iPad mini 3 and iPad Air 2 Absolute Color Accuracy Plots    
    Reference Colors for the Standard sRGB/Rec.709 Gamut  
Figures 2a 2b 2c

Reference sRGB / Rec.709 Colors
Virtually all current consumer content is based on the sRGB/Rec.709 Color Gamut Standard. Figure 2a below shows 21 Reference Colors for the Standard sRGB / Rec.709 Color Gamut as White, Gray, and Black circles, The 10 Black circles are the 100 percent fully saturated colors on the periphery of the Gamut triangle. The 10 Gray circles are the 50 percent saturated colors that are exactly midway between the White Point and the 100 percent saturated colors on the periphery. The White circle is the White Point with zero percent color saturation.

Uniform Color Diagrams
All color measurements are plotted on 1976 CIE Uniform Color Diagrams.
Note that the older 1931 CIE Diagrams that are published by many reviewers are highly non-uniform and are meaningless for Color Accuracy.

Absolute Color Accuracy Plots
Figures 2b 2c below show the measured on-screen colors of the sRGB/Rec.709 Reference Colors for the iPad Air 2 and iPad mini 3.

Reference Colors
The Reference Colors in Figures 2b-2c are all shown as Black circles and the measured Colors for each of the iPads are shown as Red circles. Color Errors smaller than the appropriate JNCD are not visually noticeable. The 1 JNCD and 3 JNCD Errors are discussed next and are shown in the Figures below.

Just Noticeable Color Difference JNCD
The on-screen colors produced by any display can be measured using a Spectroradiometer together with our DisplayMate Test Patterns. The accuracy of the colors can then be calculated using the 1976 CIE Uniform Chromaticity color space and compared to the eye's sensitivity to color. We present the color accuracy and errors here in terms of MPCD Minimum Perceptible Color Difference or JNCD Just Noticeable Color Difference, where 1 MPCD = 1 JNCD = Δ(u'v') = 0.0040 on the CIE 1976 Uniform Chromaticity Scale.

Color differences less than 1 JNCD are visually indistinguishable, while values greater than 1 JNCD are visually noticeable when the two colors are touching on-screen. When the colors are not touching and are further apart, the visual threshold for Just Noticing a Color Difference is higher. Here we will use 3 JNCD for the threshold of a visually noticeable display color difference. The 1 JNCD and 3 JNCD sizes are shown in the Figures below. Any Display Color Error less than 3 JNCD on a display is not visually noticeable and appears perfectly accurate to the eye.

Figure 2a.   sRGB / Rec.709 Reference Colors
Note that Complementary Colors lie directly across from one another through the White Point.
The 50% Saturated Colors are midway between White and the 100% Saturated Colors.
Reference Colors for sRGB / Rec.709

Figure 2b.   iPad Air 2 Absolute Color Accuracy Plots
Absolute Color Accuracy for the displays

Figure 2c.   iPad mini 3 Absolute Color Accuracy Plots
Absolute Color Accuracy for the displays

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iPad mini 3 and iPad Air 2 Display Technology Shoot-Out Article
Mobile Display Shoot-Out Article Series Overview and Home Page