business trip, the White on Black feature reduces the strain on your eyes and causes the text to appear more legible. However, the feature inverts all colors, not just white and black, applying an unwanted negative effect to images and video. You can disable the White on Black feature through the iPad's accessibility features.
Open "Settings" from the iPad's home screen.
Tap "General" in the Settings sidebar.
Tap the button beside "White on Black." Slide it from "On" to "Off" to disable the feature.