Table 2. Contrast values (%) for seven tablets at five different nominal brightness settings.

Measurements were made with room lights off. Values are the mean of the nine calculated contrasts from values measured across the screen for black and for white squares. MC: Michelson contrast. WC: Weber contrast. All tablets met the requirements of the ICO standard (L_black/L_white ≤ 15%) and of BS 4274 (Weber contrast ≥ 90%).

nominal brightness setting	100%			75%			50%			25%			0%
	MC	Lblack / Lwhite %	WC	MC	Lblack / Lwhite %	WC	MC	Lblack / Lwhite %	WC	MC	Lblack / Lwhite %	WC	MC	Lblack / Lwhite %	WC
iPad 3	98.0	1.00	99.0	99.0	1.00	99.0	97.9	1.04	99.0	98.0	1.02	99.0	98.7	0.65	99.4
iPad 4 #1	98.0	0.98	99.0	99.0	0.98	99.0	97.9	1.00	99.0	98.0	1.04	99.0	98.7	0.60	99.4
iPad 4 #2	98.1	0.94	99.1	99.1	0.94	99.1	98.2	0.92	99.1	98.1	0.97	99.0	99.6	0.20	99.8
iPad 4 #3	98.2	0.92	99.1	99.2	0.92	99.1	98.2	0.90	99.1	98.2	0.92	99.1	100	0.00	100
iPad Air 2 #1	98.8	0.62	99.4	98.7	0.65	99.4	98.7	0.64	99.4	98.7	0.64	99.4	98.6	0.70	99.3
iPad Air 2 #2	98.7	0.67	99.3	98.7	0.66	99.3	98.7	0.64	99.4	98.7	0.63	99.4	98.6	0.70	99.3
iPad Air 2 #3	98.7	0.67	99.3	98.7	0.66	99.3	98.7	0.66	99.3	98.7	0.68	99.3	98.5	0.74	99.3