This is a common question from our users. The answer is because measurement of any type of visual skill related to Contrast such as Contrast Sensitivity Function or Low Contrast Visual Acuity requires from a previous characterization of the display in order to correct the gamma function. In...

In the iPad you can select the percentage of brightness of the screen, however you need to know what is the background luminance for that brightness. The relationship between the percentage of brightness and the luminance can vary between models and has been reported by Livingstone et...