Important: Please hold a large black piece of paper at 90 degrees to the screen so that the right eye sees the right side of the screen and the left eye sees the left side. This will ensure accurate testing.

Tap the dullest square (left or right) to select it, then swipe up to increase brightness or down to decrease brightness.

Use the Left (←) and Right (→) arrow keys if you prefer to select the brighter side, and use Up (↑) and Down (↓) arrow keys to adjust brightness.